Another paper for the Copenhagen train. This is an estimate according to the abstract. Here’s the abstract and the supplemental information, of course the publicly funded paper is behind the AAAS paywall.
From UCLA News: Last time carbon dioxide levels were this high: 15 million years ago, scientists report
By Stuart Wolpert October 08, 2009 Category: Research
You would have to go back at least 15 million years to find carbon dioxide levels on Earth as high as they are today, a UCLA scientist and colleagues report Oct. 8 in the online edition of the journal Science.
“The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels — global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland,” said the paper’s lead author, Aradhna Tripati, a UCLA assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences.
“Carbon dioxide is a potent greenhouse gas, and geological observations that we now have for the last 20 million years lend strong support to the idea that carbon dioxide is an important agent for driving climate change throughout Earth’s history,” she said.
By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth’s atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time. But there has been little agreement before this study on how to reconstruct carbon dioxide levels prior to 800,000 years ago.
Tripati, before joining UCLA’s faculty, was part of a research team at England’s University of Cambridge that developed a new technique to assess carbon dioxide levels in the much more distant past — by studying the ratio of the chemical element boron to calcium in the shells of ancient single-celled marine algae. Tripati has now used this method to determine the amount of carbon dioxide in Earth’s atmosphere as far back as 20 million years ago.
Aradhna Tripati
“We are able, for the first time, to accurately reproduce the ice-core record for the last 800,000 years — the record of atmospheric C02 based on measurements of carbon dioxide in gas bubbles in ice,” Tripati said. “This suggests that the technique we are using is valid.
“We then applied this technique to study the history of carbon dioxide from 800,000 years ago to 20 million years ago,” she said. “We report evidence for a very close coupling between carbon dioxide levels and climate. When there is evidence for the growth of a large ice sheet on Antarctica or on Greenland or the growth of sea ice in the Arctic Ocean, we see evidence for a dramatic change in carbon dioxide levels over the last 20 million years.
“A slightly shocking finding,” Tripati said, “is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”
Levels of carbon dioxide have varied only between 180 and 300 parts per million over the last 800,000 years — until recent decades, said Tripati, who is also a member of UCLA’s Institute of Geophysics and Planetary Physics. It has been known that modern-day levels of carbon dioxide are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new.
Prior to the Industrial Revolution of the late 19th and early 20th centuries, the carbon dioxide level was about 280 parts per million, Tripati said. That figure had changed very little over the previous 1,000 years. But since the Industrial Revolution, the carbon dioxide level has been rising and is likely to soar unless action is taken to reverse the trend, Tripati said.
“During the Middle Miocene (the time period approximately 14 to 20 million years ago), carbon dioxide levels were sustained at about 400 parts per million, which is about where we are today,” Tripati said. “Globally, temperatures were 5 to 10 degrees Fahrenheit warmer, a huge amount.”
Tripati’s new chemical technique has an average uncertainty rate of only 14 parts per million.
“We can now have confidence in making statements about how carbon dioxide has varied throughout history,” Tripati said.
In the last 20 million years, key features of the climate record include the sudden appearance of ice on Antarctica about 14 million years ago and a rise in sea level of approximately 75 to 120 feet.
“We have shown that this dramatic rise in sea level is associated with an increase in carbon dioxide levels of about 100 parts per million, a huge change,” Tripati said. “This record is the first evidence that carbon dioxide may be linked with environmental changes, such as changes in the terrestrial ecosystem, distribution of ice, sea level and monsoon intensity.”
Today, the Arctic Ocean is covered with frozen ice all year long, an ice cap that has been there for about 14 million years.
“Prior to that, there was no permanent sea ice cap in the Arctic,” Tripati said.
Some projections show carbon dioxide levels rising as high as 600 or even 900 parts per million in the next century if no action is taken to reduce carbon dioxide, Tripati said. Such levels may have been reached on Earth 50 million years ago or earlier, said Tripati, who is working to push her data back much farther than 20 million years and to study the last 20 million years in detail.
More than 50 million years ago, there were no ice sheets on Earth, and there were expanded deserts in the subtropics, Tripati noted. The planet was radically different.
Co-authors on the Science paper are Christopher Roberts, a Ph.D. student in the department of Earth sciences at the University of Cambridge, and Robert Eagle, a postdoctoral scholar in the division of geological and planetary sciences at the California Institute of Technology.
The research was funded by UCLA’s Division of Physical Sciences and the United Kingdom’s National Environmental Research Council.
