From the UNIVERSITY OF COPENHAGEN – NIELS BOHR INSTITUTE and the “worse than we thought” department comes this claim by one researcher looking at the past climate events, specifically the PETM, and using it to predict the future. It is unclear what caused the PETM, scientists can only speculate with ideas like the methane burp hypothesis. He’s right about future warming depending on “the sensitivity of the climate system and response to feedback mechanisms”, but so far climate sensitivity seems to be lower than predicted, and positive feedbacks don’t seem to be manifesting themselves in the atmosphere.
Warning from the past: Future global warming could be even warmer
Future global warming will not only depend on the amount of emissions from man-made greenhouse gasses, but will also depend on the sensitivity of the climate system and response to feedback mechanisms. By reconstructing past global warming and the carbon cycle on Earth 56 million years ago, researchers from the Niels Bohr Institute among others have used computer modelling to estimate the potential perspective for future global warming, which could be even warmer than previously thought. The results are published in the scientific journal,Geophysical Research Letters.
Global warming from greenhouse gas emissions depends not only on the size of the emissions, but also on the warming effect that the extra amount of gas has on the atmosphere. This effect, called climate sensitivity, is usually defined as the warming caused by the doubling of the amount of CO2 in the atmosphere. Climate sensitivity depends on a number of properties of the earth’s climate system, such as the composition of clouds and cloud cover.
“The research shows that climate sensitivity was higher during the past global, warm climate than in the current climate. This is bad news for humanity as greater climate sensitivity from warming will further amplify the warming,” says Professor Gary Shaffer, University of Magallanes, Chile, and the Niels Bohr Institute, University of Copenhagen.
The past tells about the future
The study was based on reconstructions and climate modelling of a period of global warming 56 million years ago. The period known as the Palaeocene-Eocene Thermal Maximum (PETM) was triggered by massive releases of carbon into the atmosphere and climate researchers have long identified it as a time that could in some ways be analogous to today’s global warming.
Reconstructions of past temperatures show that even before the PETM the Earth was about 10 degrees warmer than today and then warmed an additional 5 degrees during the PETM. In addition, they combined data about minerals, isotopes and the carbon cycle with climate models to estimate the concentration of CO2 in the atmosphere – both before and during the period. From this, they could estimate the climate sensitivity and the result was that where it was about 4.5 degrees C before the PETM, the temperature rose to about 5.1 degrees during the PETM. Climate sensitivity is currently around 3 degrees.
“Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current ‘easily accessible’ fossil fuel reserves of about 4,000 billion tons. But the warming that would result from adding such large amounts of carbon to the climate system would be much greater today than during the PETM and could reach up to 10 degrees. This is partly due to the current atmosphere containing much less CO2 – approximately 400 ppm (parts per million) – compared to before the PETM, where the concentration was about 1,000 ppm and partly because we emit carbon into the atmosphere at a much faster rate than during the PETM. If we then also take into account the fact that climate sensitivity increases with the temperature, it means that it is all the more urgent to limit global warming as soon as possible by reducing the man-made emissions of greenhouse gases,” explains Professor Gary Shaffer, who conducted the study in collaboration with researchers from Purdue University, USA, the University of Chile and the Technical University of Denmark.
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So we are doomed, after all.
Yeah, shuffle Antartica a few thousand kilometers northward, unslam the Indian sub-continent and unfold the Himalyan rocks that pushed land masses near-into the tropopause… then close the Atlantic a few 1000 km, and open Panama as a straight.
That should just about get the continents back to the PETM config.
After that, devolve C4 plants and grasses.
According to Sluijs, et al., Nature (December 2007) [1]:
“We show that the onsets of environmental change (as recorded by the abundant occurrence (‘acme’) of the dinoflagellate cyst Apectodinium) and of surface-ocean warming (as evidenced by the palaeothermometer TEX86) preceded the light carbon injection by several thousand years.”
English translation:
During PETM, temperature rose 3,000 years before CO2 rose!
Thus, PETM could not have been caused by the CO2 greenhouse effect.
