CLARIFICATION: I got a lot of comments on my previous 'Was Early Earth More Extreme' video saying that the ~2.4 billion yr ago snowball Earth does not have as robust evidence as the later ~700-600 snowball earth events. I should've made that more clear in that and this video, so I am writing this comment to clarify that Earth history is really well studied and we have been able to reconstruct many events and trends through Earth history with a multitude of corroborating lines of evidence, but some events have less evidence backing them up than others. This isn't because these events are less studied, it is most often because we have a patchy rock record and some periods in Earth's history are just not preserved as well as others. So just please understand that everything I discuss regarding events in Earth's past are hypotheses and sometimes I forget to use words like potentially or possibly. But also be aware that many ancient events are very well backed up with many lines of geochemical and paleobiological evidence, and people (including myself) work everyday to refine our methods of reconstructing Earth's past. :) These comments actually inspired me to work on a future video about 'how we reconstruct Earth's history', the specific geochemical methods we use to figure out what happened in Earth's past. Let me know if that's something you'd like to see! ;)
Yes! That sounds like an excellent topic for a video, or probably a series of videos. Oxygen isotope ratios vs. periods of glaciation, trace metals, iron oxidation - plus the environments where these changes in geochemistry occurred, deep vs. shallow marine. It’s a lot of puzzle pieces to put together! Something like that sounds like a perfect idea for pulling together the knowledge you’ve shared in a lot of your previous videos. Go for it!
Yes, big YES on a video on geochemical methods. Yours are the best vids on geology on YT IYAM, Rachel, & some of the best science vids period. Thank you again for your great work.
History is simply the current best explanation by the evidence in hand. No one should get their feathers ruffled over it - especially exact dates. Oh, and I might've missed this in your video, but the strength of the magnetosphere determines how much radiation enters the atmosphere. So does CO2 determine global temps or does the CO2 level follow temperature changes? We're at 415ppm of CO2 now (or about .04% of atmosphere) & below 150ppm everything dies. Why is there a war on plant food?
As a kid I have never been Interested in geoscience or geology. This has changed so much in the last year because of interesting results from geophysics (early earth formation, moon creation, climate change, stratospheric cooling physics) and above all because of your channel. I really owe you a bigger picture of the world. I wonder if the statement that solar and planetary physical influences on the climate are less “real” should mean “less tangible in rock history” - given the formidable improvements in computer simulations, there must be evidence on evolution or changes in earth dynamics. Capo for your excellent science communication and your intelligent deep dives. Don’t change anything! (please no music at the end).
Just came across your channel yesterday and as someone who has enjoyed prehistory for most of my life it was an instant subscribe. Thank you for creating these informative and educational videos! 👏✨
A few pedantic suggestions: 1) in the graphic (first one at 3:00) change "excentricity" , which is a term that has popped up in some social commentary, with the proper spelling); 2) regarding the "tilt" - the poles receive less solar radiation _at the annual maximum_ (summer solstice) when there is less tilt. Thus less summer melt.
The Milankovitch model suggests that the dominant factor in variations should be the 41,000 tilt cycle, as tilt has the greatest effect on seasonal intensity. Oxygen isotopes have shown that, for the last ~800 kyrs, the 100 kyr cycle has dominated though orbital eccentricity should be the weakest factor. I bring this up because I remember seeing a talk ~30 years ago by a Berkeley physicist (whose name escapes me but he had worked with Luis and Walter Alvarez on the impact hypothesis) who suggested that there is another 100,000 year orbital cycle: this cycle occurs when the Earth's orbital plane periodically lines up with the solar equator, during which there is a marked increase in the amount of dust in our orbital lane that reduces overall solar intensity. He suggested that this might explain the dominance of the 100 kyr cycle. I've not heard this since that talk and I'm curious if you or your community of subscribers ever recall hearing this mentioned...
The change from 41K yr ice cycles to 100K cycles beginning ~1M yrs ago, the 100K yr problem, even has its own Wikipedia page. A number of hypotheses have been proposed.
The Sturtian and Marinoan glaciations are named after 2 localities close to Adelaide, South Australia. The Sturt Tillite can be found in the Sturt Gorge Recreation Park, but is really widespread across the state. The Antarctic explorer, Douglas Mawson was involved in research to date these various glaciations. It seems he had a life-long connection to all things glacial!
Hi there Geo Girl. Another excellent presentation :) I always learn something new. I'm glad you mentioned at the outset that Earth's climate has warmed and cooled throughout it's long history. As I believe you've said before, climate and such is a very complicated process. The approach needs to be opened-minded and not forced into a politically motivated box. About the Milanković Cycles, would you happen to know if they began to affect the planet beginning at the Late Eocene Epoch when Earth began to cool, or was it not until the beginning of the Pleistocene? To me this seems to be a rather complicated time in Earth's history. Besides the advent of cooling, there was also the Eocene - Oligocene Extinction Event, and the Chesapeake Bay Bolide Impact Event. I am of the opinion that these are all somehow connected, but this is not one of my areas of knowledge. gfs
It wasn't until the Pleistocene that they really started to cause major interglacial cycles. It is complicated, like you said there are so many factors at play and it is also difficult to interpret small trends (like interglacials) within larger, longer more gradual cooling or warming trends. I actually have a video on the Eocene-Oligocene Extinciton (th-cam.com/video/Eq4Dx-JPBuE/w-d-xo.html), and I think I mention that impact in that video as well, but I can't remember that might be in a different video haha ;) I also agree about the complexity of climate change throughout Earth's history and on modern Earth, it baffles me that people try to make it political in any way...
@@GEOGIRL I just don't think it has anything to do with CO2. The data just doesn't present any evidence that climate changes is caused by CO2. Well, the data I could get, at least. It's hard to get actual data from the climateers anyway.
We can actually reconstruct past orbital conditions. The nice thing about Newtonian mechanics is that it’s really easy (relatively) to predict how planetary bodies will move in the future given enough data points. Knowing this knowledge, we can actually turn back the clock and give our best guess as to what the orbital conditions were. However, it’s hard to account for random events like giant impacts and such.
"We can actually reconstruct past orbital conditions. " - but the small errors at the initial conditions increase the uncertainty significantly in the out years past a couple of million.
Something to consider is the flight of the Sun through the regions of space around the galaxy. We fly around, and just outside one arm of the galaxy as the galaxy turns and we have been around that arm and rotated with the galaxy several times since Earth formed. Doing so, we have passed by many other astronomical bodies, great clouds of gas, intense magnetic and gravitational fields and turbulence from collisions with other, small galaxies. Time is very deep and complex things happen that are hard to trace.
@@fredwood1490 The spiral arms don't rotate as solid objects with the sun at a fixed distance from them. Spiral structure is more like a shock wave in the interstellar medium, delineated by star-forming regions containing young stars, some of which are very bright and short-lived, dying in supernova explosions. The sun's orbit around the galactic center takes ~225 million years and should have carried the solar system through star-forming regions many times in Earth history. These passages through star-forming regions could occasionally bring the Earth close enough to supernovas to affect conditions on the Earth, and possibly Earth life. However, in most of Earth history life was single-celled and the rock record is sparse, so it is very hard to tell when there were extinctions until the Phanerozoic. During the Phanerozoic, the sun has completed about 2 and 1/2 galactic orbits, and should have been near star-forming regions several times, but all the major and most minor mass extinctions in the Phanerozoic seem related to climate change.
@@ellenmcgowen Exactly, though I hadn't thought about the spiral arms being shock waves, it makes sense. My point being that there is a lot more to Earth's history than the bit we are living through right now. How many more "Snow Ball Earths" are lost in the rock records? How many gamma ray bursts? Life is said to have developed within the first billion years after our forming, but multi-cellular life not until the last billion years. Given the rate of change and development we can read in the fossil record, what held up that development?
Wonderful presentations. Thank you. It was your words that invited us to consider ice to be a rock -- which lead me to a few seminars found in the playlists of NASA Goddard Institute for Space Studies. Nice to see how ice moves... it is rock. (You are a Rock Star! )
The solar system travels around the galaxy passing through areas with more or less dust and this also could affect climate by blocking sunlight? Don't know but recall seeing this suggested a couple of decades ago.
2:50 The diagram of Earth's elliptical orbit shows the Sun at the center of the ellipse. The Sun would actually be at one of the "foci" of the ellipse. This is important for thermal changes, because the Earth spends less time in the part of its orbit near the Sun, and more time farther from the Sun. Earth's orbital speed gets slower as it gets farther from the Sun. In very eccentric elliptical orbits such as some comets, they whiz past the Sun in a very short time, then slow their travel far from the Sun to spend decades to millions of years in the cold outer solar system. 3:44 For the orbital diagram in the video, the mouse cursor is used to show that the Earth is closest to the Sun at the shortest distance across the ellipse (along the minor axis of the ellipse). But the Earth is actually closest to the Sun at one side of the longest distance across the ellipse (one side along the major axis of the ellipse). This is because the Sun is not at the center of the ellipse, but at one of the foci of the ellipse.
Also the reason why the "figure 8" Analemma is lopsided from Summer to Winter. It would be more symmetrical if the orbit was sun-centered. In a perfectly circular, sun-centered orbit, the analemma would "collapse" into a north-south line.
Wow! Someone who presents the fact without having an axe to grind. Another factor in the effectiveness of the Milankovitch Cycles has to do with how much land there is between 30 degrees north and 70deg. north as opposed to how much open ocean there is in the same band of the southern hemisphere. This also affects northern hemisphere glaciation vs. southern. Land heats and cools faster than sea water.
Thanks for the feedback! I have actually changed it since this video, so watch a recent video and let me know what you think. I think it is better now! But I don't have the audio ear, so having the feedback is helpful :)
FYI, I think Brian Cox mentioned it, we are able to recreate earth's orbit, and other planets orbit up until, allegedly jupiter was roaming chaotically around the sun. So we should be able to see exactly earth's position 3-4 billion years ago, but we can't really know earths position prior to that.
It would be nice if you made a similar video except that you try to extrapolate into the future. Based on what we know about the past, can we predict how changes in tectonics and all that jazz will affect the climate in the future? Like, when will the next major ice age or snowball earth happen? Or WILL it ever happen given all the carbon we're putting into the atmosphere and the fact that the sun is getting hotter? I remember hearing on another TH-cam video that with the sun heating up, probably all life on earth will end within the next one billion years. It might've even been shorter than that.
In about 1 billion years it can be expected that without any intervention all higher life will have ceased to exist on Earth. Though the demise will start way earlier. The luminosity of the sun is increasing and in about 500 million years it can be expected that the greenhouse effect gets unstable. Higher temperatures will increase the amount of water vapor in the atmosphere which in turn will lead to higher temperatures as water vapor is also a greenhouse gas. Though the real problem for life will not be the temperature increase but the increased weathering due to the increasing amount of (warm) rain. As a result the CO2 levels in the atmosphere will drop and will reach in about 900 million years the critical level where plants can no longer survive. Due to this life (or at least all higher life) will most probably be extinct long before Earth reaches the point where it enters a runaway greenhouse effect much like Venus (will happen in about 2 billion years).
Atmospheric water, in higher amounts from hot temperature, transports latent heat high enough into the atmosphere that there is little CO2 to stop that heat from then radiating into outer space. At current conditions, the tug of war between on the one hand latent heat transport by atmospheric water and the Stefan-Boltzmann equation and on the other hand the greenhouse effect of atmospheric water is about a tie, explaining why in the last million years or so tiny changes in sunlight falling on Earth have made big differences in temperature. In much warmer conditions, the extra heat carried aloft and then released by water turning into liquid or solid at high altitudes more than outpaces the extra greenhouse effect, meaning in practice that there is a cap on how hot Earth can get with a given solar constant, unless Earth's oceans dry up of course. Earth did not turn into another Venus during the end Permian and go into a runaway greenhouse effect. Part of what was going on is that water is not a "well mixed" atmospheric component on modern Earth and as such, in practice the exponent for determining infrared optical thickness from water is lower than that of CO2. In addition, unlike with CO2, the exponent for water appears to decline with temperature, rather than staying close to constant over a broad range of temperatures and pressures. If the exponent for atmospheric water increased with temperature on Earth, or stayed constant with increasing temperature on Earth, Earth would have indeed gone into a runaway greenhouse state. What can be referred to as mathematical "plate count" is about 3/4 of the infrared optical thickness, where each mathematical plate represents half of all infrared radiation escaping outward, and half being redirected inward. Fractional plates are possible, and are actually typical. The greenhouse temperature multiplier is (1 + PlateCount) ^ 0.25, a mathematical expression in which the 0.25 exponent comes from the inverted form of the Stefan-Boltzmann equation, an equation that you can look up on the Internet if you are interested. The usual non-inverted form has the number 4 as the exponent. The mathematical reciprocal of 4 is 0.25, explaining why 0.25 is the exponent in the inverted form of the Stefan-Boltzmann equation.
@@wendydelisse9778 It sounds as though you have the ingredients of a 1-d model that could be run with increasing solar constant from stellar evolution of the sun to predict the time at which the oceans boil off.
