Interesting: "Towards the base, the ice is more than 120,000 years old and dates back to the last interglacial period, a time when the atmospheric temperature above Greenland was 5°C warmer than today."
It also shows how crazy it would be if we get the projected 2-3 degrees average temperature increase. Even in a period where we'd expect to be going into a new ice age; instead shooting to a previously unseen high temperature.
On the other hand if we only have 2-3 degrees of warming, if that’s enough to prevent the next ice age, didn’t we just dodge a massive icy bullet? Might we not one day thank ourselves for doing something reckless and stupid that actually worked out?
Yeah a warmer climate brings all kinds of horrible changes. But food still grows in the northern hemisphere. A colder climate is arguably even worse for us.
By the way, that’s no excuse to keep doing what we’re doing. Limiting warning at 2-3 degrees will be nice. Things get really horrific above 4. At some unknown point feedback cycles really kick in and we go to 5-10 degrees and get completely fucked. We really have to not find out where that threshold is.
There's no bullet to dodge. Minus human intervention, the next ice age would be in 50,000 years. Humanity will be either some unrecognizable scifi trope or, more likely, long gone by then. Planning for it is pointless.
The time scales for anthropogenic climate change and the previous temperature cycles are so different as to not be comparable.
> Minus human intervention, the next ice age would be in 50,000 years. Humanity will be either some unrecognizable scifi trope or, more likely, long gone by then.
I think you are overestimating the probability that humanity would be "long gone by then". Even if a series of catastrophic events + climate change make life as we know it (modern civilization, globalized society/trade) untenable, humans are smart and many places on earth are reasonably forgiving to survival. Not saying it would be comfortable tho.
I’m just saying that a silver lining of the mess we’ve made is that we probably won’t have that ice age in 50,000 years. We’ve likely disrupted the cycle.
It’s mostly caused by Milankovitch cycles. Which are cyclic variations in our orbit around the sun.
The earth varies in distance to the sun and axial tilt and precession. Like waves, there factors can either overlap and somewhat cancel or they can stack for a larger effect.
ice ages didn't happen until after the asteroid strike. Antarctica moving into the south pole is likely a large part of it, but they don't really understand ice ages that well TBO. Anyhoo, the Earth was a lot warmer prior to the strike and we have been going through extinction events every 100k years.
By "the" asteroid strike I'm guessing you mean the one 66M years ago? There were definitely ice ages before that, likely including one or more Snowball Earth phases (the whole surface frozen): https://en.wikipedia.org/wiki/Snowball_Earth.
What I gathered is that if the gulf stream stops, warm water will no longer flow north and the ice sheets will grow explosively, triggering an ice age (the kind where thick ice sheets flow southwards). That would pretty much wipe out anything built in the northern half of Europe... although granted, I don't know if it was like a kilometer high ice sheet rolling our way or how fast it went in previous ice ages, it might be slow enough that it can be stopped and broken down before it causes damage.
This is 99% conjecture. The current climate models do not predict those kinds of changes and most don’t have the fidelity to do so. Even the best models can’t account for simple things like aerosol pollution and they don’t have the resolution to determine the behaviour of ocean or atmospheric currents.
Early onset of glaciation via warming instead of cooling. Counter intuitive idea.
It’s unclear that it would play out that way. One could look at what happened the last time it stopped to get some idea, but things are different this time. We have a lot more atmospheric CO2.
* 170,000 years ago: humans are wearing clothing by this date.
* 125,000 years ago: the peak of the Eemian interglacial period.
* ~120,000 years ago: possibly the earliest evidence of use of symbols etched onto bone
* 75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people
The Eemian climate is believed to have been warmer than the current Holocene. Changes in the Earth's orbital parameters from today (greater obliquity and eccentricity, and perihelion), known as Milankovitch cycles, probably led to greater seasonal temperature variations in the Northern Hemisphere. During the northern summer, temperatures in the Arctic region were about 2-4 °C higher than in 2011.
The hippopotamus was distributed as far north as the rivers Rhine and Thames. . . . The prairie-forest boundary in the Great Plains of the United States lay further west near Lubbock, Texas, whereas the current boundary is near Dallas. . . . Sea level at peak was probably 6 to 9 metres (20 to 30 feet) higher than today . . . .
There is definite evidence of hominins in North America 130,000 years ago (search "Cerutti mastodon"). Nobody knows if they were H. erectus, Neanderthal, Denisovan, modern humans, or "other", but with an interglacial at 125,000 years ago, it is not hard to see how they could have got here.
