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
It makes sense to me that if you have warming you also have explosions in animal/insect populations, therefore rises in CO2. And that would be a lag from the temp increasing.
eadler said:
“The sea does does dissolve CO2 and some remains in solution in the liquid. This is not the only possible source of CO2 as you claim. Over a period of 400,000 years, an increase in volcanic activity could result in the increase in CO2 that was observed”
I made no such claim, merely pointed out the implications of the close correlation that they observed between SSTs and CO2 levels.
If a significant portion of that rise in CO2 had been from a volcanic source then the correlation with SSTs would not have been so good would it ?
*******
Article says:
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.
*******
And that’s supposed to be impressive?
You only have to look back 15k yrs or so to see similar changes — 180 to 280 ppm during a 8-10C warmup over a mere few thousand yrs. And the CO2 rise at that time is well demonstrated by the ice-cores to be due to outgassing from warmer oceans, not the cause of the warmer oceans. And this has happened again and again during the last 2 million yrs. Wow, I’m really scared. 🙂
E.M.Smith says:
November 11, 2010 at 1:50 am
The sea floor is lifted over a very large area and turned into mountains. Yet nothing could account for the rise of CO2. OK, how about 2 simple possibles:
1) All that crustal movement lets volcanoes dump a load.
2) If that sea floor had methane clathrate (as we find all over the world now) there would be one heck of a load of outgassing when it was lifted and dried… then oxidized.
I think they need to learn to never say never…
And I think you need to read the paper before making such comments!
As the market collapses the call goes out, cash out now. Or publish now cause you will face real scrutiny next publishing cycle. The desperation and psuedo science of the article is of the standard I have come to perceive as normal for this journal, which I do not purchase anymore.
The 600 to 1000 year lag between T and CO2 may simply be an artifact of how atmospheric gasses get trapped in ice.
Gas in ice at the poles is not instantaneously trapped. It occupies the space between snowflakes and ice crystals as the snow accumulates and, as it is buried, gets compressed and recrystallizes. During this process atmosphere and buried gasses continue to interact. If the composition of the atmosphere changes, so will the as yet un-trapped gases change.
In addition to the above there is reasonable conjecture that diffusion of gases between trapped bubbles and the atmosphere (and other bubbles) occurs, and there is also the issue of different gases diffusing at different rates.
The faith that both sides of the AGW debate place on composition of ice trapped atmospheric gases is misplaced. Too many assumptions are made regarding the timing of concentrations.
Red
November 11, 2010 at 2:36 am
If two substances with different specific heats are subjected to the same energy input, the one with a lower specific heat will increase temperature more.
CO2 has a specifc heat of 0.844 kJ/kgK. 0.844 kJ of added energy will increase the temperature of 1 kg of CO2 by 1K.
N2 has a specific heat of 1.04 kJ/kgK. 0.844 kJ of added energy will increase the temperature of 1kg of N2 by 0.88K.
In isolation (i.e. out of context) your point would be valid. But in the context of adding CO2 to the atmosphere (99% O2 and N2) the substance with the lowest specific heat capacity will have a cooling effect as it will have to emit sooner to achieve equilibrium.
I don’t know about the world of “post normal science” but in the real world, that process is called cooling not warming. Perhaps if you care to notice the specific heat capacity of water vapour you will see that by your own definition, your point is invalid. In the context of the atmosphere, water vapour is the main so called “greenhouse gas” yet has the higher specific heat capacity compared to CO2, O2 and N2.
Mark
November 11, 2010 at 3:26 am
A lower heat capacity simply means you will obtain equilibrium more quickly. If your theory was correct, then the upper ocean would always be much cooler than the atmosphere, because it has a higher heat capacity. This isn’t true.
It depends which part of the atmosphere you are referring to doesn’t it?
Unless you live near the one of the poles, I think you will find that at most places on Earth the ocean IS cooler than the air directly above. Which is why most people experience a cooling off when they take a dip rather than a warming.
Not only is most of the ocean much cooler than the (lower) atmosphere above it, but strangely, (and in contravention to the fallacious bottom up warming of the so called “greenhouse effect” hypothesis) so too is most of the Earths surface, most of the time.
Funny that!
“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.”
Not happening. Any warming would simply increase convection and lead to more efficient heat loss. We do not live in a greenhouse and their picayune view of climate and their singleminded assumptions WILL ALWAYS make them draw the wrong conclusion.
The answer to the question:
“Ancient global warming: but which came first, the temperature or the CO2?”
depends on which warming event is being studied.
This study focused on a period 40 million years ago, and indicated that the release of CO2 caused the warming. For other periods, studies indicate that initial warming caused a release of CO2 stored in ocean waters that boosted the initial warming effect.
While a massive release of CO2 by volcanic action can cause an ice age to end, this is not the only manner for releasing CO2. Another manner is for an initial warming of ocean waters to cause the release of CO2 held by the oceans which added a positive feedback loop to the warming that ends an ice age.
