From the UNIVERSITAT AUTONOMA DE BARCELONA and the “department of settled science” comes another global climate thermostat story. Just last week, we were told the Earth had no thermostat. Gotta love it when climate science is so robustly definite, eh?
Ice age thermostat prevented extreme climate cooling
Atmospheric CO2 concentrations swung over a range of 100 ppm (parts per million, by volume) during the ice ages. The exact processes behind this variation have been difficult to pinpoint, but it is known that changes in the storage of carbon by photosynthetic organisms played an important role.
“When we took a close look at measurements from ice cores, we noticed that atmospheric CO2 concentrations hovered close to 190 ppm during much of the past 800,000 years, but very rarely fell any lower,” said Sarah Eggleston, a researcher at the Institut of Environmental Science and Technology (ICTA-UAB) and co-author of the study. “This was surprising, because it suggests that these very low CO2 concentrations were quite stable. What’s more, we know that CO2 was often very high in the distant geological past, but we have no evidence that CO2 concentrations were ever lower than 190 ppm.”
“We know that, over hundreds of thousands of years, CO2 is regulated by slowly reacting with exposed rocks” explained Eric Galbraith, lead author of the study and an ICREA professor at ICTA-UAB. “But this would be too slow to explain the stability during periods of only a few thousand years, as we see in the ice cores. So it must have been some other mechanism that kicked in at very low CO2.”
The authors suggest that it was most likely the biosphere that maintained habitable temperatures, since at very low CO2 levels, plants and phytoplankton struggle to photosynthesize. Slower growth of these organisms would have meant less carbon in the soils and deep ocean leaving more in the atmosphere, and preventing CO2 concentrations from falling further. This might have prevented extreme cooling that would have led to Earth freezing over as a ‘snowball’.
However, the study did not reveal a corresponding regulation during the warm portions of the ice age cycles, suggesting that the Earth does not have a similar mechanism to prevent rapid warming.
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A lower limit to atmospheric CO2 concentrations over the past 800,000 years
Global temperatures and atmospheric CO2 concentrations varied widely over the glacial cycles of the past 800,000 years. But despite this variability, Antarctic ice cores have shown that CO2concentrations were very similar during all the coldest points of these cycles. Remarkably, the recurring minimum CO2 concentrations (190 ± 7 ppm) fall on the lower bound of any known in Earth history. Here we show that although the volume of terrestrial ice sheets was normally distributed over the past 800,000 years, as might be expected from the approximately normal distribution of the orbital forcing that drove the glacial cycles, Antarctic temperatures have a strong cold mode, whereas CO2 concentrations have both a cold mode and a central mode. Although multiple explanations are possible, the recurring CO2 minima and pronounced cold modes are consistent with a strong negative feedback to decreasing CO2 that resisted further cooling on timescales shorter than 10,000 years. We suggest that one possible negative feedback is CO2-limitation of photosynthesis, either directly or via CO2-limitation of N2 fixation, which could have inhibited further lowering of CO2 by reducing carbon storage.
Full paper: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2914.html (paywalled)
The smartest thing ever invented is the thermos flask.
It keeps the hot food hot; and it keeps the cold food cold.
How the hell does it know ??
Everybody enrolling in a climate change class, should be given their own personal thermos flask.
G
Archived in the drawer of nice conjectures without supporting evidence.
Why do these articles so rich in speculation and so poor in evidence keep being published?
The ice ages of the past ~3.2 My are certainly an anomaly in Earth’s geological history of the past 600 My.
And it came damn close to biosphere death, To Wit:
“Remarkably, the recurring minimum CO2 concentrations (190 ± 7 ppm) fall on the lower bound of any known in Earth history. ”
The clueless climatist bedwetters think that even 285 ppm CO2 is ideal, merely for a political agenda that has at its core UN Agenda 21 and global socialism. Just today, Gavin Schmidt dishonestly posted on his Twitter feed his beyond idiotic “belief” that 100% of the Earth’s warming since 1950 is anthropogenic. I’d agree only to the point that the has been no real warming since 1940-45, and the warming 1950 is merely mand-made synthetic manipulations of data.
If the Earth gets to 650-700 ppm by the end of the easy fossil fuel era (~100 to 200 yr from present) , we will likely have a climate and biosphere optimum. And we’d better have fossil fuel’s nuclear (fission and/or fusion or even exotic single point energy) power replacement in place globally. The clock is ticking.
The oceans hold huge amounts of CO2. I would think they would be a better regulator than plants.
Even during ice ages, a large part of the oceans remain ice free.
This might have prevented extreme cooling that would have led to Earth freezing over as a ‘snowball’….
………”the positive feedback loop takes over and the runaway snowball effect is pretty much unstoppable”
8-/
CO2 has negligible effect on temperature after the first 100 ppm. Most plants however need a higher level than that to grow healthily and reproduce.
Related topic: A great NatGeo article on the starkly beautiful “channeled scablands” of eastern Washington State. And (surprise!) no mention of “carbon” or “climate change”, but, rather, a cautionary tale of scientific “consensus” and intransigence:
http://news.nationalgeographic.com/2017/03/channeled-scablands/
Earth has a thermostat. Sort of. Only it doesn’t work the way these “scientists” think it does. CO2 isn’t even one of the knobs, just along for the ride pretty much. It’s a crazy quilt kind of thermostat, which we’ve only started to get a handle on.
“When we took a close look at measurements from ice cores, we noticed that atmospheric CO2 concentrations hovered close to 190 ppm during much of the past 800,000 years, but very rarely fell any lower,” said Sarah Eggleston, a researcher at the Institut of Environmental Science and Technology (ICTA-UAB) and co-author of the study. “This was surprising, because it suggests that these very low CO2 concentrations were quite stable.
