Ancient global warming: but which came first, the temperature or the CO2?
From the National Oceanography Centre, Southampton (UK)
Variations in atmosphere carbon dioxide around 40 million years ago were tightly coupled to changes in global temperature, according to new findings published in the journal Science. The study was led by scientists at Utrecht University, working with colleagues at the NIOZ Royal Netherlands Institute for Sea Research and the University of Southampton.
“Understanding the relationship between the Earth’s climate and atmospheric carbon dioxide in the geological past can provide insight into the extent of future global warming expected to result from carbon dioxide emission caused by the activities of humans,” said Dr Steven Bohaty of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre in Southampton.
It has been known for some time that the long-term warmth of the Eocene (~56 to 34 million years ago) was associated with relatively high atmospheric carbon dioxide levels. However, scientists were previously unable to demonstrate tight-coupling between variations in atmospheric carbon dioxide and shorter-term changes in global climate.
To fill this gap in knowledge, the authors of the new study focused on one of the hottest episodes of Earth’s climate history – the Middle Eocene Climatic Optimum (MECO), which occurred around 40 million years ago.
Algae use photosynthesis to harvest the energy of the sun, converting carbon dioxide and water into the organic molecules required for growth. Different isotopes of carbon are incorporated into these molecules depending on the environmental conditions under which algae grow. Ancient climate can therefore be reconstructed by analysing the carbon isotope ratios of molecules preserved in fossilised algae.
The researchers took this approach to reconstruct variations in carbon dioxide levels across the MECO warming event, using fossilised algae preserved in sediment cores extracted from the seafloor near Tasmania, Australia, by the Ocean Drilling Program. They refined their estimates of carbon dioxide levels using information on the past marine ecosystem derived from studying changes in the abundance of different groups of fossil plankton.
Their analyses indicate that MECO carbon dioxide levels must have at least doubled over a period of around 400,000 years. In conjunction with these findings, analyses using two independent molecular proxies for sea surface temperature show that the climate warmed by between 4 and 6 degrees Celsius over the same period.
“We found a close correspondence between carbon dioxide levels and sea surface temperature over the whole period, suggesting that increased amounts of carbon dioxide in the atmosphere played a major role in global warming during the MECO,” said Bohaty.
The researchers consider it likely that elevated atmospheric carbon dioxide levels during the MECO resulted in increased global temperatures, rather than vice versa, arguing that the increase in carbon dioxide played the lead role.
“The change in carbon dioxide 40 million years ago was too large to have been the result of temperature change and associated feedbacks,” said co-lead author Peter Bijl of Utrecht University. “Such a large change in carbon dioxide certainly provides a plausible explanation for the changes in Earth’s temperature.”
The researchers point out that the large increase in atmospheric carbon dioxide indicated by their analysis would have required a natural carbon source capable of injecting vast amounts of carbon into the atmosphere.
The rapid increase in atmospheric carbon dioxide levels around 40 million years ago approximately coincides with the rise of the Himalayas and may be related to the disappearance of an ocean between India and Asia as a result of plate tectonics – the large scale movements of the Earth’s rocky shell (lithosphere). But, as explained by Professor Paul Pearson of Cardiff University in a perspective article accompanying the Science paper, the hunt is now on to discover the exact cause.
The researchers are Peter Bijl, Alexander Houben, Appy Sluijs, Henk Brinkhuis, Gert-Jan Reichart (Utrecht University), Jaap Sinninghe Damsté and Stefan Schouten (NIOZ Royal Netherlands Institute of Sea Research) and Steven Bohaty (SOES). The research was funded by the Netherlands Organization for Scientific Research Utrecht University and Statoil, and used samples and data provided by the Ocean Drilling Program (ODP).
Publication: Bijl, P. K., Houben, A. J. P., Schouten, S., Bohaty, S. M., Sluijs, A., Reichart, G-J., Sinninghe Damsté, J. S. & Brinkhuis, H. Transient middle Eocene atmospheric CO2 and temperature variations. Science 330, 819 – 8215 (2010).