Wikipedia over-represents the opinions of retired professors. As Max Planck wrote, "Science advances one funeral at a time".
The usual shallow, reflexive objection is that the bones must have been broken and carefully re-arranged via being run over by construction equipment. This absurd suggestion has been very thoroughly demolished without assistance from construction equipment. It is hard for dump truck tires to produce green-stick fractures in 130,000-year-old bone, or to put bone fragments into the pores of stones and then move them yards away, all while underground.
This raises a very critical point. Nuclear is the only dependable energy source. Fossil fuels will run out or go out of favor. Solar and wind on the other hand will become victims of the next major volcanic eruption as ash destroys them or renders them ineffective.
Deep drilling based geothermal can fill this role too though - and does have the substantial benefit over nuclear that it leaves no surface-supply chains for resources (uranium).
Given that we're so close to being able to do it, we honestly need a Manhattan project initiative to push it through to reality (with the outcome being the machine and process to do the drilling).
An eruption significant enough to impact solar and wind generation globally will also affect other critical requirements of humanity, and the Earth's ecosystem, globally.
Which is to say: You Will Be Having Bigger Problems.
Recovery from regional meterological catastrophes is well within human capabilities.
Nuclear facilities seem pretty fragile / demanding, I doubt one would survive any kind of apocalyptic event. The infrastructure supporting it will be gone.
Nuclear facilities can probably continue to operate amid persistent cloud cover and ash. Wind turbines and solar can not. Agriculture would have to shift artificially lit greenhouses.
Though as a corollary, such an event would be civilisation-ending in any regard.
It's also ... highly rare. Somewhere in the 1 in a million to 100 million year range, which is to say, not only longer than the planning horizon of most human institutions, but well outside the existence of the human species for the most part.
It's also well beyond the available supply of terrestrially-minable uranium,[1] and possibly of ocean-extracted uranium,[2] and thorium[3]. Breeders might be another option, though I've seen no substantive estimates of total fuel availability for that case either.[4]
But as an argument favouring nuclear over other energy options ... this is pretty silly, really.
About the only viable defence against such a risk would be, and I say this as someone who's markedly pessimistic on space colonisation, independent and self-sufficient habitations off-Earth: YACP.[5]
________________________________
Notes:
1. If we relied on naturally-occurring terrestrially-mined uranium for all present human energy consumption ... supplies would last fewer than two decades. This is seldom mentioned by nuclear advocates.
2. This offers a potentially much larger supply, as uranium is present as a solute in seawater, but viable industrial-scale extraction is unproven and would require filtering vast quantities of seawater.
3. Thorium is reasonably abundant, though I'm not quite sure how abundant. Thorium-based reactors are not much used, and the concept of molten-salt reactors (MSR) which gained some popularity in the past decade ... faces some very significant engineering hurdles. Managing high-temperature highly-corrosive radioactive salts is ... challenging.
4. Breeders produce plutonium. And now you have two, or more, problems.
"75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people."
The key question is: How much CO2 did that super-eruption emit into the atmosphere?
In our hurry to attribute climate change to our meager impact on this planet, we tend to forget what horrors an eruption of this magnitude can cause. And who knows how many of them happened during the past millennia.
Water vapour is consistently the most abundant volcanic gas, normally comprising more than 60% of total emissions. Carbon dioxide typically accounts for 10 to 40% of emissions.
Citing: H. Sigurdsson et al. (2000) Encyclopedia of Volcanoes, San Diego, Academic Press.
(Late edit: though I note that this seems to discuss percentages of gaseous emissions, not total ejecta. Anyone have a better source here?)
One of the largest volcanic events I'm aware of is the Siberian Traps eruption, about 250 mya, with a volume of about 4 million km^3, another three orders of magnitude greater than Tomba.
This has been linked to the Permian–Triassic mass extinction event, with the mechanism being release of methane clathrates and/or stimulating growth of a microbe which released vast quantities of methane into the atmosphere, killing ~81% of all extant marine species and 70% of terrestrial vertebrate species.
"The level of atmospheric carbon dioxide rose from around 400 ppm to 2,500 ppm with approximately 3,900 to 12,000 gigatonnes of carbon being added to the ocean-atmosphere system during this period."
-- Wikipedia, citing Wu, Yuyang; Chu, Daoliang; Tong, Jinnan; Song, Haijun; Dal Corso, Jacopo; Wignall, Paul B.; Song, Huyue; Du, Yong; Cui, Ying (9 April 2021). "Six-fold increase of atmospheric pCO2 during the Permian–Triassic mass extinction". Nature Communications. 12 (1): 2137. Bibcode:2021NatCo..12.2137W. doi:10.1038/s41467-021-22298-7.