In 2007 the IPCC noted that temperature increases ocurred prior to increases in CO2. http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-6-1.html
Regardless of which came first, increasing CO2 levels results in higher temperatures than would otherwise exist due to the increase in radiative forcing from the additional CO2.
In a previous post on this site described a study whch identified the antarctic as the source of increase in atmosphere CO2 that occurred after a temperaure increase.
http://wattsupwiththat.com/2010/10/25/antarctic-ocean-the-big-kahuna-of-glacial-period-carbon-sinks/
“Scientists know that during the transition from the last glacial period to the current inter-glacial period about 14,000 years ago, carbon dioxide levels rose very quickly at the same time that the age of the carbon dioxide in the atmosphere fell, as measured by radiocarbon data. That suggests carbon dioxide had been stored in the ocean and suddenly released, she said.
One idea holds that it was building up in the Southern Ocean around Antarctica, where extensive sea ice on the surface of the ocean initially prevented the exchange of gasses into the atmosphere, Martin said.”
As Anthony Watts has previously stated:
“any kid in high school chemistry class knows about the solubility of CO2 in water,” which decreases as the temperature of the water increases.
http://wattsupwiththat.files.wordpress.com/2007/11/co2-h2o_solubility.png
A May 2010 study, described below, previously identified the southern ocean as a major carbon sink that is capable of producing a “burp” of CO2 into the atmosphere and noted that the initial warming of the ocean was followed by this “burp”.
Skinner, L.C., Fallon, S. Waelbroeck, C., Michel, E. and Barker S., ‘Ventilation of the deep Southern Ocean and deglacial CO2 rise’ is published in Science on 27 May 2010.
Scientists Detect Huge Carbon ‘Burp’ That Helped End Last Ice Age
http://www.sciencedaily.com/releases/2010/05/100527141959.htm
Excerpt:
ScienceDaily (May 28, 2010) — Scientists have found the possible source of a huge carbon dioxide ‘burp’ that happened some 18,000 years ago and which helped to end the last ice age.
The results provide the first concrete evidence that carbon dioxide (CO2) was more efficiently locked away in the deep ocean during the last ice age, turning the deep sea into a more ‘stagnant’ carbon repository — something scientists have long suspected but lacked data to support.
According to Dr Skinner: “Our results show that during the last ice age, around 20,000 years ago, carbon dioxide dissolved in the deep water circulating around Antarctica was locked away for much longer than today. If enough of the deep ocean behaved in the same way, this could help to explain how ocean mixing processes lock up more carbon dioxide during glacial periods.”
But changes in Earth’s orbit could only have acted as the ‘pace-maker of the ice ages’ with help from large, positive feedbacks that turned this solar ‘nudge’ into a significant global energy imbalance.
Changes in atmospheric CO2 were one of the most important of these positive feedbacks, but what drove these changes in CO2 has remained uncertain.
Scientists think more CO2 was locked up in the deep ocean during ice ages, and that pulses or ‘burps’ of CO2 from the deep Southern Ocean helped trigger a global thaw every 100,000 years or so. The size of these pulses was roughly equivalent to the change in CO2 experienced since the start of the industrial revolution.
If this theory is correct, we would expect to see large transfers of carbon from the ocean to the atmosphere at the end of each ice age. ”
Oddly, just yesterday I read a notice of a study about the end of the more-recent last great ice age which postulated that when sea ice in the Antarctic melted the [uncovered and warming] seas released vast amounts of previously trapped CO2, explaining how the global CO2 levels of the time could have shot up so rapidly while warming continued at a steady [if still “alarmong”, to cold-adapted organisms] pace.
“Which is why most people experience a cooling off when they take a dip rather than a warming.”
Actually,that is because entering water of the same temperature as the air above it cools the body (assuming both air and water are at lower than body temperature) much faster than does the air because the density of water and its heat carrying capacity cause it to extract heat from one’s body much faster than does air.
Air directly above and in contact with water quickly adopts the temperature of the water for the same reason.
On average taking the entire globe the areas where oceans are cooler than the air above and areas where oceans are warmer than the air above are about equal over time but with swings above and below the average due to interacting variations in both air and oceans.
The greenhouse hypothesis doesn’t propose bottom up warming. It proposes additional downward IR warming the surface in the course of delaying the exit of the same energy to space.
However the inability of IR to warm a body of water (as opposed to just a few surface molecules that promptly evaporate) combined with the oceanic control of surface air temperatures means that the extra IR cannot alter the equilibrium temperature of the system as a whole. Instead it just accelerates the hydrological cycle a miniscule unmeasurable amount and the extra energy from that extra downwards IR just vanishes into latent heat and is whisked away by wind and convection for a faster exit to space.
Thus there is an equal and opposite effect that cancels the assumed extra warming from more CO2.
As someone here keeps saying, IT’S THE WATER.
There are many excellent plausible posts here by us, “deniers”. However, the real answer is still that no one knows. But in our favor, at least we “deniers” are not attempting to change public policy, spray SO2 into the atmosphere, cripple the economy, or create a system by which we can make money off of the fears of the public based upon our unproven hypotheses.
