Penn State/UMass Modeling Finds Relatively Rapid WAIS Collapses At Or Beyond 400 PPM - AFP

[hatrack]

Researchers today worry about the collapse of West Antarctic ice shelves and loss of the West Antarctic ice sheet, but little is known about the past movements of this ice. Now climatologists from Penn State and the University of Massachusetts have modeled the past 5 million years of the West Antarctic ice sheet and found the ice expanse changes rapidly and is most influenced by ocean temperatures near the continent.

"We found that the West Antarctic ice sheet varied a lot, collapsed and regrew multiple times over that period," said David Pollard, senior scientist, Penn State's College of Earth and Mineral Sciences' Earth and Environmental Systems Institute. "The ice sheets in our model changed in ways that agree well with the data collected by the ANDRILL project." Pollard and Robert M. DeConto, professor of climatology, U. Mass, reported their findings in Nature.

EDIT

The basic driver is very likely the tilt of the Earth's axis which varies with the same period, according to Pollard. However, nearer to the present, the cycle time increased to about 100,000 years as expected, driven by Northern Hemispheric ice age cycles. During past warm periods, the major collapses in the model take a few thousand years. This is also the expected time scale of future collapse of the West Antarctic ice sheet if ocean temperatures warm sufficiently - longer than a few centuries but shorter than ten thousand years.

The researchers note that when atmospheric carbon dioxide levels in the past were about 400 parts per million, in the early part of the ANDRILL record, West Antarctic ice sheet collapses were much more frequent. "We are a little below 400 parts per million now and heading higher," says Pollard. "One of the next steps is to determine if human activity will make it warm enough to start the collapse."

EDIT

http://www.terradaily.com/reports/West_Antarctic_Ice_Co...

[Nihil]

1. K & R #5

> The researchers note that when atmospheric carbon dioxide levels in the
> past were about 400 parts per million, in the early part of the ANDRILL
> record, West Antarctic ice sheet collapses were much more frequent.
> "We are a little below 400 parts per million now and heading higher,"
> says Pollard. "One of the next steps is to determine if human activity
> will make it warm enough to start the collapse."

There's not much to say here (apart from maybe "Oops?") but kicking
for visibility.

[Canuckistanian]

2. K&R