From the University of Bristol
Carbon cycling was much smaller during last ice age than in today’s climate
Atmospheric carbon dioxide (CO2) is one of the most important greenhouse gases and the increase of its abundance in the atmosphere by fossil fuel burning is the main cause of future global warming. In past times, during the transition between an ice age and a warm period, atmospheric CO2 concentrations changed by some 100 parts per million (ppm) – from an ice age value of 180 ppm to about 280 ppm during warm periods.
Scientists can reconstruct these changes in the atmospheric carbon stock using direct measurements of atmospheric CO2 trapped in air bubbles in the depth of Antarctica’s ice sheets. However explaining the cause of these 100ppm changes in atmospheric CO2 concentrations between glacial and interglacial climate states – as well as estimating the carbon stored on land and in the ocean – is far more difficult.
The researchers, led by Dr Philippe Ciais of the Laboratoire des Sciences du Climat et l’Environnement near Paris, ingeniously combined measurements of isotopes of atmospheric oxygen (18O) and carbon (13C) in marine sediments and ice cores with results from dynamic global vegetation models, the latter being driven by estimates of glacial climate using climate models.
Dr Marko Scholze of the University of Bristol’s School of Earth Sciences, co-author on the paper said: “The difference between glacial and pre-industrial carbon stored in the terrestrial biosphere is only about 330 petagrams of carbon, which is much smaller than previously thought. The uptake of carbon by vegetation and soil, that is the terrestrial productivity during the ice age, was only about 40 petagrams of carbon per year and thus much smaller: roughly one third of present-day terrestrial productivity and roughly half of pre-industrial productivity.”
From these results, the authors conclude that the cycling of carbon in the terrestrial biosphere – that is, the time between uptake by photosynthesis and release by decomposition of dead plant material – must have been much smaller than in the current, warmer climate.
Furthermore there must have been a much larger size of non-decomposable carbon on land during the Last Glacial Maximum (the period in the Earth’s history when ice sheets were at their maximum extension, between 26,500 and 19,000 years ago).
The authors suggest that this inert carbon should have been buried in the permanently frozen soils and large amounts of peat of the northern tundra regions.
Paper
‘Large inert carbon pool in the terrestrial biosphere during the Last Glacial Maximum’ by P. Ciais, A. Tagliabue, M. Cuntz, L. Bopp, M. Scholze, G. Hoffmann, A. Lourantou, S. P. Harrison, I. C. Prentice, D. I. Kelley, C. Koven and S. L. Piao in Nature Geoscience
Sorry about the blockquote mess-up. My computer is so slow it took five hours to write that and it is almost impossible to edit due to the time lag. (Santa please bring me a newer computer for Christmas)
Gail Combs says:
November 22, 2011 at 7:20 am
We are told that the CO2 in the atmosphere is “well mixed” so a reading at Mauna Loa or in the Antarctic represent the CO2 of the entire world.
Mauna Loa, Barrow (Alaska) and the South Pole + near 70 other stations + ships surveys + airplanes + tall towers over 200 m height represent 95% of the atmopshere. The 5% not represented is where the plants grow: the first few hundred meters over land. Measurements there have show very little resemblance with the “background” levels measured everywhere else. It is the equivalent of measuring temperature on a hot asphalt parking lot. Here the difference between a few days at Giessen, Germany, with Mauna Loa, Barrow and the South Pole. Giessen is the place where lots of historical data were taken, which is the base of the 1942 “peak” in the data of the late Ernst Beck, all raw (half) hourly CO2 levels:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/giessen_background.jpg
Here the monthly averages for the same place, compared to MLO:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/giessen_mlo_monthly.jpg
So at dawn the plants sucked down 50 ppm in a just a few minutes not in a few hours. – BIG DIFFERENCE. (Efficient little buggers aren’t they.)
Except that the open air is not the same as a closed canopy. Especially as sunshine heats up the ground/plants and stirrs up the exchanges with the surrounding/above atmosphere… Or a little wind will do a lot of good… See the above CO2 graph from Giessen.
