CO2 drop and global cooling caused Antarctic glacier to form
February 26, 2009
Projection of the what the first Antarctic ice sheet might have looked like as the global climate cooled about 33.5 million years ago. Antarctica is in gray, with the ice sheet shown in meters of ice thickness. The ice sheet is continental in scale, but somewhat smaller than today. The estimate is based on prior modeling work of DeConto and Pollard and is supported by this new data study. Credit: DeConto & Pollard/ Nature
(PhysOrg.com) -- Global climate rapidly shifted from a relatively ice-free world to one with massive ice sheets on Antarctica about 34 million years ago. What happened? What changed? A team of scientists led by Yale geologists offers a new perspective on the nature of changing climatic conditions across this greenhouse-to-icehouse transition—one that refutes earlier theories and has important implications for predicting future climate changes.
Detailed in the February 27 issue of Science, their data disproves a long-held idea that massive ice growth in the Antarctic was accompanied by little to no global temperature change.
This report shows that before the Southern Hemisphere ice expansion, high-latitude temperatures were at least 10°C (about 18˚F) warmer than previously estimated and that there was a 5˚C - 10˚C drop in surface-water temperature during the climate transition.
"Previous reconstructions gave no evidence of high-latitude cooling," according to senior author Mark Pagani, professor of geology and geophysics at Yale. "Our data demonstrate a clear temperature drop in both hemispheres during this time."
Their conclusions are based on sea-surface "temperature proxies" - calculations of temperature based on the distribution of specific organic molecules from ancient plankton that only lived at certain temperatures and were later preserved in ocean sediments. These molecules were assayed in ocean cores collected by the Integrated Ocean Drilling Program (IODP) and earlier marine programs that study Earth history by coring deep-ocean sediments and crust around the world.
"Temperatures in some regions, just before the Antarctic glaciers formed, were surprisingly higher than current climate models predicted, suggesting that these models underestimate high-latitude warming under high CO2 conditions," said lead author Zhonghui Liu, Pagani's postdoctoral associate who is now an assistant professor at the University of Hong Kong. Further, he said, the substantial cooling that occurred in both Northern and Southern high latitudes suggests that a decline in CO2 level, rather than a localized change of ocean circulation drove the climate transition.
The ice formed over Antarctica in about 100,000 years, which is an "overnight" shift in geological terms. "Just over thirty-five million years ago, 'poof,' there was an ice sheet where there had been subtropical temperatures before," said Co-author Matthew Huber of Purdue University.
Another theory refuted by this study is the notion that ice-expansion also occurred in the Northern Hemisphere during this time — a supposition poorly supported by physical evidence of glacier formation in that region, say the Yale scientists.
There are about 70 meters of vertical sea level rise represented in the ice sheets of Antarctica. And, there are many questions regarding the glacier's stability, the temperature thresholds that would cause radical glacier melting, and the rate at which it would change, according to Pagani. "Our findings point to the difficulty of modeling accurate temperatures under higher CO2 in this critical region."
Provided by Yale University
Nov 05, 2009 |
not rated yet |
0
I'll read the article for more details.
Info on CO2 and where it went and why did CO2 vanish OR was it because the temperature dropped that the CO2 vanished and how long after the temperature dropped?
Which ever happened first we could do with some possible causes, and other results. like, what happened to corals and shellfish of the oceans when acidity suddenly reduced or did the acidity change that much and if not why not?
These are just a few of the questions that spring to mind.
And that's the gorilla in the room. CO2 doesn't drive climate but climate drives CO2. Explains the lags in CO2 vs temp, explains the need for excessive proxy correction, explains a lot of the holes in GW. All you have to do is remove the A in AGW and it becomes more sound as a descriptive framework.
Oh, and Nature (magazine) does not "produce" science. It publishes science papers and treatises.
"You obviously have no inkling of science and scientific publishing."
Neither do you.
Peer review comprises of a "review" by recognised sientists who comment on the viability of the science in the paper in their opinion. Mostly reviewed by a person known to them (on their Christmas card list?). A clique (IPCC?) with an agenda can peer review each other. It can work for warmers or sceptics.
Verifying a paper is all together different. Data compiled and methods used are checked carefully.
With some recent papers, such as the Antarctic is warming one, it is proving almost impossible to obtain this data. Steve Macintyre and others are doing such verification were possible are showing glareing errors or complete fabrication in some cases.
BTW. I don't think anyone has yet submitted a paper showing the direct link between man released CO2 and global warming, only computer guesework.
If anyone can find one, please show me.
[http://www.aps.or...ndex.cfm
http://scienceand...ing.html
http://scienceand...ors.html
I'm looking for references that are factual and pro-agw. Hardly surprising that none have appeared as of yet.