This study must be from the same folks who paint dinosaurs in different colors but never tell us they are just “painting” out of their ass. What they say, “Sure dinos existed.” What they say in their emails to each other, “But we don’t really know what color they were.”
What the authors write in the paper, “Sure CO2 existed.” What they email to each other, “But we are just “guessing” out of our ass as to why it rose and fell.”
Stephen Wilde
November 11, 2010 at 12:23 pm
Regardless of the hairsplitting and goal-poast moving, the question is, what is the origin of the “downwelling” IR?
As I have shown on my website with a simple reproducible experiment, it is certainly not CO2.
http://www.theatlantic.com/magazine/archive/2010/12/dirty-coal-clean-future/8307
I am reading this article now and apologize if someone else has posted it. There is this reference which caught my attention: “Now the carbon-dioxide concentration is at or above 390 ppm, which is probably the highest level in many millions of years. “We know that the last time CO2 was sustained at this level, much of the Greenland and West Antarctic ice sheets were not there,” Michael Mann, a climate scientist at Penn State, told me.”
Stephen Wilde
November 11, 2010 at 12:23 pm
I don’t wish to split hairs but this sentence:
“On average taking the entire globe the areas where oceans are cooler than the air above and areas where oceans are warmer than the air above are about equal over time but with swings above and below the average due to interacting variations in both air and oceans.”
contradicts your previous sentence:
“Air directly above and in contact with water quickly adopts the temperature of the water for the same reason.”
Which maybe true for the first few millimetres of air above water. But beyond that we are merely making assumptions.
One more point about the so called “greenhouse effect” hypothesis:
“The greenhouse hypothesis doesn’t propose bottom up warming. It proposes additional downward IR warming the surface in the course of delaying the exit of the same energy to space.”
So according to this hypothesis the surface heats air which heats the surface, right?
In violation of all known laws of thermodynamics.
Add another geologists opinion …mentioned earlier with respect to dating resolution ……
the paper is CRAP!!!!!
So essentially the temperature has gone up and down like it frakking please with no regard, what so ever, for poor massmurdering-dangerous-molecule CO2. Pfft, cheeky bastard.
Interesting period of time in the not so distant geologic past.
There was an active series of super volcanic eruptions in central North America from 44-2 MY ago. The largest was a nearly VEI9 eruption from La Garita caldera in Colorado around 28 MY ago. It left the Fish Canyon tuff, erupting over 5,000 cubic KM of stuff in a single eruption (Yellowstone x3). There is also a minor extinction event 34 MY ago. Multiple large impacts around 35 MY ago (Chesapeake Bay, Tom’s Canyon, Siberia, 2 in Australia, and a few others). Most notably, the global climate gets cooler in the mid-30s MY ago.
I think these clowns are observing natural catastrophic changes in worldwide climate and ascribing those changes to their favorite boogeyman – manmade global warming. This is a shame, as the middle Eocene had a LOT of catastrophic stuff going on, yet no significant extinction event. Has life become more robust since the K-T boundary event? Perhaps, as the Chesapeake event (85 km wide crater), Tom’s Canyon (NJ) event (20 KM), Siberia (5 KM, 20 KM, 100 KM), Australia (8KM, 10 KM, 5 KM), Canada (8KM, 28 KM), did not annihilate life worldwide.
There were lot of impacts in the vicinity of 35 MY ago, as there are a lot of craters on the land. Comet shower? Perhaps. Single body that fragmented and impacted on a regular basis over a few MY? Maybe. But we don’t know yet. You also had an ongoing series of supervolcanic events in North America during the period. Somewhere during the festivities, the climate changed from toasty warm with high CO2 to cold and ice ages (like present) with relatively low CO2, and these clowns blame it all on CO2????
I think they are like the parable of the blind men and the elephant – only able to see what they want to see.
Something (or a lot of somethings) happened in the mid-Eocene (35 MY or so ago) that changed the global climate but did not kill off significant number of species. It was a significant series of events that may or may not be directly related. Yet things on this planet measurably changed. Perhaps they ought to spend more time piecing together what happened in the mid-Eocene than trying to squeeze blood out of the manmade global warming turnip.
No comments in the paper on the use of species that are supposed to be unable to withstand high levels of CO2 as proxies to prove high levels of CO2 causes warming? Did anyone read the paper? What is the PH of their assumed growth environment for the species and how does that affect the conclusion of the paper? Is the idea of acidification incorrect?
Will says:
November 11, 2010 at 2:30 pm
So according to this hypothesis the surface heats air which heats the surface, right?
In violation of all known laws of thermodynamics.
Care to tell us how the laws of thermodynamics are violated by this?
Philip Finck says:
November 11, 2010 at 3:12 pm
Add another geologists opinion …mentioned earlier with respect to dating resolution ……
the paper is CRAP!!!!!
So unlike most on here you’ve actually read it, care to enlighten us with a more substantive comment?
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.
Thanks for being so considerate. God Bless you every one. But we would rather have data.
I think it was clear that the relationship was that warmth causes CO2, that is otherwise dissolved, to rise from the oceans. So Co2 does not cause warming, warming causes more CO2.