Thus even at 180 ppmv “background” plants may survive on land, be it far from optimal…
Roger Longstaff says:
November 22, 2011 at 4:21 am
About Beck’s data and stomata data:
Stomata data have the same problem as many of the historical data: taken over land where huge differences can be found between day and night, wind direction, sun or rain,… even within 15 minutes. As in previous post, the Giessen data, the cornerstone of Beck’s 1942 “peak” has an enormous variability. The historical data were taken three times a day (7 AM, 2 and 9 PM) where 2 were at the moment of the fastest transition in CO2 levels… The historical samples show a one-sigma variability of 68 ppmv. Completely worthless to know anything about the CO2 levels in the bulk of the atmosphere. CO2 data from seaships and coastal with wind from the seaside show levels around the ice core measurements. Unfortunately, there are no seaside measurements in the period 1935-1950.
Further, the stomata data don’t show any specific change in CO2 level around 1942. If there was a real peak of 80 ppmv up and down, the stomata data would go off-scale.
Stomata data are calibrated for the past century against direct measurements and ice cores. That compensates for the local bias, but that doesn’t give any confidence for data further back in history, as the local bias can change a lot, because of land use changes. E.g. in The Netherlands, where one of the main stomata indices is based on oak leaves, the landscape changed tremendously from sea to polders, from marshes to agriculture and forests in the main wind direction. Even the main wind direction may have been different e.g. during the LIA…
The fact that the average of the stomata data is above the ice core data shows that the local bias changed. While the resolution of ice core data is much less than of the stomata data, that doesn’t change their average. Thus the average of the stomata data should be the same as the average of the ice cores over the same period…
Ferdinand Engelbeen says:
November 22, 2011 at 8:15 am:
Thank you for your response. This is common to many who question Beck’s conclusions. However, I would advise anybody here who is confused to read Beck’s paper very carefully, and draw your own conclusions. Beck states that he carefully selected historical measurements in order that background CO2 concentrations could be monitored, away from any anthropogenic influences, including over the oceans. Nobel laureates were involved with this work and I do not think that it can be dismissed.
As I stated before, my personal opinion is that I would place greater reliance on chemical and stomata data rather than ice core data, given the uncertainties involved with all of the methods.
Roger Longstaff says:
November 22, 2011 at 8:39 am
Roger, I had a few years personal discussions with the late Ernst Beck. The main problem is that he used all available data, the good, the bad and the ugly, lumped them all together and averaged them.
I downloaded all his data and descriptions of the methods for the period 1935-1950, where the 1942 “peak” of 80 ppmv is situated. There were lots of problems with data and especially the places where was measured, like Giessen in the other message. Sometimes the place was OK, but the apparatus was far too inaccurate. He included e.g. data from Barrow (a perfect place) taken with an apparatus, the micro-Schollander method, accurate to +/- 150 ppmv. No problem for measuring exhaled air, which was its purpose, but worthless for background CO2 measurements at around 300 ppmv.
You need to look at what a change of 80 ppmv in only 7 years up and down in reality means:
– or burning of 1/3rd of all land vegetation on earth and regrowth each in 7 years.
– or an increase of 5°C in average sea surface temperature and back (purely based on Henry’s Law, not taking into account that vegetation acts in opposite way).
– or a strong acidification of the ocean surface (with what?) and an equal alkalisation thereafter.
– or the outburst of thousands of volcanoes all together, but there is no equivalent removal in such a short period.
While it is theoretically possible to have such a sudden increase of CO2, it is physically impossible to remove such a huge extra amount of CO2 in less than 7 years. The current removal rate at 100+ ppmv above steady state for the current temperature is 2 ppmv/year. A linear removal of 80 ppmv would take at least 40 years, but as the removal rate is in ratio with the pressure difference, only halve of the 80 ppmv is removed in 40 years, 20 ppmv in the next 40 years,…
Gail Combs says:
November 21, 2011 at 6:01 am
Aside from the plants during the Ice Age showing the CO2 reading are way off there is another elephant in the room.
