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Ch. 3: A brief history of ice on planet Earth 
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 Ch. 3: A brief history of ice on planet Earth
A Farewell to Ice: A Report from the Arctic
by Peter Wadhams


Please use this thread to discuss Ch. 3: A brief history of ice on planet Earth.



Tue Jun 16, 2020 6:41 pm
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Post Re: Ch. 3: A brief history of ice on planet Earth
Chapter Three: A Brief History of Ice on Planet Earth

This chapter provides a superb contextualisation of human history within the deep time horizon provided by geology, over the 4.54 billion years since our planet condensed out of the solar nebula. Earth had no ice at all for several billion years. The surface was at first molten, with almost no oxygen in the atmosphere. Life started up after half a billion years or so, and then photosynthesis began about two billion years ago, gradually starting to inject oxygen into the air.

One big icy setback was the first known snowball earth, when the temperature of the whole planet fell below freezing and ice covered all the oceans up to a kilometre deep. (Not sure if these glaciers also covered all the land or if some mountains poked through). The Huronian glaciation lasted for a hundred million years until 2.3 billion BC, but somehow microbial life survived this harsh period. The sun was 15% dimmer than today. It seems that a slowing of volcanic activity reduced the greenhouse effect, expanding glaciation until the white surface reflected 80% of the sunlight back to space, generating a completely white planet until volcanoes broke up the ice by sending up warming clouds of methane and CO2.

The next snowball earth period was 710 million years ago, when all the continents came together to form the single super-continent Pangaea, near the equator, which somehow caused silicate weathering that removed so much CO2 from the air that the planet froze again. The last snowball was 635 million years ago, lasting about ten million years, possibly caused by a cloud of space debris blocking the sun. But the primitive algae survived all this and kept on pumping oxygen into the air, which eventually reached a threshold in 580 MBC whereby single living cells could combine, producing the Cambrian Explosion.

The relevance for current iciness is the speed in the geological record of changes in CO2 level. We now add about three parts per million of CO2 to the air each year. The fastest geological rate of CO2 increase looks to be about 0.2 ppm after the asteroid wiped out the dinosaurs in 65 MBC. That caused major heating, but nothing compared to what we are now doing.

For the last 50 million years, ocean sediments show the temperature gradually fell until the ice age temperature oscillations started about 6 million years ago. The interesting thing is that the natural temperature reached a point whereby tiny oscillations of our orbit – the roundness, tilt and wobble – were enough to trigger advance and retreat of glaciers. Previously these orbital factors were swamped by terrestrial effects. The orbital change in incoming sunlight against the seasons was enough to create accelerating feedback loops. CO2 and temperature gradually fell for a hundred thousand years, until suddenly bouncing back to their previous level. So we see the sawtooth graph of CO2 over the last million years producing repeat ice ages until humans came along and stopped them.

Ruddiman argues that the rise of agriculture in the Neolithic period about ten thousand years ago released so much methane from rice and cows that it disrupted the natural process which would have already had the planet fall back into a new ice age. The situation now is that the great climate disruption we have created with fossil fuels dwarfs anything agriculture could cause, sending us on an iceless hothouse trajectory. The last time the planet had the current CO2 level the sea was about 20 metres higher, so that is the equilibrium that will arise unless we work out a technological fix for climate change.


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Post Re: Ch. 3: A brief history of ice on planet Earth
Thanks for this summary. I confess myself a bit astounded that the earth's climate had reached such extremes (well, I have seen dioramas of the dinosaurs slogging around in a really warm climate, but "covered with ice" seems more dramatically different). The science put on display is impressive.

Should we take seriously this idea that we "would have been" in another ice age? It is interesting, but I don't have enough background to evaluate Ruddiman's claim. I do know that a fair amount of the smokescreen put out by climate denialists emphasizes former fluctuations, but my response when I run into that is the "fingerprints" of anthropogenesis.



