Antarctic glaciation: an atmospheric rather than an oceanic origin

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Two sections of the Paleoceanography review, following a publication other 2003 beginning in Nature, are collapsing the most commonly advanced theory to explain the formation of the ice sheet of Antarctica there 32 million years. For decades, climatologists have thought that the separation of Antarctic and Australian land there 35 million years had suppressed warm sea currents up, causing a cooling at the origin of the ice sheet several kilometers covering today the South pole. But the analysis of samples taken in 2000 on the coast of the island of Tasmania (which was in the past a bridge connecting the two continents) suggests another scenario.

Indeed, researchers from Purdue University (Indiana) and various US and international institutes (Sweden, Canada, Netherlands and United Kingdom) have found traces in sediments dating from the Eocene (between -54 and -35 million years ago) fossils of microorganisms associated with cold waters. A discovery inconsistent with the hypothesis of a warm current preventing glaciation until break continents. The team notes that it has passed two million years between open waters between Tasmania and Antarctica and rapid glaciation phenomenon (in thousands of years). For scientists, the most plausible explanation for the enigmatic warmth of this region during the Eocene and subsequent cooling would be a massive and sudden enough lower levels of carbon dioxide in the air. The same had already put forward this theory after analyzing fossils found at El Kef in Tunisia (work published in spring 2004). This theory, which remains to be confirmed, heightened concerns related to current global warming; it in fact implies that changes in the atmosphere can have a significant impact in a relative short geological period. 03 / 01 / 05

(New Theory of Antarctic Ice Cap)
http://www.washingtonpost.com/wp-dyn/articles/A43455-2005Jan2.html
http://web.ics.purdue.edu/~huberm/
http://news.uns.purdue.edu/html4ever/2004/041227.Huber.Antarctica.html

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