It is called Water Vapor.
95% of the green house effect is caused by WATER not CO2. It is up to 4% where as CO2 is a puny 0.036% That is why water is left out of the IPCC reports. (Another lie by omission) http://www.geocraft.com/WVFossils/greenhouse_data.html
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They’ve left out water vapour because they had to, to include it would be to include The Water Cycle, and that means, their meme about ‘greenhouse gases warming the planet’ goes unchallenged because unrecognised – it appears that both pro and anti AGW haven’t looked at the basic premise…
I’ve challenged it here: http://wattsupwiththat.com/2011/11/13/slipping-some-past-the-goalie-at-rc/#comment-802016
Greenhouse gases cool the atmosphere. This basic premise of the AGWScienceFiction energy budget is junk science, totally made up. I don’t understand why this hasn’t been picked up by the ‘heavyweights’ arguing against AGW – just as I can’t understand why both pro and antis accept without question the other base premise of the AGWSF energy budget – that visible light heats land and oceans.. This is fantasy physics. They’ve excluded Thermal Infrared, the real heat direct from the Sun warming land and oceans and us, just as they have excluded the whole of the Water Cycle.
It’s astonishing.
Ferdinand,
Thanks for the links. The only one with more than a summary was the ScienceDaily article, which of course needs to be taken with a mountain of salt, as always. It states: “”We know from looking at much older climate records that large and rapid increase in CO2 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic,” he said. “We’re heading in that direction now.””
There is no verifiable, testable evidence that ocean pH has measurably changed due to higher CO2 levels, and I would need to see credible evidence that a rise in CO2 55 million years ago [and not something else] “caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic”. The person quoted appears to not understand buffering.
Also, the Jarowoski et. al paper spent considerable analysis on the capillaries of liquid water interlaced deep under the ice. If this is factual, then there is a way for CO2 to migrate through the ice since CO2 is very soluble in cold water. But maybe I misunderstood your reasoning.
Next, you previously convinced me [with much patience, which I appreciate] that human emissions of CO2 are the primary reason for current atmospheric levels. However, I believe that Dr Beck’s research cannot be entirely discarded. The scientists who took CO2 readings were careful to stay on the windward sides of ships crossing all of the world’s major oceans, and took measurements on desolate windswept seacoasts and on mountain peaks. They were not government scientists looking for grants, but were actually trying to take accurate measurements. And they knew their work would be critiqued by their peers; errors and mistakes would tarnish their reputations at a time when reputations were everything to a scientist. I agree that some urban measurements are very suspect. But how do you explain the thousands of high CO2 measurements taken on the windward side of ships sailing across the South Pacific, the Sea of Okhotsk, the Atlantic, the Pacific, the Arctic, etc?
[For those interested in Beck’s work]:
click1
click2 [interactive site; click on lower right numbers]
click3 [Beck et. al peer reviewed paper]
Finally, the discussion always seems to gravitate to the rise in CO2, and stop there. But we should not forget that there were endless predictions of climate disruption, runaway global warming, rapid sea level rise, and other crises that would be caused by a rise in CO2. We should keep in mind that none of those dire predictions occurred. In fact, there is no scientifically credible evidence showing any global harm due to the rise in CO2, and there is much evidence that the increase has been beneficial to the biosphere. Therefore, there is something wrong with the AGW conjecture. At the very least, it has been wildly overstated.
RE: Main Article
“Scientists can reconstruct these changes in the atmospheric carbon stock using direct measurements of atmospheric CO2 trapped in air bubbles in the depth of Antarctica’s ice sheets.”