The freezing point is more important than the boiling point. Mars still has some water away from the poles of Mars because that water is cold enough to normally still be in frozen form, and therefore is somewhat protected by being a part of the geology of Mars. Earth does not have that protection of water being in frozen form away from the polar regions, and yet Earth still has an ocean cover fraction of about 2/3. Earth has a different protection insteas for its water, protection that is ultimately due to a ratio of orbital velocity about the Sun to escape velocity from Earth that is less than 3 to 1. For retaining atmospheric dinitrogen in a no ammonia atmosphere within the orbit of Uranus, less than a 4 to 1 ratio is good enough for a planet-sized object, as is seen with Titan (3.66 to 1) and Venus (3.38 to 1) and Earth (2.66 to 1). (For a moon, use the orbital velocity about the planet instead if greater than the orbital velocity of that moon and its planet around the Sun). To begin the explanation of the special protection that Earth gets for retaining liquid water away from Earth's poles, Moon astronauts orbiting the Moon some 50 years ago noticed a pre-sunrise diffuse glow, with their claims backed up by camera evidence. The molecular cause of that pre-sunrise diffuse glow is why Earth still has a substantial liquid ocean. That glow comes from the scattering effect of a thin atmospheric veil of neutral monatomic hydrogen (chemical formula H1 or more simply H) that extends outward from Earth for about twice the radius of the Moon's orbit. Earth's gravity in relation to Earth's orbital velocity is strong enough to maintain a still conditionally visible veil of neutral monatomic hydrogen in spite of the effects of micrometeorites and solar wind, and is part of the explanation for why it took Earth billions of years to lose enough hydrogen atoms for dioxygen (O2) to be present in greater than trace amounts in Earth's atmosphere. Hydrogen atoms were escaping to beyond the mesopause, but a fairly large number of hydrogen atoms were also coming back in from that thick enough and broad enough veil of neutral monatomic hydrogen. As dioxygen (O2) and ozone (O3) partial pressure rose, the escape to capture ratio of hydrogen atoms by Earth attained approximate chemical equilibrium of 1 to 1 when dioxygen partial pressure at sea level got to about 25,000 pascals. Oxygen binds very tightly with hydrogen, and so the presence of greater than trace amounts of free oxygen on Earth, in combination with Earth's thick enough and vast enough veil of monatomic hydrogen, allows Earth's oceans to retain their hydrogen atoms. Higher temperature from a higher solar constant will mean that more dioxygen will form as some hydrogen atoms gradually escape from Earth as a result of higher temperature assisting the dissociation of water molecules, thus restoring close enough to a new equilibrium that would still allow Earth to retain most of its ocean water. Ultimately, that higher future partial pressure of dioxygen will possibly become more of a threat to life on Earth than rising temperature. Short version: Earth's oceans have good enough protection from losing their hydrogen atoms, due to the presence of a thick enough and vast enough veil of monatomic hydrogen that extends from Earth to beyond the orbit of the Moon. For Earth, the big long term threats to life forms are instead rising temperature and the resulting greater partial pressure of free oxygen, rather than the loss of enough hydrogen atoms to cause the oceans to disappear, a process that happened on Venus.
Not wearing my glasses, lol, I did a double take on the orbital precession diagram at ~10:30 to see if it really said "to vegas". Wouldn't that be something. Anyway, thanks for the video!
It is fascinating that the nanoplankton 016/018 ratios (from sediment coring during the mid-late 20th century) independently support the Milankovitch model (postulated in the early 20th). I like to refer to this as science at its most elegant.
Sulfur and the ash. By the way, I have difficulty communicating because I had a stroke in Broca’s area, the part of the brain that controls speech. 2/8/2021 but I lived again. (My wife helped me compose this.)
12:35 Do you want to say that the formation of coal beds ("seams") form the carboniferous period does not line up with Milankovic cycles (theses cycles might have changed somewhat over the last 300 million years, but the basic principles should apply throuout the times). I've been under the impression that fluctuations in carbon burial, hydrocarbon depositions, seawater levels in past ice ages - apart from the global glaciation "snowball earth" events - were also an expression of the Milankovic cycles back then and that it is acutally mostly recurrent glaciation events that drive the formation of coal, oil and gas deposits.
Earth really just seems to go through a hard time everytime it plays matchmaker and these super continents just end up breaking up. I totally get that!
@meesalikeu it seems like earth had to experience a couple tough relationships with its continents coming together, but through all time positive lessons were learned, and you can see it in the life that thrived in those times
10:50 Sorry, I can't follow you on this line of reasoning - the connection of North and South America broke the "circumequatorial" (I am making this word up) ocean stream the stream of water from east to west around the equator and redirected that warm water as "gulf stream" to the North Pole. How would this lead to cooling of the Arctic Ocean?
Oceanography is my weak spot but my understanding is a current formed around NorthAm; not dissimilar from circumpolar current around Antarctica... but warm. The isthmus stopped it
Thanks! Perhaps I can say regarding the astronomical causes that modern interpretation would be to consider how various cosmic variables could influence the Earth as it undergoes its processes, however I believe that the critical benefit of incorporating astronomical influences is from a Hermetic sense of, "as above, so below;" where the ways in which the Earth functions are closely compared to other known bodies in the cosmos. Pattern inference is crucial in scientific endeavors, and if we are stuck then it means we have exhausted the patterns that we have noticed that are most able to transform collective awareness. One such pattern that looking to the cosmos can help reveal is that there is a spectrum of stable systems that form--stars, planets, atoms, black holes--and so we can consider the pattern itself and ask "is there any reason this pattern would end?" which, from a purely philosophical standpoint based in mathematics, there is no reason. Scientific consensus states otherwise, suggesting there to be an elementary particle of which all else is composed--once the atom, now subatomic particles. However, the existence of the inferred subtler and more massive still systems can help explain how observations such as magnetic fields and gravity emerge from a simple pattern, essentially of an infinite nature. As subtler systems are more abundant (there are more atoms in the universe than there are planets, for instance), mechanisms can be envisaged. Where gravity can be seen to be manifest from the motions of particles that would make photons look like black holes in comparison, that flow in all directions towards any given object and then when another system is near it blocks a portion of the flow of these particles and induces a relative low pressure on one side and causes attraction between the systems according to distance of separation and mass. And where particles can pass through other particles like neutrinos passing through the Earth, but be locked in a Figure-8 orbit in large abundance and cause fields (magnetic fields). This though implies an infinite range of particles and so it is either infinitely complex, or they all behave the same but seen from a different angle of perception. There is no debate amongst humanity that we are all composed of the same constituents (atoms). Every other system in the spectrum of particles we see uses the atoms we are composed of to view it. But that does not mean all life is composed of what we call atoms. If there is an infinite spectrum of particles then it would be only reasonable that an observer could be composed of any of them--there would be no reason that the "atoms" of which we are composed are more "atom-like" than anything else in an infinite spectrum. I say all this to say that, Earth is within this spectrum as well. It's mechanics are not separate and distinct from stars, but rather only seen from a different angles. For instance, the Earth has sunspots known as E.L.V.E.S. and solar flares that project through the E.L.V.E.S. known as sprites. It has a photosphere of the air glow of the ionosphere. It radiates light--in the infrared spectrum. It has the inner and outer Van Allen belts like the asteroid and Kuiper belts. It is a star. And stars can supernova, which is really a process of rapid change between two equilibriums for a system--like a reaction and like an excited electron, for instance. Venus is known to have undergone a planetary wide "supervolcano" event, resurfacing most of its surface. Earth, too, can and has supernovaed. Seen from the angle of Earth, however, it is instead the transition that occurred when the Earth went from a single landmass where all continents were conjoined on a smaller radius globe to its present radius with newly formed ocean beds. It is a cornucopia of fundamental truths to the nature of reality stored in the immense detail of the Earth for us to study and apply multidisciplinary analysis of its truly awe-inspiring beauty and capacity to teach us what we as a society seek to know. It is even a molecule, able to reveal nuances of chemistry unfathomable otherwise. It is in these ways in which the ice ages can be better understood. It is difficult to really elaborate on what benefit this approach could possibly provide to the topic, but without it there is no way to truly uncover what occurred. Earth supernovaed unequivocally, in my estimation, between the period of ~550Ma to ~12,000 years ago or of that magnitude. This caused rapid radioactive decay (a supernova is considered the decay of all the atoms of a star) while it went between two equilibriums (it is now largely stabilized), so what the actual time frame was is unclear. A supernova has a build-up "slow phase" and a rapid expansion phase--so did the Earth, with the rapid phase beginning when all the continents were so stressed from pressures upwelling below the crust that they spontaneously broke the remainder of what was necessary and internal pressures were able to stabilize as the ocean floors were largely formed during this phase, which occurred at the K/T Boundary. Like a true radioactive decay process, it did not just do a single step but it went through several transitions, and based off the K/T boundary and its relationship to the ocean floor spreading (many anomalies such as the average age of ocean crust ~65Ma, hydrothermal vents changing at the K/T boundary in technical ways and other details) which indicate a tie between the extinction events and steps in the Earth's "supernova", then all extinctions would be steps in the decay process of the Earth. In all likelihood, these ice ages are tied to nuances of how such a process manifests, if we were able to "zoom in" on atoms and watch them react in more exact ways. The periodic table does not capture the depth of detail of the surface of an atom. We do not describe them as being as nuanced as the Earth, nor the Earth as simple as an atom, but if we view it as possible then it would mean the ice ages to be tied to the radiation released when an atom radioactively decays, almost like a built in stabilizing process for when something goes especially haywire in the system. Pardon me I know I probably am very difficult to follow. However, these types of astronomical relationships I would suggest to be far more important than traditional considerations. :)
My favorite phrase “I study . . . rocks.” Steven Stanley, one of the authors of Earth System History, wrote a book, Children of the Ice Age, in which he hypothesized that the rise of the Isthmus of Panama 3 Ma created the environmental conditions in Africa favorable to bipedal apes, Australopithecus, an eventually to us.
What about the iron-60 signal, produced from a supernova appr. 3 million years ago, which can be found in rocks from the ocean floor? Cosmic events as triggers for an ice age?
Yes, impacts can cause what are called 'impact winters' due to the dust that they throw up, but over the long term they tend to cause warming due to the relatively fast rain out of the dust and the longer termed lifetime of the CO2 in the atmosphere that get's released during impact. :)
Tree ring sequences in some parts of the world have gone beyond many times the lifespan of the local trees, by way of tree ring matching between trees that lived during various overlapping times. Ice from glaciers in different parts of the world can be sometimes be matched from when individual volcanoes left behind some particular type of particulate deposit in the ice. In theory, the same general technique might be usable by stromatologists (rock layer scientists) to match thicknesses of various rock layers in approximately the same shore region of a lake or sea. Shorelines move, especially if a change in lake or ocean level happens, but certain events can leave traces in the sediments that tell a story that a rock layer was laid down in approximately the same year. Also potentially occasionally helpful is that annual growth layers in a small fraction of stromatolites from hundreds of millions of years ago indicate that even then, the solar intensity cycle was close to the 10 2/3 year solar intensity cycle of modern times. In order to find good evidence of a cycle of some sort, it is best to have a series stretching 3 or more times the cycle length. 32 years or longer is good for indicating an ancient 10 2/3 year solar intensity cycle for example, but is not good for indicating an ancient cycle lasting 20,000 or so years. It is very unlikely that annual layers lasting 60,000 or more consecutive years can be found in any one rock or in a series of age matched rocks to verify some ancient 20,000 year cycle, but that is the way such verification from the rock record would have to be done. Also, in ancient times, Earth rotated faster, and the Moon orbited closer, affecting how many thousands of years Earth's axis took to complete a cycle. If ever such a geological feat could be performed akin to the feat of matching annual tree rings, a hint would result regarding how close the Moon was at that time and how fast Earth rotated at that time. One other hint in the rock regarding a roughly 20,000 year cycle would be a slight shift in the ITCZ during the Summer. If perihelion happens in January, Summer monsoon rains are less likely in the Northern Hemisphere for example than if perihelion happens in July, with a July perihelion resulting in more extreme Summer heating in the Northern Hemisphere that makes Summer monsoon rains more likely in the Northern Hemisphere. Of course, in order to count how many years there were in that type of cycle, 60,000 years of consecutive (or close enough to consecutive) annual layers are needed from the rock record, something that is unlikely to be found in rocks more than a million years old. Adding a little bit to the trickness of the time of year of perihelion is that the ellipse of Earth's orbit gradually rotates, as a result of Einstein's theory of relativity. It is not just the axis of Earth that rotates.
Here`s our main problem. The only reason our current civilization was able to form was a highly unusual period of climate stability (see ice/mud core data) that has no chance of continuing. We could be preparing for what`s coming but absolutely no effort is being made to do so besides some seed vaults. 4800 years ago there was the Burckle Crater impacts and mega tsunami plus a global downpour of rain, then the 536 A.D. catastrophe, the Hopewell Airburst, The Year Without A Summer and other events being discovered including massive solar outbursts 100,000 times more intense than the Carrington Event and heat and apparent blast damage to megalithic structures around the world. These things are deadly to modern humans in several ways. They will happen again. But we`re obsessing over a slight rise in temperature when the data reveals very rapid temperature changes in the past of up to 15 C (up or down) in under 100 years plus the info above. We`re all sitting ducks and nobody is talking about reality. This is all temporary.
