Major Antarctic glacier (Pine Island glacier) is 'past its tipping point'

[phantom power]

Climate change is warming the Amundsen Sea, which is at the southern margin of the Pacific Ocean. As rising sea levels push the warm water beneath the ice shelves, it melts them from below, pushing the grounding line higher up the continental shelf.

By raising sea levels, and therefore the grounding line, in their model, Katz's team were able to find the point of no return beyond which the glacier would be unable to recover. That's because the Antarctic sea bed has a small lip in it: it rises slowly up the continental shelf, then makes a slight dip before rising again to the shoreline. The researchers found that as long as the grounding line is on the outer rise of the sea bed, before the lip, small changes in climate lead to correspondingly small changes in the glacier's ice volume.

But as soon as the grounding line moves over the lip and starts to move down into the dip in the sea bed, the situation changes critically. "Once the grounding line passes the crest, a small change in the climate causes a rapid and irreversible loss of ice," says Katz.

According to Katz's model, the grounding line probably passed over the crest in 1996 and is now poised to enter a period of accelerated shrinking.

http://www.newscientist.com/article/dn18383-major-antarctic-glacier-is-past-its-tipping-point.html

[ensho]

1. there will be no more 'good' news about 'the melting'

going on in the world. the good news reached its tipping point too. from now on it will be bad news.

tick

[pscot]

2. A visit to Pine Island Glacier

via Google earth provides lots of context. PIG is the largest, fastest moving ice transporter on Antarctica. It's moving 75 gigatons of ice into the sea each year, and a berg that calved in 2007 was half the size of the City of London. The PIG's speed increased by 75% between 1996 and 2006. At its present rate, it will take 600 years to float the greater part of the PIG. There's more, with photos. Well worth the trip.

[highplainsdem]

3. 5th rec. This needs to be on the Greatest page.