http://www.digitaljournal.com/article/279245

Antarctic ice cap will be gone if we don't reduce greenhouse gas Special

Posted Sep 15, 2009 by Stephanie Dearing
A new finding by a research team links atmospheric levels of carbon dioxide to the formation of the Antarctic Ice Cap. The authors say that unless serious cuts to emissions are made, global warming will ensure the loss of the ice cap.
Antarctica
Antarctica: The blue ice covering Lake Fryxell, in the Transantarctic Mountains, comes from glacial meltwater from the Canada Glacier and other smaller glaciers. The freshwater stays on top of the lake and freezes, sealing in briny water below.
Photo by Joe Mastroianni, National Science Foundation
The research team is composed of three people from the United States and the United Kingdom, representing three different universities.
The researchers were examining ancient rocks in Tanzania, looking for evidence of carbon dioxide levels 34 million years ago. This point in time is known as the Eocene-Oligocene Climate Transition, a time when carbon dioxide levels in the world fell and the Antarctic ice caps formed. The evidence of a decrease in the amount of carbon dioxide in the air at this time gives credence to climate change theories. The team based their findings on results obtained from microfossils they found in Africa. Researcher Professor Paul Pearson explained why to Reuters saying "There are no samples of air from that age that we can measure, so you need to find something you can measure that would have responded to the atmospheric CO." The area searched, located in the wilds of Tanzania, is known for its deposits of certain microfossils.
The team, comprised of Bridget Wade from A&M University (Texas), Paul Pearson from Cardiff University and Gavin Foster from the University of Bristol had gathered samples in Tanzania under the watch of armed guards, to protect them from predators such as lions and hyenas. Their findings, based on test results from those samples, have been published in Nature online. Called Atmospheric carbon dioxide through the oecene-oligocene climate transition, the paper outlines the findings.
The ground-breaking study is "... the first that uses some sort of proxy reconstruction of CO2 to point to the declining CO2 that most of us expected we ought to be able to find," Pearson told Reuters, adding, "CO2, being an acidic gas, causes changes in acidity in the ocean, which absorbs large amounts of the gas. We can pick that up through chemistry of microscopic plankton shells that were living in the surface ocean at the time."
Pearson continued, "Our results are really in line with the most sophisticated climate models that have been applied to this interval. Those models could be used to predict the melting of the ice. The suggested melting starts around 900 ppm (parts per million)." Pearson told Reuters that he thought "... levels of 900 ppm could be could be reached by the end of this century, unless serious emissions cuts were made."
The Antarctic ice cap has been melting for years. In 2005, scientists said they had evidence that over 13,000 square kilometers of ice had been lost to melting.
Whether or not these new findings might influence the upcoming climate change negotiations in Copenhagen this December remains to be seen.
Update, September 16, 2009:
I reached Professor Paul Pearson by email , asking him about the 900 ppm level that Reuters had cited. Pearson was kind enough to respond, and he said:
"We did not say that unless serious cuts to emissions are made, global warming will ensure the loss of the ice cap. What we said, in the Reuters interview, is that our results are in line (within very large uncertainty limits, but that bit wasn't reported) with the most sophisticated computer models of the climate transition and growth of Antarctic ice at the Eocene-Oligocene boundary. These are the models of Pollard and Deconto, Deconto and Pollard, and Deconto and others (see the references). Those models can be run backwards and they predict melting of the Antarctic ice cap begins at about 900 ppm. That is a level that could be reached by the end of the century according to the Intergovernmental Panel on Climate Change scenarios. If you want to infer from this that without emissions cuts global warming will ensure the loss of the ice cap, that is a reasonable inference, but it is your inference, and has to be made with an understanding of the limitations of the models."
Pearson went on to explain that there is a distinction between the East Antarctic ice cap, and the rest of the Antarctic. He said that "...West Antarctica and Greenland melt at much lower carbon dioxide forcings in their models. Hence the models [are] not inconsistent with the idea that the Greenland ice cap may have already started melting."
I had asked what the current CO2 level was, and Pearson said that is is "...about 386 ppm as measured at Mauna Loa, Hawaii, rising at a little under 2 ppm per year." Pearson refers readers to co2now.
Pearson said "We strongly support calls for emissions cuts and the widespread view that to avoid potentially catastrophic climate change the CO2 level in the atmosphere must be stabilized. Scientists differ in their estimation of what CO2 level we should be aiming at, as there are lots of uncertainties it is partly a political issue, but speaking for myself, I think a long-term target of 350 ppm is a reasonable goal that balances effort and risk." Pearson also refers readers to 350.org.