Yeah, it's the comparison between DRE and Gas ejecta that got me bogged down before.
Having now given up, I asked ChatG4. It says "the mass ratio between DRE and gaseous emissions might be on the order of 20:1 to 100:1", no citations ofc.
So, just as a strawman and using your 10-40%, on the low end .01.1 = 0.001, high end .05.4 = 0.02. So .1%-2% of ejecta by mass is CO2 emissions. Hah :)
Using my orig figure for Toba of a billion gigatons of ejecta, of which roughly a million gigatons would be CO2. Correct math?
> And who knows how many of them happened during the past millennia.
We at least have a significantly large list of what we know [1] - that's part of the purpose of core drilling, the ash deposits worldwide can be linked together to estimate where ash traveled to. Also, craters and their surrounding can be drilled into to determine eruption events.
Not even close to what we as humans emit. The rate of the global annual natural CO2 emissions are 1-2 orders of magnitude slower than anthropogenic emissions.
Considering the rapid rise in temperature on a relatively miniscule geological timescale, I'd be more interested to see evidence that it's not a manmade phenomenon.
Iirc, the CO2 concentration now as been pumped up higher than it was then, which is in part what is worrying because temps might then potentially shoot even higher.
Bottom line: we need large scale carbon capture quickly because even if we reach net zero CO2 will take millenia to drop back to the level it was pre-industrial revolution.
Edit: I wouldn't focus on "pre-industrial levels" specifically, the point is that there is too much now so we most likely want concentration to drop as soon as possible.
One of the many misleading things done by climate scientists is to splice together data derived via different measurement methods.
The CO2 curve 800000 years back is an excellent example.
CO2 in air bubbles in ice will diffuse into the ice during the many millenia the ice have been stored under pressure. You can therefore expect the ice core CO2 to be lower than hypothetical atmospheric measurements at the same time.
The diffusion is expected to progress fastest at the start, and then more slowly.
Still the artifact is absolutely obvious as the CO2 concentration peaks are lower
and lower the further back in time it goes.
Yet of course someone had to splice it all together and not even add error bars.
Not sure if you are trolling of really believe this to be true, but for anyone else assuming good faith: The diffusion aspect is (of course) well-modeled, see e.g. references under "past greenhouse gasses" at [0].
They have found some meltwater layers with unexpectedly large quantities of CO2 > 750ppm.
But they also show that there is unexpected heavy diffusion around the meltwater layers. And they argue very compellingly, that the ice core CO2 records have been smoothed through natural diffusion.
Why is this information not given when showing this graph?
Where is it well-modelled? Noble gasses will diffuse differently from CO2. And on-top of diffusion of course CO2 will make hydrogen bonds with water in the ice.
It is well-understood that many ice cores give the same relative shape of peaks of various gasses through time.
Going from there to claiming knowing the absolue concentrations without very large error bars, is just not science.
"Carbon dioxide measurements from older ice in Greenland is less reliable, as meltwater layers have elevated carbon dioxide (CO2 is highly soluble in water)."
I do wonder if some of the "massed solar sail" ideas for terraforming Mars' atmosphere would work here (in short: use cellphone processors to build and launch a couple hundred thousand solar-sail equipped satellites).
Because it would be expensive, but it would kill several birds with one stone: we (1) prove whether the concept would work on Mars, (2) develop the technology to do it, and (3) unlike SO2 in the atmosphere, "switching it off" or modifying the scale of the effect can be done almost instantly (you could remove the swarm by having it fall back to an Earth orbit).
Is there anything left to really "figure out" about carbon capture? The tech works, it's just too expensive. Given a sufficient amount of cheap enough energy it could be scaled up as far as I understand.
As a layperson, it's just one more reason I so wish we'd invest in nuclear. Nuclear powered DAC plants might be the only way to scale it fast enough. Sure, it would still be expensive, but that's much cheaper than not massively reducing CO2 in the atmosphere.
Based on our record of environmental interventions; SO2 sounds suicidal. But it only lasts a few days in the atmosphere so maybe it has an in built off switch.
Note that is for the stratosphere, not the atmosphere.
The mechanism is well known from volcanic eruptions, and it only lasts (from memory) 1-2 years in the stratosphere, so if something goes wrong, it can easily be tapered off.