DOI: 10.1126/science.1193654
http://www.sciencemag.org/cgi/content/full/330/6005/819
Science Perspective:
Pearson, P. N. Increased atmospheric CO2 during the middle Eocene. Science 330, 763-764 (2010). DOI: 10.1126/science.1197894
http://www.sciencemag.org/cgi/content/short/330/6005/763
h/t Dr. Leif Svalgaard
“Bob of Castlemaine says:
November 11, 2010 at 3:54 am”
Defects are appearing in regions not affected by this ash cloud, and if it were as a result of the ash, ALL engines would experience the same, or at least similar “damage”. So far that is not the case. In this case, it is just one engine. But, yes, still, the most tested engine ever made for commercial aircraft, fails in this way. What I’ve seen suggests cracks in engine components not detected.
“Understanding the relationship between the Earth’s climate and atmospheric carbon dioxide in the geological past can provide insight into the extent of future global warming expected to result from carbon dioxide emission caused by the activities of humans,” said Dr Steven Bohaty of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre in Southampton.
Why do we fund and then have to listen to the ramblings of people educated beyond their capacity for comprehension?
The whole lot of them should be put on a train for a field exercise at Aviemore to consider and explain a climatic phenomenon that, contrary to their past prognostications, is becoming a regular, yet unpredicted, occurance.
See here :- http://www.cairngormmountain.co.uk/
They could then be retrained for more useful employment – perhaps as snow plough drivers…….
Hey – please stop criticising this important new scientific finding.
It must be a scientific finding, mustn’t it?
After all, it’s printed in Science!
OR have I got that wrong somehow?
/sarc off
Jimbo, I was just thinking the same: even if the temperature rise was cause by co2, there was no doomsday like Hansen or Tamino and his disciples want us to believe in. Quite the contrary: 5 million years later, Antarctica got it’s permanent ice sheet.
Peter Bijl of Utrecht University. “Such a large change in carbon dioxide certainly provides a plausible explanation for the changes in Earth’s temperature.”
+++++++++++
Remember Trickie Dickie? Plausible deniability?
This stuff is 1/NIXON: Changing Temperatures = Plausible Attributability to CO2
And we have to erase at least 20 minutes of the ice cores.
There was a couple of a warm spikes at about 39.5 Mya and 42.0 Mya but I would put no stock at all in the CO2 estimates from this study.
One of the CO2 estimates is 6,918 ppm (ranging from 5,560 to 8,250).
That is just so far off the charts of where CO2 was at the time and other estimates (1,400 ppm), that it should just be thrown out. If 3.0C per doubling was correct, temperatures should have been 13.0C higher than today when it was only a few degrees higher.
They are using a method which measures Carbon levels and different Carbon isotopes in fossil organic material and this general methodology produces wild swings in estimates including many Zeros. It is just not reliable and shouldn’t be used anymore.
—————————-
There was a new study published in Nature on Oct, 21, 2010 which used high resolution temperature and CO2 estimates right at the Paleocene Eocene Thermal Maximum (PETM) event – 55.8Mya.
The study found that there was a spike in temperatures (55.81 Mya) which occurred before the CO2 increased (55.76 Mya). There might have been two pulses of warming before the CO2 spiked. Temps increased between 4C to 5C in the spike (and CO2 increased from 900 ppm to 1700 ppm in the spike noted from other sources versus this study).
So again we have Temperatures leading CO2 (in a major warming event that has particular fascination for the pro-AGW set).
http://www.nature.com/nature/journal/v467/n7318/full/nature09441.html
How could a mere doubling of co2 cause 4 to 6 degree increase in temperature? And that apparently took 400,000 years. Why are not current temperatures off the charts now considering our rapid increase in atmospheric co2? Does this means we have 300,000 years to reduce our carbon footprint? if so maybe our agw friends could relax and take it easy for a while.
