Pine Island Glacier melting 50% faster

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 26 June 2011

New results from an investigation into a large glacier in Antarctica and its impact on global sea level rise are published this week in the journal Nature Geoscience.

Pine Island Glacier glacier melt rate has increased significantly because more warm water is circulating beneath it.

An international team of scientists from Lamont-Doherty Earth Observatory and British Antarctic Survey has discovered that due to an increased volume of warm water reaching the cavity beneath Pine Island Glacier in West Antarctica, it’s melting 50 percent faster than it was 15 years earlier. The glacier is currently sliding into the sea at a rate of four kilometres (2.5 miles) a year, while its ice shelf (the part that floats on the ocean) is melting at about 80 cubic kilometres a year.

“More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest,” said lead author, Stan Jacobs, an oceanographer at Columbia University’s Lamont-Doherty Earth Observatory.

In 2009, Jacobs and colleagues sailed to the Amundsen Sea aboard the icebreaking ship Nathaniel B. Palmer to study the region’s thinning ice shelves — floating tongues of ice where land bound glaciers meet the sea. One goal was to study oceanic changes near Pine Island Glacier, which they had visited in an earlier trip in 1994. The researchers discovered that melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by around 0.2 degrees C, that was not enough to account for the jump. Continue reading

Antarctic thaw clues increase concerns

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 21 June 2010

A yellow submarine has helped to solve a puzzle about one of Antarctica’s fastest-melting glaciers, adding to concerns about how climate change may push up world sea levels, scientists say.

Pine Island Glacier. Photo by Tom Kellogg - 1985.

The robot submarine, deployed under the ice shelf floating on the sea at the end of the Pine Island Glacier, found that the ice was no longer resting on a subsea ridge that had slowed the glacier’s slide until the early 1970s.

Antarctica is key to predicting the rise in sea levels caused by global warming — it has enough ice to raise sea levels by 57 metres (187 ft) if it ever all melted. Even a tiny thaw at the fringes could swamp coasts from Bangladesh to Florida.

The finding from the 2009 mission “only adds to our concern that this region is indeed the ‘weak underbelly’ of the West Antarctic Ice Sheet”, co-author of the study Stan Jacobs at the Lamont-Doherty Earth Observatory said in a statement.

West Antarctica’s thaw accounts for 10% of a recently observed rise in sea levels, with melting of the Pine Island glacier quickening, especially in recent decades, according to the study led by the British Antarctic Survey (BAS) and published in the journal Nature Geoscience.

Loss of contact with the subsea ridge meant that ice was flowing faster and also thawing more as sea water flowed into an ever bigger cavity that now extended 30 km beyond the ridge.

The water was just above freezing at 1 degree Celsius (33,80F). Continue reading