Tripati’s research focuses on the development and application of chemical tools to study climate change throughout history. She studies the evolution of climate and seawater chemistry through time.
“I’m interested in understanding how the carbon cycle and climate have been coupled, and why they have been coupled, over a range of time-scales, from hundreds of years to tens of millions of years,” Tripati said.
In addition to being published on the Science Express website, the paper will be published in the print edition of Science at a later date.
UPDATE: Bill Illis add this graph in comments, which brings up the obvious correlation questions.
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rbateman (11:48:33) :
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Jim (11:23:18) :
I wonder that myself. What C02 sources lie below the ice that can permeate upwards, giving the impression of rising C02 levels the deeper one drills?
If it’s vulcanism, then if one drills an area pattern, a dome of trapped C02 would appear in the results.
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If it does diffuse at all, CO2 has plenty of time to move. It could account for th rather flat concentration. (The handle of the hockey stick).
There are those of us who know that Climate Science has been hijacked by loonies who are at the tops of all the science organizations including the Climate Science department of Wikipedia.
I looked up Dr Robert Balling, said by a 1990 BBC programme (before the new Iron Curtain fell) to be an expert on UHI. Now it looks from his stuff as if he just does his best to stay out of trouble, otherwise he’d be out of academia altogether probably. And just a short Wiki article that’s slander because at least at one time he was an outspoken skeptic and critic.
In mythology the problem of Climate Science is described as the monster the Hydra, with hundreds of heads which all had to be cut off and cauterized, otherwise several more would spring in the place of the old heads. Joanne Rowling has given the Hydra a new lease of understanding with “Horcruxes”. In Climate Science, each Hockey Stick is another head of the Hydra, another Horcrux, IMO. Each one can only be “decapitated and cauterized” by its own specialists.
I still suspect that Jaworowski (if he’s still alive) and Segalstad regard the current CO2 hockey stick as seriously misbegotten. I am still sure that CO2 escapes from the depths of firn by solution and under pressure, and that CO2 levels recorded from deep ice cores are all too low. But on this point I am still no match for Ferdinand Engelbeen, whom I regard with affection and take seriously; he doesn’t think much of Segalstad.
Can anyone help spell out something in layman’s terms? Oh, and I’d like to see other CO2 measurements done at Mauna Loa, if such exist. And why did they choose volcanic outgassing Mauna Loa when non-volcanic islands are available?
Well, well. WRT CO2 diffusion, check this out:
http://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000187/art00012?crawler=true
“This record is the first evidence that carbon dioxide may be linked with environmental changes, such as changes in the terrestrial ecosystem, distribution of ice, sea level and monsoon intensity.”
The only thing this type of study and the associated non-journalism proves is that our schools are failing, including our universities. Sticking with the school theme – Lets examine this statement closely, class. This EVIDENCE MAY be LINKED with environmental changes… If that doesn’t just fill you full of confidence that they are correct, you are just being hard headed. I mean after all, who needs causal evidence when you MAY be able to potentially LINK two things together. And, yes, I know I’m occasionally shouting via text. I’m the last angry hippie and I want the world to know it!
I think Dr. Dean Edell summed up a ‘link’ the best when he said “You can link french fries with car accidents if you want, but you’ll never be able to prove they cause them.”
Shouldn’t the little blue bar identifying the range for the past 800,000 years be lifted to include present day readings. One would assume that the past 800,000 years would include yesterday.
Secondly, the graph shows that we are just barely at the bottom of the range from 15,000,000 years ago. Only with the dramatic IPCC projections does this look remotely alarming. Especially when we know little or nothing about the other factors extant 15 million years ago.
Her choice of 15 million years ago was convenient to prove her hypothesis, why did she not choose 20 or 25 million years ago when the CO2 levels were much higher?
Why is the climate science community so in love with hockey stick graphs?
The most recent 50,000 years of the Vostok graph would produce a hockey stick too.
http://en.wikipedia.org/wiki/File:Vostok-ice-core-petit.png
And its data ends around 1950.
John M Reynolds
Well, I’m not surprised that CO2 is at record levels (so not OT, honest 🙂 I have just been informed that over 40% of CO2 is due to heating houses and driving cars!
This terrifying statistic was delivered in Britain tonight in a national tv ad by ‘Action on CO2’ through the appropriate medium of a fairy story. Those of you that are denied the pleasure of British tv can watch it on their website:
http://www.actoncopenhagen.decc.gov.uk/en/ukaction/government/act-on-c02-ad
Warning – may cause nausea and vomiting!
