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Published: Thursday 12 September, 2013

buy online isabel marant sneakers buy online isabel marant sneakers ´╗┐Antarctic ice puts climate predictions to the test



Top of pageAbstractFrozen record of the past reveals models shortcomings.



A record of greenhouse gases spanning the past 650,000 years made headlines around the globe last week. The painstaking work proves that levels of carbon dioxide and methane in the atmosphere today massively outstrip those of the preindustrial era. But it also reveals how little we understand about the way in which these gases influence global climate.



Researchers from the European Project for Ice Coring in Antarctica EPICA sampled air bubbles preserved inside a 3,000metre ice core drilled at Dome C in eastern Antarctica. The data buy online isabel marant sneakers show previous fluctuations in levels of greenhouse gases in unprecedented detail see Science 310, 1313 13 buy online isabel marant sneakers 17 2005.



Before the results were in, Eric Wolff, a physical scientist at the British Antarctic Survey in Cambridge, UK, set what came to be known as the EPICA challenge. From previously published data on the prehistoric temperature record, could anyone predict the EPICA gas record? He published the resulting efforts in September Eos 86, 341 2005.



Now that the actual figures have been published, Wolff says all of the models correctly predicted that carbon dioxide levels in the period covering the four most recent ice ages would be higher than between previous ones. The surprise was that entrants who used global models, such as Peter K of the Alfred Wegener Institute in Bremerhaven, Germany, did less well than those who considered only the Southern Ocean, such as Didier Paillard of the Laboratory of Climate and Environmental Sciences in GifsurYvette, France.



W. BERNER/UNIV. BERN



Bubble whammy: gas in ancient ice shows global models need work.



This highlights the degree to which the Southern Ocean influences global greenhousegas levels owing to its size and the fact that its cold, deep waters put large amounts of dissolved carbon dioxide out of circulation. But the less successful performance of K model, which includes factors such as the effects of vegetation, shows that comprehensive models of the carbon cycle need improvement, says Wolff.



Difficulties in predicting future climate are compounded by the fact that greenhousegas levels are set to go off the scale relative to those in the EPICA record. Carbon dioxide did not exceed 290 parts per million in the 650,000 years before the advent of fossil fuels it now stands at 375 parts per million, and many policymakers are discussing strategies to stabilize it at an ultimate level of 550. It seems like a dangerous experiment to me, says Wolff.



The results of that experiment are already starting to come in. In the past week alone, several groups have warned that the Atlantic Ocean is in trouble see Atlantic feels climate heat. Researchers hope the findings will focus world leaders, who are currently gathered in Montreal, Canada, to plan emissions policies following the en buy online isabel marant sneakers d of the first phase of the Kyoto Protocol in 2012.



Its clear that we need to stabilize greenhouse gases at a level that allows food production but avoids dangerous interference with the climate, says Thomas Stocker of the University of Bern, Switzerland, who led the latest EPICA analysis. This cannot be done by quick fixes.



Related linksRELATED STORIESIce core reveals gentle start to last ice ageRussian bid to drill Antarctic lake gets chilly responsePalaeoclimate: Frozen timeEXTERNAL LINKSCARBOOCEAN buy online isabel marant sneakers

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