@@baneverything5580 , disasters sometimes happen on a worldwide scale, and occasionally those disasters are separated by less than a decade. The first volcanic interruption of the military attempt by Belsarius to reunite the Roman Empire happened in the year 536 CE, a year that you mentioned as a year of natural disaster. Armies that have little food cannot march, but still have to be paid. About 4 years later, another large volcano caused a second agricultural disaster in the Northern Hemisphere, in practice dooming the attempt to reunite the Roman Empire. You are correct in asserting that the modern early 21st Century worldwide economy does not have sufficient just in case food inventory for a repeat of either one of those two Northern Hemisphere agricultural disasters that happened in the first half of the 6th Century CE, agricultural disasters that were both caused by volcanism. The longer lasting ancient civilizations understood the need for gradually building up food reserves sufficient for surviving one very bad harvest year happening in a 10 year time span. The unfortunate current scheme of globalized economy in the early 21st Century does not make such a just in case food inventory scheme economically viable. Various lessons in government practice from the time of the ancient Roman Empire and the time of the ancient dynasties of Egypt have been unfortunately mostly forgotten. No longer exists anything remotely like the ancient government practice of setting aside some substantial fraction of the harvest from a good harvest year for future consumption after some bad harvest year that was almost inevitably going to eventually happen.
@@wendydelisse9778 Yes, there were two volcanic signatures in the ice core data several years apart...one at both poles. And there may have been space impacts too around this time. Diamond on Oppenheimer Ranch Project and Magnetic Reversal News had recent podcasts examining all the evidence and he was on Leak Project discussing it. Worth checking out. A huge volcano in El Salvador also erupted in 535-536 and a writer in Indonesia said an eruption "split Sumatra in half." The Chinese and Europeans reported massive booms. A huge volcano in Iceland and possibly even Alaska erupted as well and comet fragments may have exploded in the atmosphere. The evidence is very frightening.
@@wendydelisse9778 Hundreds died in Texas from a surprise power outage during a Winter storm. I started preparing days before here in Louisiana. Ice Storm = Power Outage. And we had one too. It got down to 2 degrees here but we had gas heat. Plus I have solar power that can run an electric blanket unless there`s no sun for three weeks.
@@wendydelisse9778 Imagine a worldwide freeze and power outage. Ice destroying trees and power lines and snow and ice caving in homes or burying them and the roads.
I would really like to understand why you seem to think carbon dioxide is a potent greenhouse gas, when its opaque to only an extremely narrow band in infrared, especially the broad band EM that water vapor blocks. Also, there's not much of it, compared to water vapor.
While water vapor has an overall much larger greenhouse effect than CO2, it remains relatively contstant with only minor fluctuations through time. Whereas, CO2 (in part because it is present at much lower concentrations than H2O) fluctuates much more drastically through time with changes in the burial v. emission cycle of C. Thus, these fluctuations cause temperature to fluctuate. We see these two parameters parallel each other time and time again on ancient Earth with independent reconstructions of both temperature and CO2 concentrations. It's also important to remember that it is not the magnitude of CO2 in the atmosphere nor the magnitude of temperature change that makes climate change harmful to life, it is the rate at which the CO2 concentrations and/or temperature changes. Thanks for the question, hope that helps! ;)
@@GEOGIRL I am of the opinion that extra CO2 in the air is actually very good for life, as there is direct evidence from satellite observations that plant life is growing better, especially in arid environments. Plants, being an autotroph, bring more food for the heterotrophs in most natural environments. More food, more life. I can find a source for that, but I think I gleaned that one from the IPCC AR5 or 6. Not sure, but it's hypothesized that plants are able to manage water more effectively with higher CO2 concentrations.
@@GEOGIRL furthermore... You did not address the relative strengths of H2O to CO2 absorption... Physically, CO2 is an ineffective infrared absorber and there is just not that much of it. The extra CO2 gas in our atmosphere can't make the troposphere any more opaque to infrared than it already is. Take a sheet of aluminum foil. That's opaque to visible light. Now add in a few atomically thin sheets of copper atoms. Is the aluminum-coper now MORE opaque? No... I think it's reasonable to say it this way, an infrared photon emitted by the ground gets absorbed by a greenhouse gas molecules. The odds are extremely in favor of being absorbed by H2O unless it wins an extreme lottery. Something like a billion to one. But alas, if the CO2 wasn't there, it would just get absorbed by the H2O molecule anyway. I don't deny science, I am just really skeptical of this global warming alarmism that's going around... Ocean Acidification.
@@GEOGIRL besides... Couldn't the variability of CO2 be caused by ocean temperatures? Colder ocean, there's less CO2 in the air, warmer oceans, solubility of CO2 is lower... It's the CO2 follows temperature hypothesis, I have not heard much evidence against this idea.
@@kayakMike1000 Well, the hard thing to do with the 'temperature first' hypothesis is find the trigger? When we think about CO2 caused temperature change in Earth's history, it makes sense because an asteroid impact or a volcanic eruption burns a bunch of carbon deposits and releases it to the atmosphere as CO2, then temperature rises, we see this consistently in the rock record. Likewise, when period of major O2 increase occurred due to the evolution of photosynthesisers, we see that that major cooling periods happened as a direct result of the carbon uptake and burial by such organisms. Thus, atmospheric carbon increases and decreases can easily explain the temperature variations we see in Earth's history and we know what triggered these fluctuations, whereas, we do not know what would trigger a temperature variation if carbon fluctuation did not come first. There is of course possibiliies of astronomical effects that could cause temperature fluctuations, but these have been considered for all past climate change events and in most cases are shown to likely have only played a small role if that. I hope that makes sense ;)
Whoa I had no idea that we're currently in a Quaternary ice age. Although it's hard to tell since it's been so freaking warm these past few days. Anyway those ice ages you talked about sound intense.
There is a conjecture that the Ordovican glaciation (Andean-Saharan) might be related to the Ordovician Meteor Event which showered Earth with L chondrite meteorites that are prominent in the geological record of the Ordovician. The idea is that the parent body of L chondrite meteorites (an asteroid in the main belt) was destroyed in a collision 467 Mya, producing both the meteorites found in abundance then in Ordovician strata, and also (possibly) a cloud of dust which scattered sunlight and reduced the solar constant a little, contributing to the Ordovician glaciation. The Ordovician Meteor Event is fairly probable, as we have the meteorite evidence and the L chondrite parent body has not been found in the asteroid belt. But the cloud of dust and its affect on Earth's climate is more of a conjecture, as there seem to be competing explanations such as non-vascular plant growth taking up CO2 and burying it. I don't know whether there are proxies for atmospheric CO2 level that show CO2 decreasing before and during the Ordovician glaciation, but this conjecture would imply a cooling trend that was *not* caused by CO2 decrease, but instead by lowered solar flux at Earth -- so maybe it is possible to rule this idea out.
I've been wondering if there's a connection between ice-ages and the cyclic nature of climate in the Sahara desert? It used to be full of lakes and savannahs, but they all dried up. Scientists project that in many thousands of years, it will be wet again. Is there any connection?
11:32 If I just could find someone to explain to me in a fashion comprehensible to a layman, why a change in earth's tilt affects average global temperature. After all, the surface area exposed to sunlight remains the same - so the amount of energy should remain the same on a global scale. It may change seasonally - but what you get less in wintertime, you get more in summertime, as the tilt increases. Same for the "wobble".
@Geo Girl you stated CO2 traps heat. Can you explain something for me? The Sun's radiation is converted into thermal (kinetic) energy in the atoms and molecules of the surface and in turn the surface cools by conduction and convection transferring thermal energy into the atmosphere. CO2 interacts with a small range of photons and converts their energy into thermal energy. This occurs within a few metres of the surface. If it did not convert radiation into thermal energy the temperature would not rise. My question is how do the laws of physics know to trap the contribution from CO2 whilst allowing all the thermal energy created directly by the Sun to escape to Space?
I am certainly not a physcist by any means ;) but it's my understanding that the CO2 contribution isn't fully or preferentially 'trapped' but rather that when the radiation from earth to space goes through the atmosphere, some of it escapes, while some interacts with and is scattered by CO2 (and other greenhouse) molecules in the atmosphere. This scattering of the thermal energy basically blocks its escape and keeps it in Earth's atmosphere for longer. There has always been CO2 in the atmosphere so this has always occurred, but with increased CO2 concentrations, there is an increased amount of IR radiation that hits these molecules on its way back to space, leading to increased thermal energy remaining in our atmosphere for longer periods at a time, aka warming. I hope that helps a bit, I know this doesn't fully answer your question from a physics point of view, but hopefully a physicist will comment on this thread to enlighten us! :)
@GEO GIRL A greenhouse demonstrates that very little radiation from the surface goes directly to Space. Experiments comparing two greenhouses, one with glass that blocks infra red and one with quartz glass that does not only show a small difference in temperature. The glass is blocking all the infra red whilst CO2 only interacts with a fraction. The physics of the Greenhouse effect relies on the majority of surface cooling due to radiation. If this was true, then the two Greenhouses would differ much more in temperature. If a surface cools mainly by radiation rather than conduction and convection, there would be no point in vacuum flasks. I think we are being misled on the issue of CO2.
@@wrath276 Well it's like you said the glass blocks it all and CO2 only interacts with a fraction. That still stands in the atmosphere. It is not that CO2 in the atmosphere either creates this effect or not, it is always blocking a small fraction of radiation from escaping, it is just that as CO2 concentrations increase, that fraction increases, and when it is a global phenomenon, the fraction of radiation blocked does not have to be significant for the overall global change in amount blocked to be significant during periods of increased or decreased greenhouse gases to the atmosphere. It is all relative not absolute. :)
@@GEOGIRL The key point you are missing is that the Greenhouse Effect is required to trap so much radiation that it raises the Earth's temperature from minus 18C to plus 18C. This just not feasible if only a small amount of surface energy is lost by radiation, the vast majority being transferred into thermal energy. You cannot trap radiation, it either escapes to Space or converts to thermal energy. What is important is the physics of how thermal energy in the upper troposphere is converted back to radiation so that it can be lost to Space. CO2 can operate in the reverse process by which photons are converted to thermal energy. If it is stimulated by the right amount of thermal energy it can emit a photon. So any increase in CO2 is self cancelling. I am still trying to find out how the vast amounts of thermal energy in Oxygen and Nitrogen the Sun creates daily is also converted to radiation. As an aside have you considered where all the free Oxygen in the atmosphere came from. Oxygen is highly reactive so it will not occur naturally. Life has spent 2.4 billion years separating the Carbon and Oxygen in CO2, the Carbon locked away in shells that become the white cliffs and coal created from ancient trees. There was only 0.028 percent CO2 left in the atmosphere by the 1900s Life was running out of fuel. When CO2 falls below 0.016 then most plant life cannot flourish. If CO2 traps heat it's hard to see how a planet with 70 percent of its early atmosphere as CO2 could evolve life as the oceans would have boiled away putting even more Greenhouse Gas into the atmosphere as Life had to start to enable the amount of CO2 to come down.
@@wrath276 I don't think anyone ever claimed that CO2 changed global temperature 36 degrees C. I think the most people argue that rising or falling Co2 causes is a few degrees C over decades if not centries/millenia. The thing that the greenhouse effect does do is trigger further warming or cooling, which is then exacerbated by positive feedbacks like decreases or increases in Earth's albedo, or methane hydrate melting feedbacks. The positive feedbacks are what lead to drastic temperature changes, but they wouldn't have been activated without the slight change in temperature caused by initial changes in CO2 concentration. :)
This is very interesting. I hather that the pleistocene icesheet protrusions in Europe (ie the weichselian and others) are not considered separate ice ages? Regards.
Well done on the Phanerozoic! 😊👍🏻 Please don't get mad. A couple of things. Let's get the nitpick stuff first. Saying Huronian glaciation is technically incorrect. The Huronian is a lithostratigraphic supergroup. Not a time period. It would be like calling the Quaternary ice age the Wedron-Mason glaciation. Now for the more technical. There is no solid evidence that the Huronian deposits were from a snowball earth. It's like every time we see glacial deposits in the Precambrian we leap to snowball earth. We have no solid evidence that the Paleoproterozoic glaciations were a snowball event. It's a complete assumption based of a bad Wikipedia article. The article wasn't even written by geologists. I tried to fix it but the damage is done. The Huronian Supergroup consists of 4 groups and shows three main cycles of glaciation. The bottom group has zero glacial deposits. The direct and indirect glacial deposits only make up 11% of the supergroup and the deposits are no thicker than modern marine glacial deposits. There's no cap carbonates either. Most of the Huronian is passive margin deposits similar to the coastal plain deposits of today. Indicating warm climate. We do have some paleomag data from that time. However it's 30-50 years old. So we don't even really know where the continents were located at the time. Everyone is so focused on Rodinia right now, that I don't see it happening any time soon. I did a whole video on our misconception of the Huronian deposits about a year ago. I don't even know. LOL.