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Post Re: Ch. 3: A brief history of ice on planet Earth
Harry Marks wrote:
Thanks for this summary. I confess myself a bit astounded that the earth's climate had reached such extremes (well, I have seen dioramas of the dinosaurs slogging around in a really warm climate, but "covered with ice" seems more dramatically different). The science put on display is impressive.
In astronomical terms, the temperature band of liquid water against the range from zero to hot stars is rather like the band of visible light against the electromagnetic spectrum – tiny. Richard Dawkins compares the visible light band to the eyeslit of a niqab.

So the fact that our planet has never steamed off like Venus is fortuitous. That is the parable that James Hansen describes in Storms of my Grandchildren. Luckily, freezing to the point where the oceans are all covered by a kilometre thick layer of ice was something our microbial ancestors could bounce back from. Staying in the Goldilocks Zone is just part of the amazing complex set of circumstances that have enabled the incredible durability of complex life in an incredibly harsh and unforgiving universe. This means of course that we should be far more attuned to how incredibly fragile and sensitive our existence is to seemingly tiny changes in our planetary environment, when considered over timeframes longer than an election cycle.
Harry Marks wrote:
Should we take seriously this idea that we "would have been" in another ice age? It is interesting, but I don't have enough background to evaluate Ruddiman's claim.
Yes indeed, Ruddiman’s argument is compelling. The last ten, or perhaps thirty, glacial cycles followed the same descent into the maelstrom of ice every hundred thousand years. Civilization is the anomaly. Neolithic temperature and therefore sea level held up for far longer than in previous cycles, considered against the orbital dynamics.

The only material difference is that agriculture had injected such a large quantity of GHGs into the air that the natural cooling cycle was prevented. So as Wadhams explains in the next chapter, we have now moved out of the orbital driven cycle of climate and are into an Anthropocene where our decisions will determine the sea level, temperature, biodiversity, acidification, ice and snow cover, and basically set the conditions for everything in planetary biological and climate systems.
Harry Marks wrote:
I do know that a fair amount of the smokescreen put out by climate denialists emphasizes former fluctuations, but my response when I run into that is the "fingerprints" of anthropogenesis.
Climate denialists have the moral and scientific authority of Holocaust denialists and flat earthers. Everything they say involves the evil fallacy of a predetermined conclusion (don’t worry about global warming) in search of rationalisations which always turn out to be spurious. Denialists have managed to poison the well about analysis of past climate in terms of popular culture with their bizarre assertions such as that solar fluctuations explain current climate change. Wadhams has nothing but contempt for such corrupt deflection from science. As you suggest, the ‘fingerprints’ of human causation of climate change are all over the unprecedented long climate stability of the Holocene. This is a stability that we can only sustain through geoengineering.


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Post Re: Ch. 3: A brief history of ice on planet Earth
Robert Tulip wrote:
Ruddiman argues that the rise of agriculture in the Neolithic period about ten thousand years ago released so much methane from rice and cows that it disrupted the natural process which would have already had the planet fall back into a new ice age. The situation now is that the great climate disruption we have created with fossil fuels dwarfs anything agriculture could cause, sending us on an iceless hothouse trajectory. The last time the planet had the current CO2 level the sea was about 20 metres higher, so that is the equilibrium that will arise unless we work out a technological fix for climate change.

We don't see the really sharp rise in CO2 beginning until about 1850, so I don't understand how our burning of wood and releasing methane through agriculture could have forestalled another ice age by itself. Isn't the threat all about the release of highly concentrated carbon that began only when we
started mining coal? Not only does our current release of carbon dwarf what agriculture caused, but Wadhams tells us that events like the meteor that hit the Yucatan, eliminated the dinosaurs, and eventually produced a rise of CO2 to 2,000 ppm are less potent contributors as well. I confess I have a hard time getting my mind around that, which may be broadly indicative of the stubborn inability of our minds to comprehend how billions tiny inputs have done what catastrophes could not. The key I suppose is that catastrophes in retrospect may seem to have been sudden, but their effects were actually spread out over a much longer period of time than the relative eye-blink of our fossil-fuel economy. The annual rate of rise is greater in our era.



