Ice Adrift From Warming Scrapes Antarctic Seabed Bare

Kimberly Johnson
for National Geographic News
July 17, 2008

Rapid warming along the Antarctic Peninsula is causing more skyscraper-sized icebergs to break free, drift, and scour away practically all life along swaths of the seafloor, according to a new study.

Ocean-bottom scrubbings along the West Antarctic Peninsula will increase as temperatures rise, annihilating some animal and plant populations but helping others by clearing the habitat, the study said.

The study establishes for the first time the intimate link between increased scouring and declines in winter sea ice due to climate change, researchers said.

In the past, these icebergs were locked in place by winter sea ice for longer periods and only free to crash into the seabed in summer.

"Our results suggest that as the winter sea ice season shortens, the thousands of icebergs that float around the coastline of the Antarctic Peninsula will be free to move around and collide with the seabed creatures with ever increasing frequency," lead author Daniel Smale of the British Antarctic Survey, said in an e-mail.

A Significant Degree

Antarctica is one of the fastest warming regions in the world, the researchers said.

Sea temperatures around Antarctica tend to be stable, spanning from 28.8 degrees Fahrenheit (-1.8 degrees Celsius) to 35.6 degrees Fahrenheit (2 degrees Celsius).

The Bellingshausen Sea along the western side of the Antarctic Peninsula, however, has seen its temperatures increase by about a degree Celsius in the last 50 years, said marine biologist and study co-author David Barnes, also of the British Antarctic Survey.

"This may not sound like a lot, but it is nearly a third of the total annual variability" for that region of the sea, Barnes said.

The study will be published in tomorrow's issue of the journal Science.

Each winter, a frozen crust called fast ice forms on the sea's surface. It can stretch for thousands of square kilometers but is rarely found more than seven feet (two meters) thick.

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