We have also pumped a very large amount of long-lived fluorine compounds into the air, that will last for centuries. They have from 2500x to 25000x times the "greenhouse gas warming potential", kg for kg. They are mostly refrigerants (CFCs, HFCs, and soon their successors) and transformer insulation gas (SF6). Volcanoes do emit some amount of fluorine compounds, too.
We also have a great deal of methane leakage, which is usually cited as 25-100x, and we may soon have a lot of hydrogen leakage, at >100x. Rocket launches are installing water vapor, another one, into the stratosphere like never before.
So even if we got CO2 down to a pre-industrial level, we would still have heat forcing from the fluorine- and other compounds.
Capturing CO2 is kind of pointless until we get emissions under control. I.e., a dollar spent preventing emissions buys much more than a dollar spent capturing. Solar panels and wind turbines directly displace mass emitters of CO2.
I don't know about all compounds but CFCs stay in atmosphere for about a century only and we've already banned them, and methane has a very short lifetime of about 12 years. So we 'only' need to control emissions of those to solve the problem.
On the other hand, as said, CO2 stays for centuries if not 1,000+ years so at this point net zero is only half the job though probably the hardest part.
Yes and: I understand that we want to prevent the non-human emissions from becoming a positive feedback loop. Meaning that at some tipping point, the thawing tundra, burning forests, and acidic oceans will continue to get worse, even if/when human emissions completely stop.
Pre-industrial CO2 concentration is synonymous with the "natural concentration", at least in the recent past. We made a very large change that has thrown Earth's systems out of equilibrium. Returning to pre-industrial CO2 levels would undo that change and bring things back towards equilibrium.
“Natural concentration” is not the right way to look at it because there are higher concentrations that predate the industrial revolution and humans. The all time high (that we know of) is from about 350,000 years ago. This was by all means natural and pre industrial revolution.
"The only known natural concentration empirically compatible with long-term human civilisation".
"The planet did exist/will exist just fine without us" is a pretty worn truism. You might as well wryly note that water isn't natural because everything was hydrogen once.
> empirically compatible with long-term human civilisation
Empirically observed, atmospheric CO2 went from ~320ppm to ~410ppm from 1970 to 2020[0], during which period the human population more than doubled from ~3.7B to ~7.8B and yet deaths caused by climate dropped threefold[1] (not 1/3 the rate; 1/3 in absolute number).
They are dynamical systems, there is no equilibrium. See also: climate charts for the last few ice age cycles.[1] In the bigger picture we want to modify Earth's climate and definitely do not want to end the current interglacial period, to be fair we've already done that, but returning to a "natural" pre-human climate cycle on the 10,000 year scale is not desirable.
Dynamical systems can have equilibrium points —- e.g. an inverted pendulum is stable when hanging straight down. If you deviate too far from an equilibrium point, the system may find another equilibrium that is less desirable for the user. I’m not an expert in climate change, but those things certainly happen for engines, robots, and other systems.
I like to think of it as scrappy terraforming because we aren't even sure we could handle any of the naturally occurring variation.
Scrappy because, well the planet doesn't quite become uninhabitable and we're starting from the end-game. Science fiction also had me expecting some very cool terraforming infrastructure, not psy-ops to get the serfs to eat bugs.
The point is that net zero is most likely not going to stop warming with 400+ppm CO2 in the atmosphere. CO2 concentration most likely has to drop but naturally it does so very slowly. Arguably at this point we already need cooling because 40+C every summer in half of Europe (for instance) is getting annoying...
Yeah it would be pretty silly for humanity to invest so much time and effort into lowering CO2 levels only for a Yellowstone or equivalent to erupt and send temperatures plummeting into a new ice age levels. When if humanity did nothing the eruption would only have taken us back to pre-industrial age temperatures.
That is the point where we started adding greenhouse gases that lock in energy from the sun, we need to at least get back to those levels to start releasing some of the heat. Otherwise we're containing to add insulation to an oven that already overheating - you'd ideally want to take off all the insulation and the metal casing since you can't turn off the heat, but the casing isn't an option so we need to remove the insulation and hope it hasn't gotten too bad yet
I think people who are not already familiar with the known history of the Earth find it interesting that there have been higher CO2 levels and temps than there are now.
And I agree: the history of the Earth is interesting. Which is why so many people study and work in the field of geology.
It's interesting because the whole ice cap as we know it is around 120k years ago which I don't consider the long ago on human development scale. This also appears to mean that in the past 120K there wasn't a polar ice cap. I read that as the worst case scenario we should be using for long term planning. This also may help determine how fast the ice was built and how fast it will melt.