Moebius says:
November 11, 2010 at 1:31 am
It´s disapointing… They so sure to point out CO2, watching their graph, im not so too see a cause-effect relationship in that way… But it’s curious the earth had over 4000 ppm of CO 2 and we are still alive…
Well, it seems reasonable that cells developed at high concentrations of CO2: our lungs work with thousands of ppm, in the alveoli. Respiration is a complicated system that depends on these high values.
There used to be a nice article in wikipedia but I can no longer find it by googling.
Middle Eocene Climate Optimum …… Why do they continue to refer to the warm period as “climate optimum”? Freudian slip or Orwellian oversight?
Probably, the warmer earth held a larger biomass, could that account for the extra CO2?
Seems like we should try natural explanations before we introduce unknown mechanisms. There are already to many mysterious unknowns in climate science.
I don’t get it:
“one of the hottest episodes of Earth’s climate history – the Middle Eocene Climatic Optimum”
A period when the climate is hot, very hot, and atmospheric CO2 is high, very high.
A situation we are told is bad, and we should avoid.
Don’t these people mean to say “The Middle Eocene Climatic Pessimum“?
Just posing – so maybe the temperatures increased, enhancing the quantity of plant life forms and the resulting increase in vegetation caused a significant increase in CO2? Where else could the CO2 come from? Man Bear Pig?
Hmm, seems devoid of science from the original news release. They seem to have started with their conclusion then worked the experiments and analyzed the results to ensure the outcome. As stated above, disappointing.
Anyone buying the article and posting a summary with a little more depth and the quantitative results?
It seems from a quick run through available sources (superficial, like wiki, and things I can recall quickly), the CO2 levels were between two and three times our current levels in the MECO. I cannot find evidence of a change from 800 to 1600 ppm (or other ranges). It seems the trend was a gradual reduction in CO2 from near 1000 ppm with a bump, but a small bump, not a doubling, which should be obvious. Perhaps these researchers will show sufficient rigger to establish a new understanding.
Still, a doubling at that level could not, according to the warmist theories, produce five degrees C warming. And, as has been stated, there is likely a few hundred year lag between warming and CO2 in either direction, so resolution is certainly deficient that far back.
I hope the effort is to increase resolution and understanding, but I fear the only goal is additional grant funding on the CAGW gravy train.
If I may remind, the very warm early Eocene gave rise to the primates and ungulates. No one is yet predicting we will get that warm again. It seems obvious we can handle much warmer temperatures as a planet and as a species.
And just because I like the quote so much:
http://www.scotese.com/climate.htm
I will state again what I have said many times before: its time to institute a review and recall program for PhD degrees, just like occurs for things like medical and engineering certificates.
No scientist can dispute the fact that CO2 gas is released from the oceans when these warm up, (except, of course those of the warmist type). But having said that, I am ready to prove otherwise, that is; the proof that the release of CO2 from the oceans causes global warming. This will be submitted upon confirmation of that still-pending million-dollar grant that I have been begging for for the last years.
………
From Wikedpedia:
“Flora
At the beginning of the Eocene, the high temperatures and warm oceans created a moist, balmy environment, with forests spreading throughout the Earth from pole to pole. Apart from the driest deserts, Earth must have been entirely covered in forests.”
mmm. Not actually bad. All those forests and rich vegetation…. It’s not what AlGore preaches/prophecies in his convenient lie, sorry, i mean “Inconvenient Truth” which is a lie anyway you look at it.
……….
One more shot: With all those big veggie-munching beasts roaming the eocene planet from pole to pole, the methane they produced must have hockey-sticked the eocene warming by some more degrees; like in: Kill all those cows and cattle because their methane-farting activitiies will cause global warming and destroy the planet. But I think the greenies have now actually grown out of that one too, but, come to think of it, i did not see it mentioned in their admission “Where we (greenies) went wrong” of a week or two ago.