Seriously though, this looks like a clear breach of advertising regulations – it’s my understanding that total contribution of fossil fuel burning is 3-4% of CO2 generated; presumably they mean 40% of that, but the ad clearly gives a very different and misleading impression.
I’m curious,
That spike about 25 million years ago, what was the ocean content and how much oil would that equate to?
While I am no climate scientist, I have enough background and understanding of geochemistry to know that gas in ice bubbles is not isolated as is apparently assumed by the climate community. CO2 and other gasses trapped in ice crystals diffuses both through the crystal lattice and via crystal boundaries.
I am not aware of any systematic study of the rates of gas diffusion in ice crystals, but they are likely to be significant, particularly when the ice is young. This may explain at least part of the 800 lag, but it also calls into question both the concentrations and isotope ratios of CO2 and other gas inclusions in ice cores.
I don’t think either side of the climate debate has reasonable justification to use the ice core CO2 or 18O ratios to make any definitive statements about atmospheric trace gas concentrations. All they can really say is that cold climate regimes have low CO2 trace concentrations and hot ones have higher ones.
I have a problem with the “CO2 is a potent greenhouse gas” phrase. It really isn’t all that “potent” when you consider the overall mix of gasses in our atmosphere. That is another example of the “conventional wisdom” being passed off as fact.
CO2 is much less “potent” of a greenhouse gas than water vapor is. There is also a natural negative feedback in that if you introduce more CO2, plants absorb more of it through enhanced growth so the more CO2 you put into the atmosphere, the faster it comes out. Also, is that response linear? I don’t know. Maybe if you increase CO2 by 10% you get a 15% increase in plant growth so you end up pulling it back out faster than you are putting it in.
Would a 100% increase in CO2 result in more than a 100% increase in biomass creation? It would be something interesting to find out. One study in 2000 by Duke University found that loblolly pines grown in an ambient atmosphere of CO2 that is 50% above normal ambient were twice as likely to produce cones, produced 300% as many cones and 200% as many seeds per tree in addition to putting on more trunk mass.
The site this appears in does not seem to be a geology site, it is rather a pot pouri site from biology to ….
I will be very surprised if it is peer reviewed. I spent some time on http://www.sciencemag.org/about/ and could find nothing about peer reviewing. Does anybody have a link to the acceptance policy?
In general I am disgusted that this is called science.
C’mon, guys! Give her a break! Haven’t you seen her picture?
If she is discredited we’ll just get more Gavin Schmidt. No one wants that.
“There is nothing “natural” about pumping out CO2 and paving over 25% of the landmass of the planet.”
Go Joni Go!
Please….Not again!
Okay, help me out here. Am I having a senior moment, seriously. I look at the graph and see that CO2 doesn’t cause temperature changes. Am I right…or wrong? Someone, please?
Ice is not in steady state. Gas trapped in ice diffuses over time.
Chemical Physics Letters
Volume 385, Issues 5-6, 16 February 2004, Pages 467-471
Title: Diffusion of nitrogen gas in ice Ih
Abstract
Diffusion of N2 in ice crystal has been found from Raman scattering of the natural ice from the Antarctic ice sheet. In order to investigate the diffusion mechanism, we perform molecular dynamics simulations of diffusion of N2 in ice. The results show that the N2 molecule hops in the crystal by breaking hydrogen bonds in the ice lattice. The diffusion velocity with the mechanism is few orders larger than the estimate under the assumption of the interstitial mechanism. We conclude that the localized vibrational motion of N2 is the dominant factor governing the diffusion mechanism.
and
Journal of Glaciology 2008, vol. 54, no187, pp. 685-695
Title: CO2 diffusion in polar ice : observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core
by
AHN Jinho (1 2) ; HEADLY Melissa (1) ; WAHLEN Martin (1) ; BROOK Edward J. (2) ; MAYEWSKI Paul A. (3) ; TAYLOR Kendrick C. (4) ;
Abstract
One common assumption in interpreting ice-core CO2 records is that diffusion in the ice does not affect the concentration profile. However, this assumption remains untested because the extremely small CO2 diffusion coefficient in ice has not been accurately determined in the laboratory. In this study we take advantage of high levels of CO2 associated with refrozen layers in an ice core from Siple Dome, Antarctica, to study CO2 diffusion rates. We use noble gases (Xe/Ar and Kr/Ar), electrical conductivity and Ca2+ ion concentrations to show that substantial CO2 diffusion may occur in ice on timescales of thousands of years. We estimate the permeation coefficient for CO2 in ice is ∼4 x 10-21 mol m-1 s-1 Pa-1 at -23°C in the top 287m (corresponding to 2.74 kyr). Smoothing of the CO2 record by diffusion at this depth/age is one or two orders of magnitude smaller than the smoothing in the firn. However, simulations for depths of ∼930-950 m (∼60-70 kyr) indicate that smoothing of the CO2 record by diffusion in deep ice is comparable to smoothing in the firn. Other types of diffusion (e.g. via liquid in ice grain boundaries or veins) may also be important but their influence has not been quantified.