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Post Re: Ch. 3: A brief history of ice on planet Earth
DWill wrote:
We don't see the really sharp rise in CO2 beginning until about 1850, so I don't understand how our burning of wood and releasing methane through agriculture could have forestalled another ice age by itself. Isn't the threat all about the release of highly concentrated carbon that began only when we started mining coal?
The point here is to understand just how sensitive our planetary climate is to tiny effects, when those effects create a sustained small forcing in one direction for a long time. Before the transition from the stone age, invisible orbital and tectonic changes were enough to cause ice ages to start and end, operating on time scales of thousands and millions of years. Then, with the emergence of agriculture, the increase of atmospheric methane, although tiny by modern comparison, was still enough to counterbalance the radiative forcing of the orbital shift that in previous cycles had plunged the planet back into a new ice age. So what we are doing now is a complete recipe for catastrophe over any timescales longer than political elections, but the electoral cycle is the only timescale that matters to politicians and most voters.
DWill wrote:
Not only does our current release of carbon dwarf what agriculture caused, but Wadhams tells us that events like the meteor that hit the Yucatan, eliminated the dinosaurs, and eventually produced a rise of CO2 to 2,000 ppm are less potent contributors as well. I confess I have a hard time getting my mind around that, which may be broadly indicative of the stubborn inability of our minds to comprehend how billions tiny inputs have done what catastrophes could not.
The rise of CO2 after the extinction of the dinosaurs 65 million years ago seems to have caused global warming of five degrees, according to the linked research published in 2018. Wadhams cites research that says the meteorite caused warming over 10,000 years, but this newer paper suggests it was faster than that.
DWill wrote:
The key I suppose is that catastrophes in retrospect may seem to have been sudden, but their effects were actually spread out over a much longer period of time than the relative eye-blink of our fossil-fuel economy. The annual rate of rise is greater in our era.
It may be that the dinosaur meteorite provided a good comparison to the geological speed of current warming, after the initial few years of darkening caused by burning up the whole planet.


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Post Re: Ch. 3: A brief history of ice on planet Earth
Robert Tulip wrote:
DWill wrote:
We don't see the really sharp rise in CO2 beginning until about 1850, so I don't understand how our burning of wood and releasing methane through agriculture could have forestalled another ice age by itself. Isn't the threat all about the release of highly concentrated carbon that began only when we started mining coal?
The point here is to understand just how sensitive our planetary climate is to tiny effects, when those effects create a sustained small forcing in one direction for a long time. Before the transition from the stone age, invisible orbital and tectonic changes were enough to cause ice ages to start and end, operating on time scales of thousands and millions of years. Then, with the emergence of agriculture, the increase of atmospheric methane, although tiny by modern comparison, was still enough to counterbalance the radiative forcing of the orbital shift that in previous cycles had plunged the planet back into a new ice age. So what we are doing now is a complete recipe for catastrophe over any timescales longer than political elections, but the electoral cycle is the only timescale that matters to politicians and most voters.

I understand there is an argument that the human presence has tipped a balance that may mean the end to periodic warming and cooling--because we need to be in a Goldilocks zone for the pattern to continue. In reality, I think Wadhams speculates that our CO2 additions may delay, but not necessarily stop, the next ice age from happening. Whatever the case, I gather that the theory needs further support. What concerns me about accepting the theory that we had, as long as 3,000 years ago, already become forces in climate change is that it lets fossil fuels off the hook. The most solid data we have say that we arrived at a perilous state through the burning of all that concentrated carbon. If we had realized the danger sooner and backed off, we'd have had a chance to limit the damage. Now, it may be too late without extreme means such as geoengineering, but it wasn't always too late.