1-“Environmental precursors to rapid light carbon injection at the Palaeocene/Eocene boundary”
– Sluijs, et al., Nature 450, 1218-1221 (20 December 2007)
http://www.nature.com/nature/journal/v450/n7173/full/nature06400.html
Reconstructions seem to have CO2 falling before the PETM (http://www.geocraft.com/WVFossils/CO2_Temp_O2.html). But with the Eco-Naz!s, it’s always cart before the horse even when the temperature and CO2 level are both rising. CO2 doesn’t “drive” ANYTHING.
Oh right. We can tell exactly how/why the climate changed 56 million yrs ago. Of course CO2 was the cause. /sarc
They’ve never been able to show CO2 was the cause of ANY temperature change. It’s pure hypothetical BS. Reality shows that if there IS a relationship, it’s temperature driving CO2 levels (based on solubility of CO2 in water), not the other way around.
The problem with this paper is that there is no way to measure the CO2 concentration during the PETM with any precision. What can be measured precisely is the change of carbon isotope ratios, from which the change in the amount of CO2 in the atmosphere can be estimated provided you know the isotope ratio of the CO2 added to the atmosphere.
Unfortunately this is not known, since the isotope ratio depends on the source of the carbon. At least the following six sources have been suggested for the PETM:
1. Impact of a volatile-rich asteroid (or more likely a comet)
2. Release of methane from deep-sea methane hydrates
3. Very large scale peat fires
4. Oxidation of organics-rich marine deposits in desiccated former shallow seas
5. Oxidation of organics by large scale volcanic eruptions through carbon-rich sedimentary rocks
6. Large-scale melting of permafrost in interior East Antarctica
All of these will give different results, and to complicate things further, combinations of two or more of these mechanisms are quite possible.
Also the best PETM profiles show pretty conclusively that the climate warming started slightly before the isotope ratio change, which suggests that the change in the carbon cycle was a consequence rather than a cause of the warming.
They are dreaming if they rthink that carbon dioxide caused the PETM. It was ten times higher in the Cambrian and Ordovician while temperature then stayed at the Cretaceous level which precedes PETM. What they need is to understand that carbon dioxide is not warming the world now and has not done so in historic times. The most direct observation of this comes from the existence of the twenty-first century hiatus. It so upset the warmists that they sent NOAA out in the hope of unearthing global warming that could prove absence of the hiatus. They did find some questionable data which Karl et al. then blew up and claimed that it proved the non-existence of the hiatus. What happens during a hiatus is that atmospheric carbon dioxide keeps increasing as it has since measurements exist, but temperature does not. If you shorten the global temperature observation period to a segment between 2002 and 2012 you are leaving out the super El Nino of 1998 that is usually included in the hiatus. What you have now is a ten year long temperature segment that is no longer just horizontal but actually slopes down. No way can this be turned into warming as Karl would have it. The Arrhenius greenhouse theory they use requires that if carbon dioxide goes up, temperature also must go up. Existence of a horizontal temperature curve, or even better, one that slopes down, is totally impossible according to their own greenhouse theory. Their theory has made a wrong prediction here and a scientific theory that makes a wrong prediction belongs in the trash can of history. The only greenhouse theory that correctly predicts the hiatus temperature is MGT, the Miskolczi greenhouse theory. According to MGT, carbon dioxide and water vapor in the atmosphere form an optimal absorption window in the infrared whose optical thickness is 1.87. If you now add carbon dioxide to the atmosphere this has the effect of increasing the optical thickness. The added carbon dioxide also causes additional absorption, just as Arrhenius says. But as soon as this happens, water vapor will start to diminish, rain out, and the original optical thickness is restored. The added CO2 will of course keep absorbing beyond that point but by now the removal of water vapor has reduced total absorptivity to background level and no greenhouse warming predicted by the Arrhenius theory is possible. An observer looking from the side sees carbon dioxide increasing but no change in temperature. That is exactly what is happening during the hiatus. But even better, it is not necessary to have a hiatus to stop warming. This process works any time you add carbon dioxide to the atmosphere, hiatus or no hiatus. Hence, greenhouse warming is simply impossible.
Of course they can’t be sure yet they say increased co2 in the atmosphere was what caused the PETM . What else could have caused it other than a trace gas which is present in the atmosphere at 400 parts per million, or less than .05 of one percent.