Extensive discussion on methodology and problems with CO2 measurements in ice bubbles please refer to Jaworowski et al. 1992 (see link)
And from 1880 to present, a sea level rise of about ten inches is associated with an increase in carbon dioxide levels of about 100 parts per million, i.e. chump change.
75 feet vs. 10 inches? Splain, Lucy!
The only way to determine accurate c02 levels from the past is through interpretation of carbon isotopic ratios in fossilized soils (paleosols) or the shells of phytoplankton and through interpretation of stomatal density in fossil plants.
ice bubble core measurements are only a barometer that show a trend.
http://i38.tinypic.com/mtqoid.jpg
shows c02 over 500 million years. Previous to 15 million years ago, it must have been permanently blisteringly hot. – although there is no correlation between temperature and carbon dioxide in this record.
It leads to the question: Is there in fact a correlation between c02 and temperature at all?
Michael (11:49:56) :
The global cooling news just keeps getting better.
California and Colorado ski resorts in a snow daze
And in NZ, Mt Ruapehu has just announced an extended season.
over longer time scales, palaentology around the world can infer c02 proxies. Using ice is something of a cop out.
by analyzing the ratio of heavier oxygen-18 to ordinary oxygen-16, and heavier deuterium-2 to ordinary hydrogen-1, in the ice.
Still, even taking ice core measurements as reliable, over 420,000 years, temperatures have varied nearly 20F, from about 16F below to 6F above the temperatures of the past century. If CO2 levels today are “unprecedented” and CO2 causes warming, then why are temperatures today lower than at several times in the ice core record of the last 400,000 years?
Jaworowski et al 1992
http://www.co2web.info/np-m-119.pdf
DEPLETION OF CO2 IN SURFACE SNOW (source: http://www.greenworldtrust.org.uk)
An important finding of Raynaud and Delmas (1977) was the observation that in surface firn (up to 1 m depth) at the Pionerskaya and Vostok stations the concentration of CO2 in the interstitial air was 160 to 240 ppm, respectively, whereas at that time in the atmospheric air this concentration was reported to be 310 ppm. This demonstrates that, even in snow that was not subject to longer firnification and firn-ice transition processes, the CO2 content could have been reduced by up to 150 ppm, i.e. about 48% lower than in the ambient air of the same age. This important field experiment was never repeated in the later CO2 studies.
The striking feature of the glacier data used as an evidence for a recent man-made CO2 increase is that all of them are from ice deposited not in the last decades but in the 19th century or earlier. In these studies no information was presented on the recent concentrations of CO2 in firn and ice deposited in the 20th century. The results of CO2 determination in the pre-industrial ice are not compared with the CO2 content in recently deposited snow, firn or ice but with its current levels in the atmosphere. To justify such comparisons an assumption was needed that the entrapment of air in ice is purely a mechanical process, involving no chemical differentiation of gases. However, as appears from the discussion in this report, and as was demonstrated by Jaworowski et al. (1992), this assumption is wrong.
I have been reading her website, it is very impressive, and she has load of papers she has written. And loads of funding.
http://aradhna.tripati.googlepages.com/home
Of paramount importance for understanding climate change is the quantification of past relationships between temperature, sea level, and atmospheric carbon dioxide levels. To date, my research has focused on using used novel approaches to accurately constrain these variables.
My past work in this area (Tripati and Elderfield, G3, 2004) has been cited by the UN-IPCC in their 2007 report on the Scientific Basis for Climate Change.
That must mean she is really good right?
Re: Smokey (11:47:55)
[…Conclusion: they’re lying to us about the effect of CO2, which is a beneficial trace gas that is every bit as essential as H2O to life on Earth…]
Smokey, you are correct. They are either lying, or a bunch of people are all doing the same thing wrong. The GHE doesn’t even work the way that climate alarmists claim. Allow me to explain.