Oh how I will miss all this fun when the AGW fable is past its sell-by date, buried and forgotten? I think I will have to take up fishing
Before I get beat up for my last statement, I know that plants take in CO2 and animals exhale CO2. Just didn’t get my coffee this morning. Sorry.
If CO2 can only absorb specific bands of IR energy how come this energy is available through the whole depth of the atmosphere? The way I see it is a fixed amount of energy is absorbed and heats the air. This is a constant. Increasing CO2 simply reduces the level of complete absorption.
Bob of Castlemaine says:
November 11, 2010 at 2:30 am
“The change in carbon dioxide 40 million years ago was too large to have been the result of temperature change and associated feedbacks,” said co-lead author Peter Bijl of Utrecht University. “Such a large change in carbon dioxide certainly provides a plausible explanation for the changes in Earth’s temperature.”
The researchers point out that the large increase in atmospheric carbon dioxide indicated by their analysis would have required a natural carbon source capable of injecting vast amounts of carbon into the atmosphere.
Too large? What about the volcanism associated with tectonics? Forgive me but is it not plausible that the vast amounts of CO2 postulated could have derived from the magma?
Try reading what they say and explain how vulcanism is a “result of temperature change and associated feedbacks”.
Anyone notice that the stated 4 – 6°C temperature increase is conveniently at the top end of the IPCC models
predictionsprojections?I say this is just a sad attempt to prop up a flagging
power grabhypothesis.DaveE.
I posted the suggestion that a (much) larger total biomass would (through decomposing process) release carbon dioxide. It should also be noted that a warmer climate of course increases the speed of the decomposition.
How do one calculate the effects on atmospheric co2 from a rotting green planet?
Is it difficult or already done?
Another two cents on this topic. There is only one time in the last 700 million years where the temperatures and the CO2 levels have been as low as they are now. That was the ice age from the middle-late Pennsylvanian to early Permian periods where the average global temperature was about 12 C and the CO2 was about 350ppm. The GEOCARB III project has the details.
http://www.geocraft.com/WVFossils/Carboniferous_climate.html
I noticed the same thing as M.E. Smith. The methane hydrates would have evaporated as well which would have increase greenhouse gas heat trapping. And, of course, there’s the evaporation of mass amounts of water. If there was tectonic heat events that affected the Indian/Asian ocean, that would have also put a lot more water (and other particulate matter, which suggests cloud formation) into the air. Depending upon the timescale of the ocean event, we could be looking at a system that would provide a lot of trapped heat to the atmosphere.
There’s a lot of missing information here.
Here is my collation of temperature and CO2 estimates over the last 45 Mys.
All CO2 estimates available in the literature (3100 individual estimates charted at 3.0C per doubling so that they are comparable to the temperature estimates) are included in here. I’ve excluded the ones done through the Carbonate method that this paper used – the Carbonate estimates are all over the map and I would have to extend the y-axis to +15C and -15C to include them all, it is just a bunch of random up and down spikes – Berner’s GeoCarb III is not included as well because it is just low resolution every 10 million years and is better for the far distant past where there are fewer estimates available than for the more recent period).
Correlation is very poor. One can also see that cherrypicking a short period with a short CO2 spike gives a very incomplete view of the picture and allows one to make all kinds of exagerrated claims. I think the warming event they are talking about in this paper actually happened at 42 Mya so there might be a problem as well with the dating.
http://img232.imageshack.us/img232/8831/co2sensitivity45m.png
Some of the geographic changes over the last 45 Mys are more relevant to the temperature history in my opinion.
http://img837.imageshack.us/img837/695/tempgeog45m.png
[snip]
Seems to me the increase in CO2 is easily explained. The Tethys Sea would have been like other seas that are getting squeezed. They have a lot of limestone deposites (carbonate rock) from marine life. That in turn would have had a substantial portion of it subducted back to the mantle, melted and ejected as water and CO2.