Oh that is so interesting, the things I read called it the Huronian glaciation, I guess they thought using the group for that one was easier considering the lack of well defined periods that long ago..? In any case, thanks for the clarification here! I'm gonna have to start watching your videos more often ;) If anyone is interested in a super in depth video on the Huronian here's the link to one of Steven's videos on it! -> th-cam.com/video/bpIQhClkWcA/w-d-xo.html
@@johnvoelker4345 like o said. It's technically incorrect. No they don't. Maybe on TH-cam. We all say Paleoproterozoic or Soderian because it was global. The Huronian is only in North America. Just because a lot of ppl say it doesn't make it correct. It violates the North American stratification code which is the standard we use.
If humans had continued to live like they did 10,000 years ago, how long would they have before glaciers started forming and moving south, again. 5,000? 10,000 years?? As we are, today, will we stop, or just delay the start of serious glaciation?
I don't know for sure, but I think I remember coming across something that if not for human-caused climate change, our inter-glacial warm period would probably be starting to close by now
We are past (in regards to Milankovitch cycles) peak insolation at the high latitudes so yes, without human interference there would be a sligh cooling at the high latitudes and possibly glacier building going on in the upper most regions of Canada. We've not only assured that is not going to happen, but it looks like we're going to significantly melt the remaining glaciers in Greenland and Antarctica.
Hopefully, seen on a long run, the inevitable change from our present milder ice age state into a warmer one (presenting no permanent ice on the poles) comes smoth enough, so that we don't have to loose so much of all that magnificent biodiversity which makes our world so fascinating.
We also really need to look at the times when the Earth suffered a supervolcano eruption (Level 8 or higher on the Volcanic Explosivity Index or VEI). The Toba eruption from around 73,000 years ago may have blocked out the Sun worldwide for over a year and may have triggered off an Ice Age that may have taken a couple of centuries to get the Earth back to normal, with a resulting small scale mass extinction event.
As I understand it, to account for the two-mile thick ice sheet and much lower world-coast lines of the last ice age, before the great melt-events (e.g., of Lake Missoula), you need the evaporation of roughly 320 meters of the (entire) world ocean. For this one requires a MASSIVE source of HEAT (e.g., a chunk of star from a super nova...something such...passing by). Needless to say, this is none of the five sources listed, and none (as far as I know) are commensurate with the heat/evaporation required.
Hmm, what causes ice ages? How about Dansgaard-Oeschger events causing Heinrich/Heinrich-Bond events? Previous Dansgaard-Oeschger events have raised the global temperature 8°C (14°C?) in only 40 yrs (long, long ago). Dansgaard-Oeschger events are followed by Heinrich/Heinrich-Bond events, which get very cold (ice ages).
Atmospheric H2O is the dominant greenhouse gas, and all other greenhouse gases combined are minute compared to atmospheric H2O. Animals that have exoskeletons or shells have "buried" more carbon than all other causes combined, especially those tiny animals of the oceans. The planet warming causes increased atmospheric CO2, not the other way around, due to ocean off-gassing.
Neglected to explain what an ice-age is. Via Wikipedia, An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which periods there are no glaciers.
To "do the Calculus" of creating prior states of NOW, from the be-cause-effect of e-Pi-i QM-TIME Completeness, in self-defining nodal-vibrational matrices of emitter-receiver log-antilog inclusion-exclusion, resonance timing-phases, vertically integrated harmonic/holographic positioning.., first principles reasoning process requires the idea that it is always NOW, and one has to prove it by moving positioning back and forth to differentiate between different states of time-timing sync-duration and distance, from clock timing rate of "temperature", to speed of travel ratio-rates, in a holistic Perspective, what you think you see is correspondence of Mathematical and "Musical" quantization-bonding, or reciprocation-recirculation of pure-math relative-timing ratio-rates "Circuitry". Applications of this POV will require a literal shift of focus to work on complex issues like Ice Ages, but this was an excellent presentation to begin reiteration.
The hypothesis that CO2 is a driver of climate is flawed. It is rather a lagging indicator of global temps. Simple example: Cold beer got lots of CO2 bubbles....warm beer don't.
During recent glacial/interglacial cycles it has been both. During Milankovitch-forced cooling, CO2 becomes increasingly sequestered in cooler ocean waters and in permafrost (the area of the latter, presumably, increases as the neararctic regions shift toward the equator). At the end of a glacial period (again, initially due to Milankivitch forcing), CO2 is liberated back into the atmosphere, and (along with decreasing albedo) accelerates the warming trend (in a feedback loop), until a new equilibrium is established as an interglacial. The current understanding is that CO2 never exceeded ~270 ppm even during recent interglacials, but since the Industrial Revolution has increased to the present 400+.
@@sinkrock1 HUH ? References/Context needed: She's probably just calling out the folks who claim that "climate has always changed", failing to differentiate between past and present.
The only reason our current civilization was able to form was a highly unusual period of climate stability (see ice/mud core data) that has no chance of continuing. We could be preparing for what`s coming but absolutely no effort is being made to do so besides some seed vaults. 4800 years ago there was the Burckle Crater impacts, then the 536 A.D. catastrophe, the Hopewell Airburst, The Year Without A Summer and other events being discovered including massive solar outbursts 100,000 times more intense than the Carrington Event and heat and apparent blast damage to megalithic structures around the world. These things are deadly to modern humans in several ways. They will happen again. But we`re obsessing over a slight rise in temperature when the data reveals very rapid temperature changes in the past of up to 15 C (up or down) in under 100 years plus the info above. We`re all sitting ducks and nobody is talking about reality. This is all temporary.
"Each period of 1200 years begins and ends with a catastrophe; human evolution expands and grows in the space of two scourges. Fire and water, the agents of all material mutations, work together during the same amount of time and each on an opposite region of the Earth."
Ask Frasier Crane the question about predicting Earth's past orbits. If I remember, I'll ask the question and point to your channel. If he doesn't know he's got great friends.
@grindupBaker Yes, more ice growth. But will the ice shield cover the poles or will there be an ice free zone directly at the poles? After all the closer you get to pole the longer your polar day gets (up to full year at 0° tilt).
Um, we're already in an Ice Age dear! It's called the Quaternary. Are you talking about a glacial cycle? If so, the next one isn't predicted to start for another 50,000 years or so!
agw = anthropogenic global warming Statistically, more CO2 has a high "positive correlation" with higher temperature during the last 280 million years on Earth. Mankind has apparently increased the sea level partial pressure of CO2 by about 30% in the 120 years that has passed since time that the automobile assembly line and the airplane were invented in the year 1903. Since 1903, the statistical correlation continues to be good between higher sea level partial pressure of CO2 and higher temperature.
On an in between time scale of 66 million years, see "Atmospheric CO2 over the past 66 Million Years from Marine Archives", in the May 2021 edition of the Annual Review of Earth and Planetary Sciences. The authors seem to agree in the abstract portion of that paper that there is "coupling" between CO2 and climate during that time frame. Back in the mid-1800s, Tyndall very publicly demonstrated the blocking effect of CO2 on infrared radiation, and numerous studies based on the geological record back up Tyndall's 19th Century findings. Angstrom also did some work in the very late 19th Century, with regard to the infrared blocking effects of CO2 and water at a temperature near the 100 degree Celsius boiling point of water. Angstrom's work might potentially have some bearing on the greenhouse effect of atmospheric water during the Haldean Eon. Overall, the geological record agrees reasonably well with greenhouse effect theory. However, in the 1930s, Guy Callender noted that the greenhouse effect was progressing slightly faster than expected during the early part of the 20th Century. As such, historical record (and geological record as well) can be said to not be in full quantitative agreement with greenhouse theory, but are in excellent agreement from a qualitative point of view. Unfortunately, Callender's work still seems to be under copyright, and as such TH-cam channels are afraid of quoting from his paper. Qualitatively, in a modern Earth-like atmosphere with a solar constant similar to that of modern Earth, more CO2 means more greenhouse effect.
@@davidrogers8030 that studys numbers been debunked. There are plenty or world class scientists in many subjects that don't agree with weather czars like al gore
we could map heavy objects with gravitational wave monitorring and invert time in a cmputer but you would need a lot of points of refrence at steeeeeeeller or at least planetery distances
I’m impressed by your study and rendition of accepted science. This video stands alone in a sea of “climate science” available on this platform. However, some of your statements about CO2 in times past, while extracted from the literature on this subject, are suspect. Climatology is a field that has lost its way. The very oldest actual observations of atmospheric CO2 are 1.7 maybe… 2 million years old. These come from gas trapped in ice cores. And such ice cores are very very limited. Partially due to the scarcity of ice that deep and old, partly due to the limits of our ability to drill that deep. So the information you provide about CO2 and it’s effect on atmosphere waaayyyy back is based upon proxy data and computer models. Not on actual observations. Now 30 years ago if I was to suggest that such model projects were weak, I would be crucified. In fact I was. Repeatedly. Today that is not the case. Time reveals all. And time shows that computer projects of 20-30 years ago are off. Way off. So far off that those dedicated to the proposition of global warming by CO2 remain strangely silent now. The green house gases are moderators of what is a much larger physical process. Over the last 3 million years, some suspect 7 million but can’t prove it, we have been in this “ice age”. This is deceptive. In reality we have oscillated on a glaciation cycle with a period of 150,000 to 175,000 years per cycle. This cycle is defined by the Milankovitch cycles you allude to. Within each cycle is a glacial maximum followed by a glacial minimum. We are now in the minimum and still warming slowly. Statistically we have another 15-20,000 years before cooling again begins. Our observed weather data, compressed into climate data is consistent with this pattern based upon previous cycles seen in the ice cores. Green house gases are simply not as effective as the majority contend. Put them back under the bed with the other childhood monsters and examine the facts. Sadly the facts are not widely available today. Science is based upon self evident observable facts. Not “proxy data” and general consensus. If it were not Galileo would have been burned for heresy and we would still live with the earth as the center of the universe. But that’s not the case. So question your “facts” about the greenhouse gases. Do they work. Yes. We’d not be here without them. But they are the tail, not the dog. Don’t let them wag you so. Over all a very good presentation. Fox out
My actual PhD research is on refining our geochemical proxies for reconstructing Earth's history so I am well aware that everything presented here and in most of my videos is based on proxies :) But because that is my area of expertise I sometimes forget to make that clear to the viewer, and that is my bad. That is actually the reason why I mentioned in the pinned comment I would like to make a future video about how we reconstruct Earth's history (so basically a video all about how we use and refine proxies), which I hope will provide some much needed context for the rest of my Earth history videos :)
@@GEOGIRL I see it now. I also see I underestimated you. Flipping about, discovering a channel. A doctoral student no less. And me using a tooth brush that is probably older than you. Well I have subscribed. Let’s see where we go. Maybe I can keep up! Fox out
Haha, sorry I should've made this more clear as well. These are just the most widespread ice ages throgh Earth's history based on the current knowledge of the rock record. However, this list can change over time with new pieces of evidence for these and other events. :)
CLARIFICATION: I got a lot of comments on my previous 'Was Early Earth More Extreme' video saying that the ~2.4 billion yr ago snowball Earth does not have as robust evidence as the later ~700-600 snowball earth events. I should've made that more clear in that and this video, so I am writing this comment to clarify that Earth history is really well studied and we have been able to reconstruct many events and trends through Earth history with a multitude of corroborating lines of evidence, but some events have less evidence backing them up than others. This isn't because these events are less studied, it is most often because we have a patchy rock record and some periods in Earth's history are just not preserved as well as others. So just please understand that everything I discuss regarding events in Earth's past are hypotheses and sometimes I forget to use words like potentially or possibly. But also be aware that many ancient events are very well backed up with many lines of geochemical and paleobiological evidence, and people (including myself) work everyday to refine our methods of reconstructing Earth's past. :)
These comments actually inspired me to work on a future video about 'how we reconstruct Earth's history', the specific geochemical methods we use to figure out what happened in Earth's past. Let me know if that's something you'd like to see! ;)
Yes! That sounds like an excellent topic for a video, or probably a series of videos. Oxygen isotope ratios vs. periods of glaciation, trace metals, iron oxidation - plus the environments where these changes in geochemistry occurred, deep vs. shallow marine. It’s a lot of puzzle pieces to put together! Something like that sounds like a perfect idea for pulling together the knowledge you’ve shared in a lot of your previous videos. Go for it!
It is.
definitely want to see a video about the methods topic. 🎉
Yes, big YES on a video on geochemical methods. Yours are the best vids on geology on YT IYAM, Rachel, & some of the best science vids period. Thank you again for your great work.
History is simply the current best explanation by the evidence in hand. No one should get their feathers ruffled over it - especially exact dates.
Oh, and I might've missed this in your video, but the strength of the magnetosphere determines how much radiation enters the atmosphere. So does CO2 determine global temps or does the CO2 level follow temperature changes?
We're at 415ppm of CO2 now (or about .04% of atmosphere) & below 150ppm everything dies. Why is there a war on plant food?
As a kid I have never been Interested in geoscience or geology. This has changed so much in the last year because of interesting results from geophysics (early earth formation, moon creation, climate change, stratospheric cooling physics) and above all because of your channel. I really owe you a bigger picture of the world. I wonder if the statement that solar and planetary physical influences on the climate are less “real” should mean “less tangible in rock history” - given the formidable improvements in computer simulations, there must be evidence on evolution or changes in earth dynamics. Capo for your excellent science communication and your intelligent deep dives. Don’t change anything! (please no music at the end).