Lets take a look at a radiance plot from one of the stations in the SURFRAD network.
http://www.srrb.noaa.gov/cgi-bin/surf_check?site=desr&mos=June&day=2&year=2008&p1=dpsp&p5=dpir&p6=upir&ptype=gif
This is a plot of the observations of downwelling solar, downwelling IR and upwelling IR during a cloud-free clear-skies day at the Desert Rock, NV SURFRAD station. Do you notice anything odd? I notice that there is no day/night signal in the downwelling IR, even though upwelling IR increases up to 200 W/m^2, a 50% increase during daylight hours. How can that be? If the GHE worked the way the alarmists claimed (atmospheric GHG’s absorb upwelling IR and re-radiate half back towards the surface) there would have to be a day/night signal in the downwelling IR, but…there is none. That is because the GHE doesn’t work the way they claim.
Heinz Hug is correct. No tropospheric gas emits energy due to radiative decay, because the rate of collisional de-excitation is much more rapid than the radiative decay rate. In other words, IR-absorbing gas molecules lose any energy they gain to molecular collision, or conduction, to the surrounding gas molecules (~97% of which is O2 and N2) before they ever get a chance to radiate any of it. Convection and adiabatic cooling further serve to prevent radiative decay as the atmosphere loses KE as it rises.
Well then, if that’s true, where does the downwelling IR come from? All of the IR that downwells from the troposphere to the surface is the latent energies of condensation and fusion released by water vapor as it changes phase at altitude in the atmosphere (with half of those energies having been emitted upwards, of course). These are processes that are unaffected by the day/night cycle and explain why there is no day/night signal in the downwelling IR.
There is also a small amount of downwelling IR received at the surface due to stratospheric ozone because ozone radiates at wavelengths (wavenumber (^-cm) 1000-1100) that the troposphere is mostly transparent to, but it is very minor in comparison. (Stratospheric atmosphere densities are too sparse, and collisional de-excitation rates are too slow to prevent radiative decay).
Take a look at figure 1 in this paper.
http://esto.nasa.gov/conferences/estc-2002/Papers/B4P2%28Mlynczak%29.pdf
This is a color diagram depicting cooling (due to radiation) in the atmosphere from the surface to 100 mB across the IR spectrum of wavenumber (cm^-1) 0 to 2500. As the authors state: “This figure clearly illustrates that far-infrared emission by water vapor is responsible for cooling the atmosphere from the surface to around 200 mb. The bulk of the free troposphere cools radiatively in the far-IR portion of the spectrum.” The authors did not point out (and I don’t blame them, they do work for NASA, job security and all that) but I will, the lack of cooling (radiation) between wavenumbers (^-cm) 600 to 700, where CO2 is active. In fact there is no cooling (radiation) in the troposphere that can be attributed to anything but water vapor. Only water vapor radiates in the troposphere.
I would also like to point out in figure 1 the strongest cooling seen at ~300 mB. As water vapor rises through the atmosphere, if it fails to condense or encounter a nucleation seed, as it passes ~700 mB (where a temperature of 0C is generally encountered) it continues to rise as supercooled water vapor. Upon reaching ~300mB, where the temperature is ~ -40C, the water vapor undergoes spontaneous crystallization due to crystal homogeneous nucleation, releasing both of the latent energies of condensation and fusion all at once. This, together with the shift of the peak of the Plank function described by the authors is why the cooling signal is so strong there.
Well, there you have it. CO2 and some of the other trace gases in the atmosphere do absorb IR, they just don’t radiate any of it in the troposphere. Those trace gases have no effect on surface temperatures. The overall calculated average annual planetary surface temperature may have risen a bit in the last one hundred years or so, but it did not have anything to do with CO2, or any other trace gas.
AGW is pure bunk.
And after all of that, multiple ice ages still occurred AFTER the CO2 was “sustained at levels of today.”
Sounds like a self-regulating system to me. No runaway warming. No irreversible catastrophe.
Is this a “proxy” for temperatures? Should we place the same “faith” that she got it right, as did Briffa and his beloved tree-rings? Is the raw data available for scrutiny? Are there outliers that should be excluded but were not? Does the other data that indicates ancient temperature support these conclusions?
O. Weinzierl (10:40:25) :
So what? For me as a geologist 15 mil years is not so long ago. I find it much more frightening that just recently / 10.000 years ago there was an Ice age.
I am also a Geologist and even more frightening is the Four KNOWN Glaciations and Interglacials in the Pleistocene. Pray tell what caused THOSE temperature variations?
Someone needs to invite Aradhna Tripati over here to answer a few questions.