The collapse of the West Antarctica ice sheet may be unstoppable, according to a new study.
Eric Rignot from NASA's Jet Propulsion Laboratory examined decades of climate records on the western region of the southernmost continent. He found that the western ice sheet is inherently prone to damage from climate change.
As global temperatures continue to rise, the region could experience significant melting.
The Amundsen Sea region makes up just a tiny part of the entire ice sheet of West Antarctica. But, if all the ice in the area were to melt, it could raise global sea levels by as much as four feet.
Due to extreme conditions on the frozen continent, scientists did not start careful investigations of Antarctic ice sheets until the 1950s. It was not long before scientists realized the region is unstable. This is because most of the sheet lies below sea level, by as much as a mile and a half.
Aerial views in the 1960s first suggested that ice sheets in the region often slope downward. This slope has been confirmed by mapping conducted by NASA as part of its Operation IceBridge program. This arrangement can cause water to seep between the ice and ground, accelerating the rate at which melting glaciers can escape to the open water.
In 1968, John Mercer, a geologist from Ohio State University, discovered the area has experienced dramatic physical changes from climates that had little effect on the other side of the continent, or on Greenland. Five years later, Mercer's investigation was backed up by a study from Terry Hughes of the University of Maine.
"Scientists recognized that this is the first step in a potential chain reaction. Ocean heat eats away at the ice... When ice shelves lose mass, they lose the ability to hold back inland glaciers from their march to the sea, meaning those glaciers can accelerate and thin as a result of the acceleration. In this equation, more ice flows to sea every year and sea level rises," NASA researchers wrote in a press release announcing the research.
Unlike some other ice sheets around the world, there are few "islands" in the ice to hold back the sheet. There are also few other large sheets to block its travel to the ocean. Warmer waters off the coast of the ice shelf can also help contribute to mass loss.
Researchers believe this region may be the single greatest danger to rising sea levels today. It is not known how long the region could take to melt, or what difference it will make to rising sea levels, but such an event could take a few hundred years to complete.