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Post Re: Ch. 3: A brief history of ice on planet Earth
DWill wrote:
I understand there is an argument that the human presence has tipped a balance that may mean the end to periodic warming and cooling--because we need to be in a Goldilocks zone for the pattern to continue.
Not just “may” – the anthropogenic changes to climate definitely spell an end to the ice age cycle. The only ways there will be new ice ages would be if civilization collapses and after a hundred thousand years the CO2e level falls by 50%, or if geoengineering measures cool the planet too fast. The “Goldilocks zone” generally refers just to the distance from the sun where the temperature is just right for water to remain liquid. You are interestingly using it much more narrowly within that liquid water band to mean the temperature where a tiny change in orbital pattern is enough that more snow falls in winter than melts in summer and glaciers increase in size, or vice versa. That only occurs at the very narrow specific band of temperature that our planet had for three million years until the Anthropocene.
DWill wrote:
In reality, I think Wadhams speculates that our CO2 additions may delay, but not necessarily stop, the next ice age from happening.
I did not read Wadhams as making that claim. His general view is that geoengineering is needed to stop dangerous warming. There is no way an ice age can happen with the amount of carbon now in the air. Rather, the earth system will eventually produce an equilibrium, whereby the sea level and ice mass adjusts to reflect the radiative forcing produced by the prevailing greenhouse gas chemistry. The current atmospheric composition is enough for about ten to twenty yards of sea level rise, based on the last time the planet had the current CO2 level four million years ago. The only point of scientific dispute and uncertainty about this is how long this equilibrium will take to emerge. The range of time to produce this earth system equilibrium from our current situation is generally estimated in centuries, but the unprecedented rapidity of the chemistry shift we have created through the scale of emissions means there may be factors able to cause polar ice melt far faster than these models indicate, flooding all coastal areas and destroying all beaches, ports and coastal lowlands and coral atolls around the planet. Wadhams discusses some of these factors in a later chapter, looking at how ice can be hollowed out like a Swiss cheese so it collapses far faster than predicted. Antarctica has enough ice to raise sea level by 200 feet.
DWill wrote:
Whatever the case, I gather that the theory needs further support.
The science of global warming is settled in broad outline, precluding any possibility of a surprise glaciation due to orbital factors. The choices are between a new hot stability, possibly quite inhospitable to humans, or a geoengineered stability, returning to Holocene norms. Emission reduction cannot be enough to stop a hothouse.
DWill wrote:
What concerns me about accepting the theory that we had, as long as 3,000 years ago, already become forces in climate change is that it lets fossil fuels off the hook.
Ruddiman’s hypothesis dates the onset of anthropogenic warming to 8000 years ago, when the emergence of Neolithic rice farming and their methane emissions caused departure from the previous orbital climate patterns. Talk of “letting fossil fuels off the hook” fails to engage with the serious urgency of the climate security crisis. It is essential to find collaborative responses that overcome the political polarisation inherent in the false idea that stopping burning of fossil fuels has to be the main climate policy. The disruption to the economy caused by mandating an end to burning already generates extreme political division, so the goal should be to find climate solutions that do, as you put it, let fossil fuels off the hook, together with the whole economic infrastructure that has been built on this foundation.
DWill wrote:
The most solid data we have say that we arrived at a perilous state through the burning of all that concentrated carbon. If we had realized the danger sooner and backed off, we'd have had a chance to limit the damage.
Your point here is widely assumed to be true, but is a non-sequitur. To ‘back off’ means to slow the speed of flow at which we add new carbon to the air. But the climate solution requires removal of the much larger stock of previously added carbon which has already committed dangerous warming, and against which the flow of new carbon is marginal. “Backing off” through an attack on fossil fuels was never going to be a primary climate solution. The key agenda is to work out how to transform existing CO2 into useful stable commodities at scale, such as plastic, concrete, fibre, roads, buildings and soil.
DWill wrote:
Now, it may be too late without extreme means such as geoengineering, but it wasn't always too late.
Yes it was always “too late” for emission reduction to work as a primary means to deliver climate stability. This is a key point of climate arithmetic which remains a basic stumbling block to implementing sensible policy.