Given the long duration of time since these bubbles or voids were formed, I am skeptical that they still retain their original gas concentration levels unconatminated by absorbtion or out-gassing from their surrounding matrix. I presume that Henry’s Law applies to solids as well as liquids.
believe says:
November 22, 2011 at 7:04 pm
Sorry for the late reply… Some interesting things happening with the release of thousands of CRU emails again…
The Science Daily article indeed needs to be taken with a lot of salt… The extinction that happened 55 million years ago has no connecttion to what happens today, even the real cause is uncertain…
Also, the Jarowoski et. al paper spent considerable analysis on the capillaries of liquid water interlaced deep under the ice. If this is factual, then there is a way for CO2 to migrate through the ice since CO2 is very soluble in cold water. But maybe I misunderstood your reasoning.
In theory, for pure ice, there is a small layer of unordered, waterlike watermolecules at the ice surface-air boundary. That layer goes from a few micrometer at near melting to 5 atoms thick at -30°C and zero below -32°C. Thus still present at -20°C to -24°C for the coastal ice cores. As the measurements standard are done by crushing the ice at clod temperatures under vacuum over a cold trap (-70 to -80°C) that effectively removes all eventual dissolved CO2 from that layer. And the cold trap removes any water vapour that is coming along. That forms a closed layer where only some CO2 can adhere to the surface, but that is compensated for by using calibration mixtures before and after the tests.
The structure at the border between ice crystals is semi-ordered, by the influence of both crystals and is far less waterlike than at the surface. Thus less possibility for CO2 to enter and diffuse through the mass. If you have two cold spheres of ice, the waterlike surface will recrystallize when you touch the two together and only with a lot of force you can brake the bound.
What Jaworowski has done is describing the literature where contamination in the ice was found, in that case sulphuric acid. That can be seen in detail as inclusions mostly at the triple points of ice crsytals. But without channels along the borders…
Nevertheless. If there were sufficient channels with liquid water, there is a possibility that CO2 can migrate over time. The result of migration is that the highs and lows are flattening. Thus the resolution goes down and the higher frequency variations aren’t visible. That would mean that difference in CO2 levels between warm and cold periods would disappear. For ice ages / interglacials the difference in period of time is about 90/10, thus a complete migration would show a uniform level of about 190 ppmv i.s.o. 180-280 ppmv. But even the slightest migration should show that the highest levels farther back in time would decrease for each interglacial/glacial period. That is not the case. So we can say that for the coldest (-40°C) Vostok and Dome C ice cores, there is no measurable migration over 800,000 years.
About Beck’s data, much is already said. The data taken over the oceans and coastal with seaside wind are around the ice core values. I have no plot of the seaside data only, but have a look at all of Beck’s data in the period 1930-1950:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/beck_1930_1950.jpg
Almost all minima of the near always enormous ranges are below the ice core values for even the worst non-ocean/coastal data. The fact that you have such an enormous range in measurements in the same year at the same place (Giessen: 68 ppmv – 1 sigma, +100 ppmv in five months…) is proof that there were huge local/regional sources and sinks at work and/or huge variability in method or handling of the sample, reagens, etc… Further, it is impossible that in the same year at one side of the earth one finds 250 ppmv and at the other side 450 ppmv. Even balloon levels which are much higher than ground levels, which is physically impossible after a period of low ground levels… Some of them and probably all must be wrong…
In my opinion: forget the historical data, at least all those taken over land…
But you are right: the real fight is about the (lack of) influence of CO2 on climate. Therefore I wonder why so many skeptics insist on (alleged) problems with ice cores, which are proven reliable. That doesn’t make their case any stronger…
Spector says:
November 24, 2011 at 11:14 pm
Given the long duration of time since these bubbles or voids were formed, I am skeptical that they still retain their original gas concentration levels unconatminated by absorbtion or out-gassing from their surrounding matrix. I presume that Henry’s Law applies to solids as well as liquids.
The newest method, mainly used for extreme accuracy necessary for isotopes ratio measuring, is by sublimating all ice at just below melt temperature with an IR lamp. All substnaces are frozen at cryogenic temperatures and cryogenically separated and individually measured. That recovers over 99% of all CO2, wherever that might hide. The normal method by ice crushing under vacuum gives the same results for CO2 in air levels. Thus not much CO2 is hiding in the ice matrix…