Tuesday, June 23, 2009

CO2 Linked to TJ Extinction

Scientists have unearthed striking evidence for a sudden ancient collapse in plant biodiversity. A trove of 200 million-year-old fossil leaves collected in East Greenland tells the story, carrying its message across time to us today.

Results of the research appear in this week's issue of the journal Science.

The researchers were surprised to find that a likely candidate responsible for the loss of plant life was a small rise in the greenhouse gas carbon dioxide, which caused Earth's temperature to rise.

Global warming has long been considered as the culprit for extinctions--the surprise is that much less carbon dioxide gas in the atmosphere may be needed to drive an ecosystem beyond its tipping point than previously thought.

"Earth's deep time climate history reveals startling discoveries that shake the foundations of our knowledge and understanding of climate change in modern times," says H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which partially funded the research.

Jennifer McElwain of University College Dublin, the paper's lead author, cautions that sulfur dioxide from extensive volcanic emissions may also have played a role in driving the plant extinctions.

"We have no current way of detecting changes in sulfur dioxide in the past, so it's difficult to evaluate whether sulfur dioxide, in addition to a rise in carbon dioxide, influenced this pattern of extinction," says McElwain.

The time interval under study, at the boundary of the Triassic and Jurassic periods, has long been known for its plant and animal extinctions.

[...]

The paper, "Fossil Plant Relative Abundances Indicate Sudden Loss of Late Triassic Biodiversity in East Greenland," was co-authored by McElwain, Wagner and Stephen Hesselbo of the University of Oxford in the U.K.


Paper, Please!

This is sounding more and more like the Permian Extinction Model. I'll write more as I have time. I still need to write up Dr Wignall's Guadelupean Mass Extinction paper. Oy.

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