Tuesday, January 25, 2011

Caleb Sharf always has something interesting to say

The world during the late Permian period.

He's an exobiologist at Columbia, someone who looks for life on other planets.
A key clue as to why the Siberian Traps could have profoundly affected the planet has been the suggestion that this volcanic region would have ignited massive coal deposits. As these burned they would have dumped colossal amounts of ash, carbon dioxide and other combustion byproducts like sulfuric acid, and even methane into the atmosphere. Now a new work in Nature Geoscience by Grasby et al. describes the discovery of precisely the kind of ash deposits in the rock record of far northern Canada that would have been produced by the Siberian volcanoes. Not only that, but the nature of this ash is very similar to that produced by modern industrial coal use, suggesting that toxic slurry would have been pouring into the late Permian marine environment.

What is particularly interesting to my mind, which harks back to earlier posts, is that obviously the coal deposits that the Siberian lava ignited were themselves the product of a much earlier era of rich plant life - perhaps during the Carboniferous period some 300-360 million years ago. At the risk of greatly oversimplifying things it nonetheless seems that the exuberant growth of plant life, together with circumstances that led to burial and fossilization as coal, some 50 million years before the late Permian helped set a time-bomb for future organisms. I think we (astronomers, exoplanetary scientists) tend to ignore this kind of factor when we discuss planetary habitability. Extinction events are sometimes seen as random or disconnected from the deeper planetary history. Did it really matter what happened a hundred million years earlier if an asteroid comes plunging in or a super-volcano erupts? For the late Permian it looks like it did matter.

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