Fascinating stuff! The history of this planet is so much more complex than folks generally acknowledge.
Just came across your channel yesterday and as someone who has enjoyed prehistory for most of my life it was an instant subscribe. Thank you for creating these informative and educational videos! 👏✨
Thanks!
Thanks so much! ;D
A few pedantic suggestions:
1) in the graphic (first one at 3:00) change "excentricity" , which is a term that has popped up in some social commentary, with the proper spelling);
2) regarding the "tilt" - the poles receive less solar radiation _at the annual maximum_ (summer solstice) when there is less tilt. Thus less summer melt.
The Milankovitch model suggests that the dominant factor in variations should be the 41,000 tilt cycle, as tilt has the greatest effect on seasonal intensity. Oxygen isotopes have shown that, for the last ~800 kyrs, the 100 kyr cycle has dominated though orbital eccentricity should be the weakest factor.
I bring this up because I remember seeing a talk ~30 years ago by a Berkeley physicist (whose name escapes me but he had worked with Luis and Walter Alvarez on the impact hypothesis) who suggested that there is another 100,000 year orbital cycle: this cycle occurs when the Earth's orbital plane periodically lines up with the solar equator, during which there is a marked increase in the amount of dust in our orbital lane that reduces overall solar intensity. He suggested that this might explain the dominance of the 100 kyr cycle.
I've not heard this since that talk and I'm curious if you or your community of subscribers ever recall hearing this mentioned...
The change from 41K yr ice cycles to 100K cycles beginning ~1M yrs ago, the 100K yr problem, even has its own Wikipedia page. A number of hypotheses have been proposed.
The Sturtian and Marinoan glaciations are named after 2 localities close to Adelaide, South Australia. The Sturt Tillite can be found in the Sturt Gorge Recreation Park, but is really widespread across the state. The Antarctic explorer, Douglas Mawson was involved in research to date these various glaciations. It seems he had a life-long connection to all things glacial!
Congratulations on 30K subscribers! You’ve deserved each one!
Thank you so much! ;D
@@GEOGIRL Thank you for your content. We need more good science communicators :)
Dude she deserves 3 million subs, not just 30K
The pointing in your thumbnails really helps. I'm new to this looking at stuff business and sometimes I just don't know where to start.
Hi there Geo Girl. Another excellent presentation :) I always learn something new. I'm glad you mentioned at the outset that Earth's climate has warmed and cooled throughout it's long history. As I believe you've said before, climate and such is a very complicated process. The approach needs to be opened-minded and not forced into a politically motivated box. About the Milanković Cycles, would you happen to know if they began to affect the planet beginning at the Late Eocene Epoch when Earth began to cool, or was it not until the beginning of the Pleistocene? To me this seems to be a rather complicated time in Earth's history. Besides the advent of cooling, there was also the Eocene - Oligocene Extinction Event, and the Chesapeake Bay Bolide Impact Event. I am of the opinion that these are all somehow connected, but this is not one of my areas of knowledge. gfs
It wasn't until the Pleistocene that they really started to cause major interglacial cycles. It is complicated, like you said there are so many factors at play and it is also difficult to interpret small trends (like interglacials) within larger, longer more gradual cooling or warming trends. I actually have a video on the Eocene-Oligocene Extinciton (th-cam.com/video/Eq4Dx-JPBuE/w-d-xo.html), and I think I mention that impact in that video as well, but I can't remember that might be in a different video haha ;)
I also agree about the complexity of climate change throughout Earth's history and on modern Earth, it baffles me that people try to make it political in any way...
I've sent you a note (ta-da) via your website :)
@@GEOGIRL I just don't think it has anything to do with CO2. The data just doesn't present any evidence that climate changes is caused by CO2. Well, the data I could get, at least. It's hard to get actual data from the climateers anyway.
We can actually reconstruct past orbital conditions. The nice thing about Newtonian mechanics is that it’s really easy (relatively) to predict how planetary bodies will move in the future given enough data points. Knowing this knowledge, we can actually turn back the clock and give our best guess as to what the orbital conditions were. However, it’s hard to account for random events like giant impacts and such.
"We can actually reconstruct past orbital conditions. " - but the small errors at the initial conditions increase the uncertainty significantly in the out years past a couple of million.
Something to consider is the flight of the Sun through the regions of space around the galaxy. We fly around, and just outside one arm of the galaxy as the galaxy turns and we have been around that arm and rotated with the galaxy several times since Earth formed. Doing so, we have passed by many other astronomical bodies, great clouds of gas, intense magnetic and gravitational fields and turbulence from collisions with other, small galaxies. Time is very deep and complex things happen that are hard to trace.
@@fredwood1490 The spiral arms don't rotate as solid objects with the sun at a fixed distance from them. Spiral structure is more like a shock wave in the interstellar medium, delineated by star-forming regions containing young stars, some of which are very bright and short-lived, dying in supernova explosions.
The sun's orbit around the galactic center takes ~225 million years and should have carried the solar system through star-forming regions many times in Earth history. These passages through star-forming regions could occasionally bring the Earth close enough to supernovas to affect conditions on the Earth, and possibly Earth life.
However, in most of Earth history life was single-celled and the rock record is sparse, so it is very hard to tell when there were extinctions until the Phanerozoic. During the Phanerozoic, the sun has completed about 2 and 1/2 galactic orbits, and should have been near star-forming regions several times, but all the major and most minor mass extinctions in the Phanerozoic seem related to climate change.
@@ellenmcgowen Exactly, though I hadn't thought about the spiral arms being shock waves, it makes sense. My point being that there is a lot more to Earth's history than the bit we are living through right now. How many more "Snow Ball Earths" are lost in the rock records? How many gamma ray bursts? Life is said to have developed within the first billion years after our forming, but multi-cellular life not until the last billion years. Given the rate of change and development we can read in the fossil record, what held up that development?
Great presentation -- you have helped me to refresh and educate me. Thanks.
Amazing video, Very interesting.
Thank you for sharing.
Wonderful presentations. Thank you. It was your words that invited us to consider ice to be a rock -- which lead me to a few seminars found in the playlists of NASA Goddard Institute for Space Studies. Nice to see how ice moves... it is rock. (You are a Rock Star! )
An excellent presentation.
Hopefully papers or precis briefs are also in store.
Brilliant presentations. Not found this level of detail anywhere else. Thank you.
The solar system travels around the galaxy passing through areas with more or less dust and this also could affect climate by blocking sunlight? Don't know but recall seeing this suggested a couple of decades ago.
Your updates are perfect thank you geo girl
Geo Girl, thanks so much for your clear explanations. These are things that I've been wondering about for quite some time.
2:50 The diagram of Earth's elliptical orbit shows the Sun at the center of the ellipse. The Sun would actually be at one of the "foci" of the ellipse. This is important for thermal changes, because the Earth spends less time in the part of its orbit near the Sun, and more time farther from the Sun. Earth's orbital speed gets slower as it gets farther from the Sun. In very eccentric elliptical orbits such as some comets, they whiz past the Sun in a very short time, then slow their travel far from the Sun to spend decades to millions of years in the cold outer solar system.
3:44 For the orbital diagram in the video, the mouse cursor is used to show that the Earth is closest to the Sun at the shortest distance across the ellipse (along the minor axis of the ellipse). But the Earth is actually closest to the Sun at one side of the longest distance across the ellipse (one side along the major axis of the ellipse). This is because the Sun is not at the center of the ellipse, but at one of the foci of the ellipse.
New knowledge for me, thanks!!
Also the reason why the "figure 8" Analemma is lopsided from Summer to Winter. It would be more symmetrical if the orbit was sun-centered. In a perfectly circular, sun-centered orbit, the analemma would "collapse" into a north-south line.
Wow! Someone who presents the fact without having an axe to grind. Another factor in the effectiveness of the Milankovitch Cycles has to do with how much land there is between 30 degrees north and 70deg. north as opposed to how much open ocean there is in the same band of the southern hemisphere. This also affects northern hemisphere glaciation vs. southern. Land heats and cools faster than sea water.
Very nice video geo girl 🙂✨✨
Recently discovered geogirl. Love the content but the echo in the audio is really distracting. Can you run some software that sharpens the audio?
Thanks for the feedback! I have actually changed it since this video, so watch a recent video and let me know what you think. I think it is better now! But I don't have the audio ear, so having the feedback is helpful :)
well done, there are some pretty precise computer models that can show past cycles.
You must be super fun and informative on roadtrips! Especially say Banff/Canadian Cordilleras.
Dang girl you pretty,on the video topic now,nice bit of knowledge.
Nice vid.
Have a nice day.
Petition for “I dunno I study 🪨 “ t-shirt
So cool geo grl!🤙
FYI, I think Brian Cox mentioned it, we are able to recreate earth's orbit, and other planets orbit up until, allegedly jupiter was roaming chaotically around the sun. So we should be able to see exactly earth's position 3-4 billion years ago, but we can't really know earths position prior to that.
Interesting video thanks 🙃
Thanks for your class!
It would be nice if you made a similar video except that you try to extrapolate into the future. Based on what we know about the past, can we predict how changes in tectonics and all that jazz will affect the climate in the future? Like, when will the next major ice age or snowball earth happen? Or WILL it ever happen given all the carbon we're putting into the atmosphere and the fact that the sun is getting hotter? I remember hearing on another TH-cam video that with the sun heating up, probably all life on earth will end within the next one billion years. It might've even been shorter than that.
Oh that is such a great idea! Thanks! ;D
In about 1 billion years it can be expected that without any intervention all higher life will have ceased to exist on Earth. Though the demise will start way earlier. The luminosity of the sun is increasing and in about 500 million years it can be expected that the greenhouse effect gets unstable. Higher temperatures will increase the amount of water vapor in the atmosphere which in turn will lead to higher temperatures as water vapor is also a greenhouse gas. Though the real problem for life will not be the temperature increase but the increased weathering due to the increasing amount of (warm) rain. As a result the CO2 levels in the atmosphere will drop and will reach in about 900 million years the critical level where plants can no longer survive. Due to this life (or at least all higher life) will most probably be extinct long before Earth reaches the point where it enters a runaway greenhouse effect much like Venus (will happen in about 2 billion years).
Atmospheric water, in higher amounts from hot temperature, transports latent heat high enough into the atmosphere that there is little CO2 to stop that heat from then radiating into outer space.
At current conditions, the tug of war between on the one hand latent heat transport by atmospheric water and the Stefan-Boltzmann equation and on the other hand the greenhouse effect of atmospheric water is about a tie, explaining why in the last million years or so tiny changes in sunlight falling on Earth have made big differences in temperature.
In much warmer conditions, the extra heat carried aloft and then released by water turning into liquid or solid at high altitudes more than outpaces the extra greenhouse effect, meaning in practice that there is a cap on how hot Earth can get with a given solar constant, unless Earth's oceans dry up of course.
Earth did not turn into another Venus during the end Permian and go into a runaway greenhouse effect. Part of what was going on is that water is not a "well mixed" atmospheric component on modern Earth and as such, in practice the exponent for determining infrared optical thickness from water is lower than that of CO2. In addition, unlike with CO2, the exponent for water appears to decline with temperature, rather than staying close to constant over a broad range of temperatures and pressures. If the exponent for atmospheric water increased with temperature on Earth, or stayed constant with increasing temperature on Earth, Earth would have indeed gone into a runaway greenhouse state.
What can be referred to as mathematical "plate count" is about 3/4 of the infrared optical thickness, where each mathematical plate represents half of all infrared radiation escaping outward, and half being redirected inward. Fractional plates are possible, and are actually typical.
The greenhouse temperature multiplier is (1 + PlateCount) ^ 0.25, a mathematical expression in which the 0.25 exponent comes from the inverted form of the Stefan-Boltzmann equation, an equation that you can look up on the Internet if you are interested. The usual non-inverted form has the number 4 as the exponent. The mathematical reciprocal of 4 is 0.25, explaining why 0.25 is the exponent in the inverted form of the Stefan-Boltzmann equation.
@@wendydelisse9778 It sounds as though you have the ingredients of a 1-d model that could be run with increasing solar constant from stellar evolution of the sun to predict the time at which the oceans boil off.
The freezing point is more important than the boiling point. Mars still has some water away from the poles of Mars because that water is cold enough to normally still be in frozen form, and therefore is somewhat protected by being a part of the geology of Mars.
Earth does not have that protection of water being in frozen form away from the polar regions, and yet Earth still has an ocean cover fraction of about 2/3. Earth has a different protection insteas for its water, protection that is ultimately due to a ratio of orbital velocity about the Sun to escape velocity from Earth that is less than 3 to 1.
For retaining atmospheric dinitrogen in a no ammonia atmosphere within the orbit of Uranus, less than a 4 to 1 ratio is good enough for a planet-sized object, as is seen with Titan (3.66 to 1) and Venus (3.38 to 1) and Earth (2.66 to 1). (For a moon, use the orbital velocity about the planet instead if greater than the orbital velocity of that moon and its planet around the Sun).
To begin the explanation of the special protection that Earth gets for retaining liquid water away from Earth's poles, Moon astronauts orbiting the Moon some 50 years ago noticed a pre-sunrise diffuse glow, with their claims backed up by camera evidence. The molecular cause of that pre-sunrise diffuse glow is why Earth still has a substantial liquid ocean.
