A Farewell to Ice: A Report from the Arctic
by Peter Wadhams
by Peter Wadhams
Please use this thread to discuss Ch. 3: A brief history of ice on planet Earth.
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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.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.
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.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.
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.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.
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 weRobert 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.
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: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 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: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.
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.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.
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.Robert Tulip wrote: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: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 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: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.
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: In reality, I think Wadhams speculates that our CO2 additions may delay, but not necessarily stop, the next ice age from happening.
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: Whatever the case, I gather that the theory needs further support.
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: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.
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: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.
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.DWill wrote: Now, it may be too late without extreme means such as geoengineering, but it wasn't always too late.
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: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.
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: 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.
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: 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.
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: 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.
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:It will make a crucial difference to have 2 degrees C of warming vs. 4--or 6.
. 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: That goal may seem to be less than a moonshot, less than inspirational, but it involves in fact a tremendous effort.
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:In any case, geoengineering would have to begin slowly and tentatively in order to determine its effectiveness and safety.
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.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.