This will also assuredly fuel some interesting ideas about the origin of the Piri Reis map. A 120k year old ice sheet could mean that humans once lived on Antarctica.
It does make one wonder if any ancient sea fearing humans happened to carve a world map into a durable material such as granite which could have survived until the modern historic era. Maybe such a map, or other mythological artifact fueld the Roman idea of Terra Australis Incognita
The Polynesians used stick maps to identify currents and land masses relative positions.
With no evidence I believe navigation cues were built into the vessel. By keeping celestial bodies aligned with marks on the vessel one can achieve a seasonal calendar as well as documentation on how to modify the configuration for the next leg of the journey.
IIRC the 'maps' made of organic materials were very much a rarity slash teaching aid for the later incarnations of traditional navigation cultures of the Pacific which we have surviving material on. Mostly they used mental maps, and of course the most sensitive instruments available at the time ... at least one example of which was hanging their balls off the edge of the canoe to see if they could detect a temperature shift. A good book on the subject is We: The Navigators though it draws only from one area.
Source: Have a Pacific art collection, have been to most of the major museums on the subject, interested in sailing, authored some of the Wikipedia (featured) articles on related watercraft.
Maybe humans become more developed because it got colder? Even on a country and global scale, the south is usually "behind" the north. It's hot, no one wants to do anything.
The American south (Arizona, Florida) were tiny and unimportant until air conditioning entered the chat. Phoenix was at 100 thousand people in the fifties.
The cold makes us think, the cold make us survive, keeps us on the edge - where we need to be. Respek the cold!
All of the world's "great" civilizations come from places with strong seasonality. The ones that didn't have winters had flooding seasons and dry seasons. Some of them had both. It also doesn't need to be bitterly cold for winter to have an effect on crops.
Sumeria and Egypt both had seasonal flooding. Italy and Greece have winters that are cold enough to disrupt agriculture. The Aztecs and Mayans had seasonal floods. The ancient Chinese empires had both. Japan has winters. The list goes on.
On the other hand there’s something to be said for a comfortable climate that leaves people with time to think when the everyday isn’t a constant complex struggle.
The Inuits of Greenland and Sami people of Lapland didn’t have Aristotle or Confucius.
Maybe there's a "sweet spot". Too warm and not enough seasonality leads cultures to not be that productive, but too cold and daily life is just too much of a struggle to invent calculus. Greenland and Lapland are probably too far north to have decent agriculture, and never had large enough populations to develop much civilization. Cultures that had people like Aristotle or Confucius had very large populations for the time.
That we know of; did they have a system of writing?
I find it hard to believe they wouldn't philosophise at all. Confucius got famous (like sun tzu et al) because his ideas were written down, published and spread.
The number of different words they have for snow and ice demonstrates a cultural understand of distinct attributes of objects. I think this would be the first step of consciousness understand one thing as distinct and separate from another.
That is only due to writing. I always felt that the high latitude civilizations led to technological development due to the high risk and high solitude.
I find it interesting because it raises questions that I don't have answers to. For example:
- What caused the temperature above Greenland to be 5°C warmer than today? Why is it cooler now compared to 120,000 years ago? What causes the interglacial periods? Is glaciation the more common state of the climate?
- The article says the ice sheet is melting at the bottom? Why? Pressure from above? Friction from movement? Heat from the Earth? Something else?
- Was the ice sheet shrinking or growing when the temperatures above Greenland were 5°C warmer than now? Does existence of the ice sheet imply that 5°C warmer for some period of time is not enough to melt the Greenland ice sheet?
- How much climate data has been lost to melting from the bottom? Is the ice sheet thickening or thinning compared 120,000 years ago? How would we know?
- How much has the Greenland land mass moved in 120,000 years due to plate tectonics? Could this have impacted the ice sheet in this short amount of time?
- Humans adapt. How did humans adapt to a climate that was warmer by up to 5°C 120,000 years ago?
- How long did the warm temperatures persist 120,000 years ago? 10,000 years? 50,000 years? Or more?
- Could a cooling climate be more worrisome to humanity than a warming one?
the drilling allows sampling of environmental components over extended period of time. this meas a historic record of, gases, ash, soot, pollen, spores, silt, insects, plant animals, metals, salts.....
It's not scientifically interesting, the glacial-interglacial cycles are pretty well established. I'm guessing they're trying to insinuate some climate change minimalism argument.
It also shows how crazy it would be if we get the projected 2-3 degrees average temperature increase. Even in a period where we'd expect to be going into a new ice age; instead shooting to a previously unseen high temperature.