That glow comes from the scattering effect of a thin atmospheric veil of neutral monatomic hydrogen (chemical formula H1 or more simply H) that extends outward from Earth for about twice the radius of the Moon's orbit. Earth's gravity in relation to Earth's orbital velocity is strong enough to maintain a still conditionally visible veil of neutral monatomic hydrogen in spite of the effects of micrometeorites and solar wind, and is part of the explanation for why it took Earth billions of years to lose enough hydrogen atoms for dioxygen (O2) to be present in greater than trace amounts in Earth's atmosphere. Hydrogen atoms were escaping to beyond the mesopause, but a fairly large number of hydrogen atoms were also coming back in from that thick enough and broad enough veil of neutral monatomic hydrogen.
As dioxygen (O2) and ozone (O3) partial pressure rose, the escape to capture ratio of hydrogen atoms by Earth attained approximate chemical equilibrium of 1 to 1 when dioxygen partial pressure at sea level got to about 25,000 pascals. Oxygen binds very tightly with hydrogen, and so the presence of greater than trace amounts of free oxygen on Earth, in combination with Earth's thick enough and vast enough veil of monatomic hydrogen, allows Earth's oceans to retain their hydrogen atoms.
Higher temperature from a higher solar constant will mean that more dioxygen will form as some hydrogen atoms gradually escape from Earth as a result of higher temperature assisting the dissociation of water molecules, thus restoring close enough to a new equilibrium that would still allow Earth to retain most of its ocean water. Ultimately, that higher future partial pressure of dioxygen will possibly become more of a threat to life on Earth than rising temperature.
Short version: Earth's oceans have good enough protection from losing their hydrogen atoms, due to the presence of a thick enough and vast enough veil of monatomic hydrogen that extends from Earth to beyond the orbit of the Moon. For Earth, the big long term threats to life forms are instead rising temperature and the resulting greater partial pressure of free oxygen, rather than the loss of enough hydrogen atoms to cause the oceans to disappear, a process that happened on Venus.
In regards to past astronomical changes, Rachel, I'd recommend consulting with your university's astronomy department.
Not wearing my glasses, lol, I did a double take on the orbital precession diagram at ~10:30 to see if it really said "to vegas". Wouldn't that be something. Anyway, thanks for the video!
Thank you Jason black here your favorite fan
It is fascinating that the nanoplankton 016/018 ratios (from sediment coring during the mid-late 20th century) independently support the Milankovitch model (postulated in the early 20th).
I like to refer to this as science at its most elegant.
Love the science sharing! Thanks!
Sulfur and the ash. By the way, I have difficulty communicating because I had a stroke in Broca’s area, the part of the brain that controls speech. 2/8/2021 but I lived again. (My wife helped me compose this.)
What about water vapor which has more effect as a greenhouse gas.
12:35 Do you want to say that the formation of coal beds ("seams") form the carboniferous period does not line up with Milankovic cycles (theses cycles might have changed somewhat over the last 300 million years, but the basic principles should apply throuout the times). I've been under the impression that fluctuations in carbon burial, hydrocarbon depositions, seawater levels in past ice ages - apart from the global glaciation "snowball earth" events - were also an expression of the Milankovic cycles back then and that it is acutally mostly recurrent glaciation events that drive the formation of coal, oil and gas deposits.
Earth really just seems to go through a hard time everytime it plays matchmaker and these super continents just end up breaking up. I totally get that!
Hahaha Yes, the break ups really get to Earth
i’d rather think of the positive effects like the coming together of north and south america. although it was rough at first it worked out.
@meesalikeu it seems like earth had to experience a couple tough relationships with its continents coming together, but through all time positive lessons were learned, and you can see it in the life that thrived in those times
10:50 Sorry, I can't follow you on this line of reasoning - the connection of North and South America broke the "circumequatorial" (I am making this word up) ocean stream the stream of water from east to west around the equator and redirected that warm water as "gulf stream" to the North Pole. How would this lead to cooling of the Arctic Ocean?
Oceanography is my weak spot but my understanding is a current formed around NorthAm; not dissimilar from circumpolar current around Antarctica... but warm. The isthmus stopped it
Pretty CHILL Video 🙃
😂
Well done. Good summy as to when and how. Goes to my library.
Great work Geo Girl
Thanks!
Perhaps I can say regarding the astronomical causes that modern interpretation would be to consider how various cosmic variables could influence the Earth as it undergoes its processes, however I believe that the critical benefit of incorporating astronomical influences is from a Hermetic sense of, "as above, so below;" where the ways in which the Earth functions are closely compared to other known bodies in the cosmos. Pattern inference is crucial in scientific endeavors, and if we are stuck then it means we have exhausted the patterns that we have noticed that are most able to transform collective awareness.
One such pattern that looking to the cosmos can help reveal is that there is a spectrum of stable systems that form--stars, planets, atoms, black holes--and so we can consider the pattern itself and ask "is there any reason this pattern would end?" which, from a purely philosophical standpoint based in mathematics, there is no reason. Scientific consensus states otherwise, suggesting there to be an elementary particle of which all else is composed--once the atom, now subatomic particles. However, the existence of the inferred subtler and more massive still systems can help explain how observations such as magnetic fields and gravity emerge from a simple pattern, essentially of an infinite nature. As subtler systems are more abundant (there are more atoms in the universe than there are planets, for instance), mechanisms can be envisaged. Where gravity can be seen to be manifest from the motions of particles that would make photons look like black holes in comparison, that flow in all directions towards any given object and then when another system is near it blocks a portion of the flow of these particles and induces a relative low pressure on one side and causes attraction between the systems according to distance of separation and mass. And where particles can pass through other particles like neutrinos passing through the Earth, but be locked in a Figure-8 orbit in large abundance and cause fields (magnetic fields).
This though implies an infinite range of particles and so it is either infinitely complex, or they all behave the same but seen from a different angle of perception. There is no debate amongst humanity that we are all composed of the same constituents (atoms). Every other system in the spectrum of particles we see uses the atoms we are composed of to view it. But that does not mean all life is composed of what we call atoms. If there is an infinite spectrum of particles then it would be only reasonable that an observer could be composed of any of them--there would be no reason that the "atoms" of which we are composed are more "atom-like" than anything else in an infinite spectrum.
I say all this to say that, Earth is within this spectrum as well. It's mechanics are not separate and distinct from stars, but rather only seen from a different angles. For instance, the Earth has sunspots known as E.L.V.E.S. and solar flares that project through the E.L.V.E.S. known as sprites. It has a photosphere of the air glow of the ionosphere. It radiates light--in the infrared spectrum. It has the inner and outer Van Allen belts like the asteroid and Kuiper belts. It is a star. And stars can supernova, which is really a process of rapid change between two equilibriums for a system--like a reaction and like an excited electron, for instance. Venus is known to have undergone a planetary wide "supervolcano" event, resurfacing most of its surface.
Earth, too, can and has supernovaed. Seen from the angle of Earth, however, it is instead the transition that occurred when the Earth went from a single landmass where all continents were conjoined on a smaller radius globe to its present radius with newly formed ocean beds. It is a cornucopia of fundamental truths to the nature of reality stored in the immense detail of the Earth for us to study and apply multidisciplinary analysis of its truly awe-inspiring beauty and capacity to teach us what we as a society seek to know. It is even a molecule, able to reveal nuances of chemistry unfathomable otherwise.
It is in these ways in which the ice ages can be better understood. It is difficult to really elaborate on what benefit this approach could possibly provide to the topic, but without it there is no way to truly uncover what occurred. Earth supernovaed unequivocally, in my estimation, between the period of ~550Ma to ~12,000 years ago or of that magnitude. This caused rapid radioactive decay (a supernova is considered the decay of all the atoms of a star) while it went between two equilibriums (it is now largely stabilized), so what the actual time frame was is unclear. A supernova has a build-up "slow phase" and a rapid expansion phase--so did the Earth, with the rapid phase beginning when all the continents were so stressed from pressures upwelling below the crust that they spontaneously broke the remainder of what was necessary and internal pressures were able to stabilize as the ocean floors were largely formed during this phase, which occurred at the K/T Boundary.
Like a true radioactive decay process, it did not just do a single step but it went through several transitions, and based off the K/T boundary and its relationship to the ocean floor spreading (many anomalies such as the average age of ocean crust ~65Ma, hydrothermal vents changing at the K/T boundary in technical ways and other details) which indicate a tie between the extinction events and steps in the Earth's "supernova", then all extinctions would be steps in the decay process of the Earth. In all likelihood, these ice ages are tied to nuances of how such a process manifests, if we were able to "zoom in" on atoms and watch them react in more exact ways. The periodic table does not capture the depth of detail of the surface of an atom. We do not describe them as being as nuanced as the Earth, nor the Earth as simple as an atom, but if we view it as possible then it would mean the ice ages to be tied to the radiation released when an atom radioactively decays, almost like a built in stabilizing process for when something goes especially haywire in the system.
Pardon me I know I probably am very difficult to follow. However, these types of astronomical relationships I would suggest to be far more important than traditional considerations. :)
nice
My favorite phrase “I study . . . rocks.” Steven Stanley, one of the authors of Earth System History, wrote a book, Children of the Ice Age, in which he hypothesized that the rise of the Isthmus of Panama 3 Ma created the environmental conditions in Africa favorable to bipedal apes, Australopithecus, an eventually to us.
What about the iron-60 signal, produced from a supernova appr. 3 million years ago, which can be found in rocks from the ocean floor? Cosmic events as triggers for an ice age?
Wouldnt impact event also contribute to global cooling?
Yes, impacts can cause what are called 'impact winters' due to the dust that they throw up, but over the long term they tend to cause warming due to the relatively fast rain out of the dust and the longer termed lifetime of the CO2 in the atmosphere that get's released during impact. :)
Tree ring sequences in some parts of the world have gone beyond many times the lifespan of the local trees, by way of tree ring matching between trees that lived during various overlapping times.
Ice from glaciers in different parts of the world can be sometimes be matched from when individual volcanoes left behind some particular type of particulate deposit in the ice.
In theory, the same general technique might be usable by stromatologists (rock layer scientists) to match thicknesses of various rock layers in approximately the same shore region of a lake or sea. Shorelines move, especially if a change in lake or ocean level happens, but certain events can leave traces in the sediments that tell a story that a rock layer was laid down in approximately the same year. Also potentially occasionally helpful is that annual growth layers in a small fraction of stromatolites from hundreds of millions of years ago indicate that even then, the solar intensity cycle was close to the 10 2/3 year solar intensity cycle of modern times.
In order to find good evidence of a cycle of some sort, it is best to have a series stretching 3 or more times the cycle length. 32 years or longer is good for indicating an ancient 10 2/3 year solar intensity cycle for example, but is not good for indicating an ancient cycle lasting 20,000 or so years. It is very unlikely that annual layers lasting 60,000 or more consecutive years can be found in any one rock or in a series of age matched rocks to verify some ancient 20,000 year cycle, but that is the way such verification from the rock record would have to be done. Also, in ancient times, Earth rotated faster, and the Moon orbited closer, affecting how many thousands of years Earth's axis took to complete a cycle. If ever such a geological feat could be performed akin to the feat of matching annual tree rings, a hint would result regarding how close the Moon was at that time and how fast Earth rotated at that time.
One other hint in the rock regarding a roughly 20,000 year cycle would be a slight shift in the ITCZ during the Summer. If perihelion happens in January, Summer monsoon rains are less likely in the Northern Hemisphere for example than if perihelion happens in July, with a July perihelion resulting in more extreme Summer heating in the Northern Hemisphere that makes Summer monsoon rains more likely in the Northern Hemisphere. Of course, in order to count how many years there were in that type of cycle, 60,000 years of consecutive (or close enough to consecutive) annual layers are needed from the rock record, something that is unlikely to be found in rocks more than a million years old. Adding a little bit to the trickness of the time of year of perihelion is that the ellipse of Earth's orbit gradually rotates, as a result of Einstein's theory of relativity. It is not just the axis of Earth that rotates.
Here`s our main problem. The only reason our current civilization was able to form was a highly unusual period of climate stability (see ice/mud core data) that has no chance of continuing. We could be preparing for what`s coming but absolutely no effort is being made to do so besides some seed vaults. 4800 years ago there was the Burckle Crater impacts and mega tsunami plus a global downpour of rain, then the 536 A.D. catastrophe, the Hopewell Airburst, The Year Without A Summer and other events being discovered including massive solar outbursts 100,000 times more intense than the Carrington Event and heat and apparent blast damage to megalithic structures around the world. These things are deadly to modern humans in several ways. They will happen again. But we`re obsessing over a slight rise in temperature when the data reveals very rapid temperature changes in the past of up to 15 C (up or down) in under 100 years plus the info above. We`re all sitting ducks and nobody is talking about reality. This is all temporary.
@@baneverything5580 , disasters sometimes happen on a worldwide scale, and occasionally those disasters are separated by less than a decade. The first volcanic interruption of the military attempt by Belsarius to reunite the Roman Empire happened in the year 536 CE, a year that you mentioned as a year of natural disaster. Armies that have little food cannot march, but still have to be paid.