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Post Re: Ch. 3: A brief history of ice on planet Earth
Robert, I'm struggling a bit to understand your POV on carbon, and that's what I'll ask about now rather than other specifics you've just addressed. In my view, and I think that of Wadhams and all other climate scientists whose claims I've read about, we've dumped too much CO2 into the atmosphere starting with the advent of the Industrial Revolution. While we were affecting climate to some degree before this ramping up, the impact must have been such that we were not competing with natural events such as volcanic eruptions. We didn't have the oomph, with our wood fires that have much less impact on CO2 levels than fossil fuels have.

Our problem is of course the high level of CO2 (and some other gases) that we've sent up. Yet from what I hear you saying, there was never a time when a rational approach would have been to cut back on those emissions. If your reason for thinking this is that by cutting back we would never have been able to reverse what we've done, taking the planet back to Holocene conditions, I see the logic, but I again would have to question the particular goal. I surmise that the scientific support for geoengineering is for the less drastic goal of stemming the planet's warming, in concert with decarbonizing--buying us time. It will make a crucial difference to have 2 degrees C of warming vs. 4--or 6. That goal may seem to be less than a moonshot, less than inspirational, but it involves in fact a tremendous effort. In any case, geoengineering would have to begin slowly and tentatively in order to determine its effectiveness and safety.

Maybe I'm wrong about where Wadhams sits on that question. I'll find out soon. But I do see you being somewhat at variance with his general view of when and how we became climate change agents.



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Post Re: Ch. 3: A brief history of ice on planet Earth
DWill wrote:
Robert, I'm struggling a bit to understand your POV on carbon, and that's what I'll ask about now rather than other specifics you've just addressed. In my view, and I think that of Wadhams and all other climate scientists whose claims I've read about, we've dumped too much CO2 into the atmosphere starting with the advent of the Industrial Revolution. While we were affecting climate to some degree before this ramping up, the impact must have been such that we were not competing with natural events such as volcanic eruptions. We didn't have the oomph, with our wood fires that have much less impact on CO2 levels than fossil fuels have.
Wadhams explains that global warming is a function of radiative forcing. Greenhouse gases cause only two thirds of total anthropogenic warming. The remaining third is caused by climate feedbacks such as the ice-albedo feedback from melting snow and ice, which itself causes half as much warming as the GHGs, shifting natural systems from white reflectors to black absorbers of heat. Of the GHG effect, CO2 only causes two thirds. Methane is a quarter, and other gases the remainder. The CO2 dump is a main accelerator of warming, but only delivers half the radiative forcing effect of all human warming sources. Warming feedback effects are accelerating with the melting Arctic as a primary cause. The methane warming effect of human technology long predates the CO2 dumping that began at scale with the coal steam process in England. Thousands of years before the present, rotting of rice fields was enough to outweigh the natural orbital forcings back to an ice age. Our modern emissions have of course completely overwhelmed the small slow sensitive systems that in former similar orbital periods sent the planet back into ice ages every one hundred thousand years, a prospect that is now impossible.
DWill wrote:
Our problem is of course the high level of CO2 (and some other gases) that we've sent up. Yet from what I hear you saying, there was never a time when a rational approach would have been to cut back on those emissions.
Imagine if in 1990 the world decided to abolish carbon emissions as rapidly as possible. Firstly, no alternative energy would have been in place. Secondly, and more importantly, the 0.3 or so trillion tonnes of carbon that humans had already added to the air before 1990 would have continued its insidious chemical effect on earth climate systems, generating a path back towards eventual equilibrium, with less ice and higher seas. The only decisive change to prevent sea level rise is to end this chemical distortion of the Holocene equilibrium by physically removing all that prior emitted carbon, ideally transforming it into useful products. When that is underway, emissions can gradually reduce in line with economic needs. Emissions are 15 gigatonnes of carbon per year (GtC). Net zero will occur when removals equal emissions, at whatever level. The most feasible path is to increase removals to the level of emissions, and then much higher, to end the risk of tipping points into committed warming from past emissions. I think a feasible goal for net zero by 2030 is to cut annual world emissions by 1 Gt and increase removals by 14 Gt, aiming for stable emissions and rapidly increasing removals, up to perhaps 50 GtC/y by 2050.
DWill wrote:
If your reason for thinking this is that by cutting back we would never have been able to reverse what we've done, taking the planet back to Holocene conditions, I see the logic, but I again would have to question the particular goal.
Holocene stability should be the essential core planetary security goal, through urgent re-freezing of the Arctic to prevent dangerous sea level rise and climate disruption. This is as much a military perspective on security as an ecological one.
DWill wrote:
I surmise that the scientific support for geoengineering is for the less drastic goal of stemming the planet's warming, in concert with decarbonizing--buying us time.
The ratio between removals and decarbonising over the next decade should aim for 15:1 to deliver planetary net zero by 2030. Any higher allocation to emission reduction than about this 7% of total cooling forcing has severe opportunity cost and risk of failure.
DWill wrote:
It will make a crucial difference to have 2 degrees C of warming vs. 4--or 6.
Indeed, but the Paris Accord is shooting for 4°C in reality, since the lower targets can only be achieved by a global change of policy to focus on immediate coordinated carbon removal.
DWill wrote:
That goal may seem to be less than a moonshot, less than inspirational, but it involves in fact a tremendous effort.
. Increasing the rate of emission cuts is a misdirected effort. The funds now directed to the energy transformation could achieve far bigger cuts to the key metric of radiative forcing by application of scientific methods of climate management, primarily carbon removal, but also albedo enhancement. My proposed albedo enhancement method is to thicken polar sea ice by tidal pumping. This has not been previously considered in scientific models.
DWill wrote:
In any case, geoengineering would have to begin slowly and tentatively in order to determine its effectiveness and safety.
That is very true, and can only occur through large injections of public funds in partnership with the private sector, mainly the oil industry. My view is that Pacific Ocean nations should combine to work out the best ways to use the Pacific Ocean to remove carbon, as a main strategy to preserve political and military peace and stability, as well as ecological biodiversity. The USA and China could lead such a cooperative research and development agenda.
DWill wrote:

Maybe I'm wrong about where Wadhams sits on that question. I'll find out soon. But I do see you being somewhat at variance with his general view of when and how we became climate change agents.
Wadhams does not cite Ruddiman’s Neolithic methane rice hypothesis, but their work is entirely coherent and compatible. Wadhams emphasises the massive methane effect which Ruddiman also drew attention to. Drivers of warming in addition to CO2, especially the fast looming catastrophe of methane release from the melting of the Arctic, are singing in concert with the whole range of accelerating warming feedbacks driven by our darkening of the grand refrigerators of our planet from white toward black.


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Post Re: Ch. 3: A brief history of ice on planet Earth
So what we have, in sum, is the fortunate situation of now having a solution that we could not have had in eras previous--geoengineering. If we could never have applied an effective solution until we happened onto the technology--which arguably could be now--we should be glad for our opportunity to finally fix the climate, and not indulge in senseless regret for all that excess CO2. I think your advice is for us to approach our task as a matter of 'industrial ecology.'

This is certainly a weird place to be. We had to pollute the planet's atmosphere for all those years, waiting for technology that could undo the pollution. Maybe we will after all be able to employ some solar geoengineering as one mode of attack, but only one. Carbon removal seems to have a much better chance of political and public acceptance, though I gather it will be more expensive to apply. Then there is emissions reduction, which although not a way by itself to avoid short-term suffering, has to (I think the imperative applies) be seriously pursued because the whole point will be someday not to rely on extraordinary means of climate control. Solar geoengineering isn't a one-time thing, but has to be continuously applied in most cases that are being thought up.

I can't agree with trying to return the planet to Holocene conditions, and I think that most scientists and others working on this most pressing of problems realize that our resourcefulness will be needed not just to slow warming but to adapt to degrees of warming--how many degrees, we don't know for sure, but we can be either well or poorly prepared. It's like knowing we can't prevent the storm from hitting, but we can better weather its effects through defense. Climate justice is the concept most relevant here. Will wealthier people and more developed countries receive the lion's share of the benefits of protective measures?



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Robert Tulip
Wed Jul 29, 2020 9:56 pm
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