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They have took a close look at the measurements from ice cores…….really hilarious……..wondering how good their minds are to make any sense out of the ice core measurements……gosh.
There from the very start, lying out of their teeth……
cheers
Does anybody have a chart of the correlation of CO2 with temperature as a function of interval from past to present ? Ie : over the last 1K , 1M , 10M .. intervals ? Is it significant for any of those intervals ?
“…suggesting that the Earth does not have a similar mechanism to prevent rapid warming.”
It doesn’t suggest such a thing. This unscientific phrase undoes whatever good this paper might have. In simple minds, because they suggest a lower limit to the level CO2 will reach because of limited photosynthesis, they assume that photosynthesis is the only mechanism for removing CO2 from the atmosphere and therefore unbounded heating can take place with increases in CO2. I take issue, as most would, with their first simple idea that this limits how cold it can get. CO2 isn’t the only actor in temperature – the control knob CO2 idea has been torpedoed incessantly over the past couple of decades as well as shown in paleo data. A large volcanic explosion would put aerosols in the atmosphere and undersea ones could warm the ocean particularly in the Pacific Ring of Fire , a huge earth quake and Tsunami would break up ice and allow direct insolation, the sun can vary, geothermal heat is always heating from below and even under antarctic and arctic ice caps water is liquid from this – there is a lake with life in it beneath several km of ice in Antarctica. Indeed, the sun itself has a limiting factor on how cold it can get – why do you think planets get colder the farther out you get. How about Titan with methane seas and atmosphere – a gas that is according to legend a thousand times more powerful a greenhouse gas than CO2 ………………
Using a proxy record (ice cores) that has been demonstrated convincingly to show that CO2 levels FOLLOW temperature trends with a lag of about 800 years, they were able to conclude that CO2 levels were somehow controlling how cold it can get?
Holocene ice core records consistently exemplifies that atmospheric CO2 concentrations follow temperature, not the other way around. So the authors premise that a CO2 floor of 190 ppm is a thermostat limit, does not make sense. As Patrick Moore has stated on this website, Photosynthesis shuts down at about 180 ppm, That could well explain the CO2 bottom limit, but it has little to do with temperature modulation.
Three articles down is a paper explaining why/ how snowball earth did in fact occur. So on one random wuwt front page two research teams flatly contradict each other, whilst yet managing not to cross-refer. Funny old world innit?
If the authors wanted to speculate on the subject of atmospheric levels not dropping much lower than 190 ppm, the likely speculations would have been…was the ocean saturated?…did ice cover block further CO2 absorption?…were volcanoes continuously spewing CO2?…etc
The least likely areas to speculate upon are …was plant life starved off to the point plants no longer absorbed CO2 from the atmosphere?…. did the world cease cooling off because CO2 levels ceased dropping?
SR
At 190 ppm plants had to be stressed. Plants die at 150 ppm. And the plants that were living were probably puny.
Obviously the authors aren’t acquainted with the ocean/atmosphere interaction–it’s all very simple if you look at the oxygen isotope/CO2 curves. CO2 always lags atm temp–i.e., the temperature of the oceans are the limiting factor
To be or not to be–a global thermostat. Brought to you by the Globe Theater and its resident Bard. A farce in two acts.
Any ice core guys on this thread?
I have read that the ice cores are very misleading on both end of the bell curve. That is, they miss the big peaks and valleys in the data because of diffusion of gas in the snow as it is being compacted into ice.
Is this accepted? And, if so, how would that impact this sort of paper?
They should have looked for methane. When the plants die they decompose and produce methane, which as all know is a very potent GHG. Case solved, send the money immidiately.
Of course there was a thermostat and there was not a thermostat. That is in the past. Climate science cannot tell us anything about the past. Not even what a thermometer measured 20 years ago.
All that has nothing to do with the future.
Climate Science has absolute faith in the future. The Science is Settled.
Does anyone find it odd that in this most ‘settled ‘ of sciences that the ‘heads you lose , tails I win ‘ approach is seen so often ?
It meets the ‘reasonableness test’ to explain a low limit of CO2 because of plant growth. Plants get all their carbon from CO2. With low CO2 there is little to ‘consume’ and therefore less is deposited or sequestered and taken out of the system. As less and less is sequestered, there is less to decompose back to CO2. As a result a lower limit is approached.
One of the most profound undergrad chemistry lectures I can remember all those years ago was about equilibrium reactions. Its amazing how many times that concept has come up in later life.
When a system is in equilibrium, the chemical/physical reactions move in a direction to offset the effect of an external influence. These equilibrium reactions, in balance, can stop the system running away to extremes.
For the earth sea-atmosphere system one has to think that the various liquid-gas reactions in equilibrium have two extreme endmembers: an interglacial earth, and a glacial earth. Probably thats as far as the climate goes in each direction, although in geological history it is suspected that the whole earth has been glaciated.
Its tempting to think that the external influence (variations in the sun insolation plus orbital variations) drives the equilibrium to variations in water evaporation, cloud formation and rainfall, leading to surface climate variation.
The idea that CO2 below 100ppm would cause runaway cooling is just as bogus as claims of runaway warming, the models of both presume 1) CO2 drives temperature and 2) there’s an infinite source of Joules to power the gain (per the Bode model). Consider an electronic amplifier (the model used) with the signal input and the power supply input connected together (the bogus presumption that the assumed, infinite source of Joules is the Sun). Will you ever get more power out of the amplifier than is going in to the power supply input?
The idea that biology keeps CO2 levels from dropping below about 100 ppm is absolutely correct since biomass is still thriving in tropical regions, moreover; biology also contributes to why CO2 lags temperature. It takes a while for biomass to populate and maximally utilize land whose ice covering has melted away. Going the other way, it takes a while for snow to accumulate deep enough to kill off alpine and other cold tolerant forests.