About 4 years later, another large volcano caused a second agricultural disaster in the Northern Hemisphere, in practice dooming the attempt to reunite the Roman Empire.
You are correct in asserting that the modern early 21st Century worldwide economy does not have sufficient just in case food inventory for a repeat of either one of those two Northern Hemisphere agricultural disasters that happened in the first half of the 6th Century CE, agricultural disasters that were both caused by volcanism. The longer lasting ancient civilizations understood the need for gradually building up food reserves sufficient for surviving one very bad harvest year happening in a 10 year time span.
The unfortunate current scheme of globalized economy in the early 21st Century does not make such a just in case food inventory scheme economically viable. Various lessons in government practice from the time of the ancient Roman Empire and the time of the ancient dynasties of Egypt have been unfortunately mostly forgotten. No longer exists anything remotely like the ancient government practice of setting aside some substantial fraction of the harvest from a good harvest year for future consumption after some bad harvest year that was almost inevitably going to eventually happen.
@@wendydelisse9778 Yes, there were two volcanic signatures in the ice core data several years apart...one at both poles. And there may have been space impacts too around this time. Diamond on Oppenheimer Ranch Project and Magnetic Reversal News had recent podcasts examining all the evidence and he was on Leak Project discussing it. Worth checking out. A huge volcano in El Salvador also erupted in 535-536 and a writer in Indonesia said an eruption "split Sumatra in half." The Chinese and Europeans reported massive booms. A huge volcano in Iceland and possibly even Alaska erupted as well and comet fragments may have exploded in the atmosphere. The evidence is very frightening.
@@wendydelisse9778 Hundreds died in Texas from a surprise power outage during a Winter storm. I started preparing days before here in Louisiana. Ice Storm = Power Outage. And we had one too. It got down to 2 degrees here but we had gas heat. Plus I have solar power that can run an electric blanket unless there`s no sun for three weeks.
@@wendydelisse9778 Imagine a worldwide freeze and power outage. Ice destroying trees and power lines and snow and ice caving in homes or burying them and the roads.
I would really like to understand why you seem to think carbon dioxide is a potent greenhouse gas, when its opaque to only an extremely narrow band in infrared, especially the broad band EM that water vapor blocks. Also, there's not much of it, compared to water vapor.
While water vapor has an overall much larger greenhouse effect than CO2, it remains relatively contstant with only minor fluctuations through time. Whereas, CO2 (in part because it is present at much lower concentrations than H2O) fluctuates much more drastically through time with changes in the burial v. emission cycle of C. Thus, these fluctuations cause temperature to fluctuate. We see these two parameters parallel each other time and time again on ancient Earth with independent reconstructions of both temperature and CO2 concentrations.
It's also important to remember that it is not the magnitude of CO2 in the atmosphere nor the magnitude of temperature change that makes climate change harmful to life, it is the rate at which the CO2 concentrations and/or temperature changes.
Thanks for the question, hope that helps! ;)
@@GEOGIRL I am of the opinion that extra CO2 in the air is actually very good for life, as there is direct evidence from satellite observations that plant life is growing better, especially in arid environments. Plants, being an autotroph, bring more food for the heterotrophs in most natural environments. More food, more life. I can find a source for that, but I think I gleaned that one from the IPCC AR5 or 6. Not sure, but it's hypothesized that plants are able to manage water more effectively with higher CO2 concentrations.
@@GEOGIRL furthermore... You did not address the relative strengths of H2O to CO2 absorption... Physically, CO2 is an ineffective infrared absorber and there is just not that much of it. The extra CO2 gas in our atmosphere can't make the troposphere any more opaque to infrared than it already is. Take a sheet of aluminum foil. That's opaque to visible light. Now add in a few atomically thin sheets of copper atoms. Is the aluminum-coper now MORE opaque? No... I think it's reasonable to say it this way, an infrared photon emitted by the ground gets absorbed by a greenhouse gas molecules. The odds are extremely in favor of being absorbed by H2O unless it wins an extreme lottery. Something like a billion to one. But alas, if the CO2 wasn't there, it would just get absorbed by the H2O molecule anyway.
I don't deny science, I am just really skeptical of this global warming alarmism that's going around... Ocean Acidification.
@@GEOGIRL besides... Couldn't the variability of CO2 be caused by ocean temperatures? Colder ocean, there's less CO2 in the air, warmer oceans, solubility of CO2 is lower... It's the CO2 follows temperature hypothesis, I have not heard much evidence against this idea.
@@kayakMike1000 Well, the hard thing to do with the 'temperature first' hypothesis is find the trigger? When we think about CO2 caused temperature change in Earth's history, it makes sense because an asteroid impact or a volcanic eruption burns a bunch of carbon deposits and releases it to the atmosphere as CO2, then temperature rises, we see this consistently in the rock record. Likewise, when period of major O2 increase occurred due to the evolution of photosynthesisers, we see that that major cooling periods happened as a direct result of the carbon uptake and burial by such organisms. Thus, atmospheric carbon increases and decreases can easily explain the temperature variations we see in Earth's history and we know what triggered these fluctuations, whereas, we do not know what would trigger a temperature variation if carbon fluctuation did not come first. There is of course possibiliies of astronomical effects that could cause temperature fluctuations, but these have been considered for all past climate change events and in most cases are shown to likely have only played a small role if that. I hope that makes sense ;)
thanks so much!!!! amazing! subscribed
Whoa I had no idea that we're currently in a Quaternary ice age. Although it's hard to tell since it's been so freaking warm these past few days. Anyway those ice ages you talked about sound intense.
The interglacial periods between the cool downs are considered part of the ice age.
There is a conjecture that the Ordovican glaciation (Andean-Saharan) might be related to the Ordovician Meteor Event which showered Earth with L chondrite meteorites that are prominent in the geological record of the Ordovician. The idea is that the parent body of L chondrite meteorites (an asteroid in the main belt) was destroyed in a collision 467 Mya, producing both the meteorites found in abundance then in Ordovician strata, and also (possibly) a cloud of dust which scattered sunlight and reduced the solar constant a little, contributing to the Ordovician glaciation.
The Ordovician Meteor Event is fairly probable, as we have the meteorite evidence and the L chondrite parent body has not been found in the asteroid belt. But the cloud of dust and its affect on Earth's climate is more of a conjecture, as there seem to be competing explanations such as non-vascular plant growth taking up CO2 and burying it.
I don't know whether there are proxies for atmospheric CO2 level that show CO2 decreasing before and during the Ordovician glaciation, but this conjecture would imply a cooling trend that was *not* caused by CO2 decrease, but instead by lowered solar flux at Earth -- so maybe it is possible to rule this idea out.
I confess, I forgot to close the freezer door.......It was late and I had to have a Cherry Popsicle and I just plain forgot to close the door.
I've been wondering if there's a connection between ice-ages and the cyclic nature of climate in the Sahara desert? It used to be full of lakes and savannahs, but they all dried up. Scientists project that in many thousands of years, it will be wet again. Is there any connection?
11:32 If I just could find someone to explain to me in a fashion comprehensible to a layman, why a change in earth's tilt affects average global temperature. After all, the surface area exposed to sunlight remains the same - so the amount of energy should remain the same on a global scale. It may change seasonally - but what you get less in wintertime, you get more in summertime, as the tilt increases. Same for the "wobble".
I hope that We will end this terrible ice age.
fyi i saw they just discovered 4 uranus moons have ocean layers and perhaps life - Ariel, Umbriel, Titania, and Oberon.
@Geo Girl you stated CO2 traps heat. Can you explain something for me? The Sun's radiation is converted into thermal (kinetic) energy in the atoms and molecules of the surface and in turn the surface cools by conduction and convection transferring thermal energy into the atmosphere. CO2 interacts with a small range of photons and converts their energy into thermal energy. This occurs within a few metres of the surface. If it did not convert radiation into thermal energy the temperature would not rise. My question is how do the laws of physics know to trap the contribution from CO2 whilst allowing all the thermal energy created directly by the Sun to escape to Space?
I am certainly not a physcist by any means ;) but it's my understanding that the CO2 contribution isn't fully or preferentially 'trapped' but rather that when the radiation from earth to space goes through the atmosphere, some of it escapes, while some interacts with and is scattered by CO2 (and other greenhouse) molecules in the atmosphere. This scattering of the thermal energy basically blocks its escape and keeps it in Earth's atmosphere for longer. There has always been CO2 in the atmosphere so this has always occurred, but with increased CO2 concentrations, there is an increased amount of IR radiation that hits these molecules on its way back to space, leading to increased thermal energy remaining in our atmosphere for longer periods at a time, aka warming. I hope that helps a bit, I know this doesn't fully answer your question from a physics point of view, but hopefully a physicist will comment on this thread to enlighten us! :)
@GEO GIRL A greenhouse demonstrates that very little radiation from the surface goes directly to Space. Experiments comparing two greenhouses, one with glass that blocks infra red and one with quartz glass that does not only show a small difference in temperature. The glass is blocking all the infra red whilst CO2 only interacts with a fraction. The physics of the Greenhouse effect relies on the majority of surface cooling due to radiation. If this was true, then the two Greenhouses would differ much more in temperature. If a surface cools mainly by radiation rather than conduction and convection, there would be no point in vacuum flasks. I think we are being misled on the issue of CO2.
@@wrath276 Well it's like you said the glass blocks it all and CO2 only interacts with a fraction. That still stands in the atmosphere. It is not that CO2 in the atmosphere either creates this effect or not, it is always blocking a small fraction of radiation from escaping, it is just that as CO2 concentrations increase, that fraction increases, and when it is a global phenomenon, the fraction of radiation blocked does not have to be significant for the overall global change in amount blocked to be significant during periods of increased or decreased greenhouse gases to the atmosphere. It is all relative not absolute. :)
@@GEOGIRL The key point you are missing is that the Greenhouse Effect is required to trap so much radiation that it raises the Earth's temperature from minus 18C to plus 18C. This just not feasible if only a small amount of surface energy is lost by radiation, the vast majority being transferred into thermal energy. You cannot trap radiation, it either escapes to Space or converts to thermal energy. What is important is the physics of how thermal energy in the upper troposphere is converted back to radiation so that it can be lost to Space. CO2 can operate in the reverse process by which photons are converted to thermal energy. If it is stimulated by the right amount of thermal energy it can emit a photon. So any increase in CO2 is self cancelling. I am still trying to find out how the vast amounts of thermal energy in Oxygen and Nitrogen the Sun creates daily is also converted to radiation. As an aside have you considered where all the free Oxygen in the atmosphere came from. Oxygen is highly reactive so it will not occur naturally. Life has spent 2.4 billion years separating the Carbon and Oxygen in CO2, the Carbon locked away in shells that become the white cliffs and coal created from ancient trees. There was only 0.028 percent CO2 left in the atmosphere by the 1900s Life was running out of fuel. When CO2 falls below 0.016 then most plant life cannot flourish. If CO2 traps heat it's hard to see how a planet with 70 percent of its early atmosphere as CO2 could evolve life as the oceans would have boiled away putting even more Greenhouse Gas into the atmosphere as Life had to start to enable the amount of CO2 to come down.
@@wrath276 I don't think anyone ever claimed that CO2 changed global temperature 36 degrees C. I think the most people argue that rising or falling Co2 causes is a few degrees C over decades if not centries/millenia. The thing that the greenhouse effect does do is trigger further warming or cooling, which is then exacerbated by positive feedbacks like decreases or increases in Earth's albedo, or methane hydrate melting feedbacks. The positive feedbacks are what lead to drastic temperature changes, but they wouldn't have been activated without the slight change in temperature caused by initial changes in CO2 concentration. :)
This is very interesting. I hather that the pleistocene icesheet protrusions in Europe (ie the weichselian and others) are not considered separate ice ages? Regards.
Astrophysicist here: I love you❤️
Thanks so much! ;D
Well done on the Phanerozoic! 😊👍🏻
Please don't get mad. A couple of things. Let's get the nitpick stuff first. Saying Huronian glaciation is technically incorrect. The Huronian is a lithostratigraphic supergroup. Not a time period. It would be like calling the Quaternary ice age the Wedron-Mason glaciation.
Now for the more technical. There is no solid evidence that the Huronian deposits were from a snowball earth. It's like every time we see glacial deposits in the Precambrian we leap to snowball earth. We have no solid evidence that the Paleoproterozoic glaciations were a snowball event. It's a complete assumption based of a bad Wikipedia article. The article wasn't even written by geologists. I tried to fix it but the damage is done.
The Huronian Supergroup consists of 4 groups and shows three main cycles of glaciation. The bottom group has zero glacial deposits. The direct and indirect glacial deposits only make up 11% of the supergroup and the deposits are no thicker than modern marine glacial deposits. There's no cap carbonates either. Most of the Huronian is passive margin deposits similar to the coastal plain deposits of today. Indicating warm climate.
We do have some paleomag data from that time. However it's 30-50 years old. So we don't even really know where the continents were located at the time. Everyone is so focused on Rodinia right now, that I don't see it happening any time soon.
I did a whole video on our misconception of the Huronian deposits about a year ago. I don't even know. LOL.
Oh that is so interesting, the things I read called it the Huronian glaciation, I guess they thought using the group for that one was easier considering the lack of well defined periods that long ago..? In any case, thanks for the clarification here! I'm gonna have to start watching your videos more often ;)
If anyone is interested in a super in depth video on the Huronian here's the link to one of Steven's videos on it! -> th-cam.com/video/bpIQhClkWcA/w-d-xo.html
@@GEOGIRL thank you! You do so much for geo education! I'm so glad you are doing so well here. If you ever need any Proterozoic stuff, I'm around.
everybody says Huronian glaciation
@@johnvoelker4345 like o said. It's technically incorrect. No they don't. Maybe on TH-cam. We all say Paleoproterozoic or Soderian because it was global. The Huronian is only in North America. Just because a lot of ppl say it doesn't make it correct. It violates the North American stratification code which is the standard we use.
If humans had continued to live like they did 10,000 years ago, how long would they have before glaciers started forming and moving south, again. 5,000? 10,000 years??
As we are, today, will we stop, or just delay the start of serious glaciation?
I don't know for sure, but I think I remember coming across something that if not for human-caused climate change, our inter-glacial warm period would probably be starting to close by now
We are past (in regards to Milankovitch cycles) peak insolation at the high latitudes so yes, without human interference there would be a sligh cooling at the high latitudes and possibly glacier building going on in the upper most regions of Canada.
We've not only assured that is not going to happen, but it looks like we're going to significantly melt the remaining glaciers in Greenland and Antarctica.
Hopefully, seen on a long run, the inevitable change from our present milder ice age state into a warmer one (presenting no permanent ice on the poles) comes smoth enough, so that we don't have to loose so much of all that magnificent biodiversity which makes our world so fascinating.
Does anybody have recommendations for books on the geologic time scale, any level of difficulty is okay with me.
I have a couple on my channel you might be interested in. They are all entry-level.
@@noeditbookreviews thank you. Will check them out.
Nice
We also really need to look at the times when the Earth suffered a supervolcano eruption (Level 8 or higher on the Volcanic Explosivity Index or VEI). The Toba eruption from around 73,000 years ago may have blocked out the Sun worldwide for over a year and may have triggered off an Ice Age that may have taken a couple of centuries to get the Earth back to normal, with a resulting small scale mass extinction event.
According to my father this is all because we left the lights on in the bathroom.
Or left the phone charger plugged in 😮
As I understand it, to account for the two-mile thick ice sheet and much lower world-coast lines of the last ice age, before the great melt-events (e.g., of Lake Missoula), you need the evaporation of roughly 320 meters of the (entire) world ocean. For this one requires a MASSIVE source of HEAT (e.g., a chunk of star from a super nova...something such...passing by). Needless to say, this is none of the five sources listed, and none (as far as I know) are commensurate with the heat/evaporation required.
Oxygen in the form of oezone is also a greenhouse gas as well as nitrous oxide
Hmm, what causes ice ages?
How about Dansgaard-Oeschger events causing Heinrich/Heinrich-Bond events?
Previous Dansgaard-Oeschger events have raised the global temperature 8°C (14°C?) in only 40 yrs (long, long ago).
Dansgaard-Oeschger events are followed by Heinrich/Heinrich-Bond events, which get very cold (ice ages).
Hey there again!
Hey! Glad to see you in the comments again ;D
@@GEOGIRL yeah, TH-cam quit recommending your vids. 🤷
If orbiting our sun causes so much climate change, does anyone know whether our 250M orbit cycle around SagA star has any effect on earths climate?
Atmospheric H2O is the dominant greenhouse gas, and all other greenhouse gases combined are minute compared to atmospheric H2O.
Animals that have exoskeletons or shells have "buried" more carbon than all other causes combined, especially those tiny animals of the oceans.
The planet warming causes increased atmospheric CO2, not the other way around, due to ocean off-gassing.
Well hello. You know what an iceage is. Instead of confusing glacial periords in an iceage as an iceage. Good for you. Just a pet peve of mine. 👍👍
Neglected to explain what an ice-age is. Via Wikipedia, An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers.
Earth's climate alternates between ice ages and greenhouse periods, during which periods there are no glaciers.
I am sorry I thought I said this at the beginning, but I should've been more clear. Thanks for clarifying the details here in the comments! ;)
To "do the Calculus" of creating prior states of NOW, from the be-cause-effect of e-Pi-i QM-TIME Completeness, in self-defining nodal-vibrational matrices of emitter-receiver log-antilog inclusion-exclusion, resonance timing-phases, vertically integrated harmonic/holographic positioning.., first principles reasoning process requires the idea that it is always NOW, and one has to prove it by moving positioning back and forth to differentiate between different states of time-timing sync-duration and distance, from clock timing rate of "temperature", to speed of travel ratio-rates, in a holistic Perspective, what you think you see is correspondence of Mathematical and "Musical" quantization-bonding, or reciprocation-recirculation of pure-math relative-timing ratio-rates "Circuitry".
Applications of this POV will require a literal shift of focus to work on complex issues like Ice Ages, but this was an excellent presentation to begin reiteration.
""I"m living in the Ice Age"".....Joy Division - "Ice Age"
The hypothesis that CO2 is a driver of climate is flawed.
It is rather a lagging indicator of global temps.
Simple example: Cold beer got lots of CO2 bubbles....warm beer don't.
During recent glacial/interglacial cycles it has been both. During Milankovitch-forced cooling, CO2 becomes increasingly sequestered in cooler ocean waters and in permafrost (the area of the latter, presumably, increases as the neararctic regions shift toward the equator).
At the end of a glacial period (again, initially due to Milankivitch forcing), CO2 is liberated back into the atmosphere, and (along with decreasing albedo) accelerates the warming trend (in a feedback loop), until a new equilibrium is established as an interglacial. The current understanding is that CO2 never exceeded ~270 ppm even during recent interglacials, but since the Industrial Revolution has increased to the present 400+.
@@anorthosite Greta Thunberg don't agree with Milankovitch!
@@sinkrock1 HUH ?
References/Context needed:
She's probably just calling out the folks who claim that "climate has always changed", failing to differentiate between past and present.
👍👍
The only reason our current civilization was able to form was a highly unusual period of climate stability (see ice/mud core data) that has no chance of continuing. We could be preparing for what`s coming but absolutely no effort is being made to do so besides some seed vaults. 4800 years ago there was the Burckle Crater impacts, then the 536 A.D. catastrophe, the Hopewell Airburst, The Year Without A Summer and other events being discovered including massive solar outbursts 100,000 times more intense than the Carrington Event and heat and apparent blast damage to megalithic structures around the world. These things are deadly to modern humans in several ways. They will happen again. But we`re obsessing over a slight rise in temperature when the data reveals very rapid temperature changes in the past of up to 15 C (up or down) in under 100 years plus the info above. We`re all sitting ducks and nobody is talking about reality. This is all temporary.
"Each period of 1200 years begins and ends with a catastrophe; human evolution expands and grows in the space of two scourges. Fire and water, the agents of all material mutations, work together during the same amount of time and each on an opposite region of the Earth."
We are on our way back down into a new glaciation period.
First requirement is land at high latitudes.
Like ... cold?
Ask Frasier Crane the question about predicting Earth's past orbits. If I remember, I'll ask the question and point to your channel. If he doesn't know he's got great friends.
What caused the end of the Carboniferous Period?
@grindupBaker LOL
Hello mam love from India ❤
3:25 "When tilt is smaller, poles receive less radiation, ..."
@grindupBaker Yes, more ice growth. But will the ice shield cover the poles or will there be an ice free zone directly at the poles? After all the closer you get to pole the longer your polar day gets (up to full year at 0° tilt).
@grindupBaker I thought I exactly said that in my initial comment.
@grindupBaker Don't mind. I like to be refuted (and in the end you still refuted someone!-)
Prepare for the ice Age 🐿
Um, we're already in an Ice Age dear! It's called the Quaternary. Are you talking about a glacial cycle? If so, the next one isn't predicted to start for another 50,000 years or so!
I think your ignoring the worm holes, stars positioning and major astronomical events in all of this....
Which country belong to mam,m
I am from the US ;)
I am Indian
Wow, we are so close to another ice age. I should buy that SUV to help save humanity.
One of these days your gunna come out of the agw closet 😆. Thanks for the video!
agw = anthropogenic global warming
Statistically, more CO2 has a high "positive correlation" with higher temperature during the last 280 million years on Earth. Mankind has apparently increased the sea level partial pressure of CO2 by about 30% in the 120 years that has passed since time that the automobile assembly line and the airplane were invented in the year 1903. Since 1903, the statistical correlation continues to be good between higher sea level partial pressure of CO2 and higher temperature.
@@wendydelisse9778 many scientists disagree
On an in between time scale of 66 million years, see "Atmospheric CO2 over the past 66 Million Years from Marine Archives", in the May 2021 edition of the Annual Review of Earth and Planetary Sciences. The authors seem to agree in the abstract portion of that paper that there is "coupling" between CO2 and climate during that time frame.
Back in the mid-1800s, Tyndall very publicly demonstrated the blocking effect of CO2 on infrared radiation, and numerous studies based on the geological record back up Tyndall's 19th Century findings. Angstrom also did some work in the very late 19th Century, with regard to the infrared blocking effects of CO2 and water at a temperature near the 100 degree Celsius boiling point of water. Angstrom's work might potentially have some bearing on the greenhouse effect of atmospheric water during the Haldean Eon.
Overall, the geological record agrees reasonably well with greenhouse effect theory. However, in the 1930s, Guy Callender noted that the greenhouse effect was progressing slightly faster than expected during the early part of the 20th Century. As such, historical record (and geological record as well) can be said to not be in full quantitative agreement with greenhouse theory, but are in excellent agreement from a qualitative point of view. Unfortunately, Callender's work still seems to be under copyright, and as such TH-cam channels are afraid of quoting from his paper.
Qualitatively, in a modern Earth-like atmosphere with a solar constant similar to that of modern Earth, more CO2 means more greenhouse effect.
@@brollyhessianovskov-ph1jc 98% of scientists disagree that many scientists qualified to have an opinion disagree.
@@davidrogers8030 that studys numbers been debunked. There are plenty or world class scientists in many subjects that don't agree with weather czars like al gore
we could map heavy objects with gravitational wave monitorring and invert time in a cmputer but you would need a lot of points of refrence at steeeeeeeller or at least planetery distances
What would happen if we drilled into Yellowstone ? .
I’m impressed by your study and rendition of accepted science. This video stands alone in a sea of “climate science” available on this platform.
However, some of your statements about CO2 in times past, while extracted from the literature on this subject, are suspect. Climatology is a field that has lost its way. The very oldest actual observations of atmospheric CO2 are 1.7 maybe… 2 million years old. These come from gas trapped in ice cores. And such ice cores are very very limited. Partially due to the scarcity of ice that deep and old, partly due to the limits of our ability to drill that deep.
So the information you provide about CO2 and it’s effect on atmosphere waaayyyy back is based upon proxy data and computer models. Not on actual observations. Now 30 years ago if I was to suggest that such model projects were weak, I would be crucified. In fact I was. Repeatedly. Today that is not the case. Time reveals all. And time shows that computer projects of 20-30 years ago are off. Way off. So far off that those dedicated to the proposition of global warming by CO2 remain strangely silent now.
The green house gases are moderators of what is a much larger physical process. Over the last 3 million years, some suspect 7 million but can’t prove it, we have been in this “ice age”. This is deceptive. In reality we have oscillated on a glaciation cycle with a period of 150,000 to 175,000 years per cycle. This cycle is defined by the Milankovitch cycles you allude to. Within each cycle is a glacial maximum followed by a glacial minimum. We are now in the minimum and still warming slowly. Statistically we have another 15-20,000 years before cooling again begins. Our observed weather data, compressed into climate data is consistent with this pattern based upon previous cycles seen in the ice cores.
Green house gases are simply not as effective as the majority contend. Put them back under the bed with the other childhood monsters and examine the facts. Sadly the facts are not widely available today. Science is based upon self evident observable facts. Not “proxy data” and general consensus. If it were not Galileo would have been burned for heresy and we would still live with the earth as the center of the universe. But that’s not the case.
So question your “facts” about the greenhouse gases. Do they work. Yes. We’d not be here without them. But they are the tail, not the dog. Don’t let them wag you so.
Over all a very good presentation.
Fox out
My actual PhD research is on refining our geochemical proxies for reconstructing Earth's history so I am well aware that everything presented here and in most of my videos is based on proxies :) But because that is my area of expertise I sometimes forget to make that clear to the viewer, and that is my bad. That is actually the reason why I mentioned in the pinned comment I would like to make a future video about how we reconstruct Earth's history (so basically a video all about how we use and refine proxies), which I hope will provide some much needed context for the rest of my Earth history videos :)
@@GEOGIRL
I see it now.
I also see I underestimated you. Flipping about, discovering a channel. A doctoral student no less. And me using a tooth brush that is probably older than you. Well I have subscribed. Let’s see where we go. Maybe I can keep up!
Fox out
I mean, who votes for the top 5 ice ages? This is not made clear.
Haha, sorry I should've made this more clear as well. These are just the most widespread ice ages throgh Earth's history based on the current knowledge of the rock record. However, this list can change over time with new pieces of evidence for these and other events. :)