Antarctica's ice sheets are melting much faster than they did in the past decade, raising concerns that global warming may be contributing more to sea-level rise than previously thought.
The findings, from a study co-authored by Kansas University researchers, will be published in the Oct. 8 issue of the journal Science.
"It's going to affect a lot of people, because hundreds of millions of people are living within a kilometer of a coastline," said Pannirselvan Kanagaratnam , a research associate professor at KU. "If this keeps going, it can be devastating."
The KU research, using airplane-based radar developed at the university, showed 253 cubic kilometers of ice from a section of western Antarctica near the Amundsen Sea are moving from the glaciers each year, a volume equal to about 241,000 Empire State buildings. Previous estimates based on data from the 1990s were closer to 150 cubic kilometers a year, said Prasad Gogineni , the KU electrical engineering professor who led the university's participation in the project.
The research shows that sea-level rise from melting in the area studied -- which represents less than half of Antarctica -- would raise ocean levels worldwide 0.24 millimeters a year. Previous estimates were that melting on the entire continent would contribute that much to sea-level rise.
Although 0.24 millimeters is a negligible amount, experts said if the glacier thinning were to continue accelerating, the sea-level rise could become more troubling during the next century or more. If the Amundsen Sea glaciers alone were to collapse, they would raise sea levels about 4 feet, the study said.
Two other studies, published Wednesday in Geophysical Research Letters, report that elsewhere several glaciers on the Antarctic Peninsula also have been thinning and flowing more rapidly than previously thought.
"I don't think sea-level rise is an immediate concern," Gogineni said. "You're talking about the long term, 50 or 100 years. But the assumptions we've made are based on gradual increases over 100 years. What we're seeing are dramatic increases."
A team of KU researchers flew over western Antarctica in 2002, bouncing radar signals off the glaciers. The information that bounces back to the plane tells scientists about the thickness of the ice.
Satellite imagery and lasers also were used to measure the shifting and melting of the glaciers.
What isn't known is the cause of the glacial changes. Robert Thomas, a NASA glaciologist and lead author on the paper, said the cause could be global warming or the result of climate changes from hundreds of years ago.
"That's the big question our study raises: Why are the ice shelves changing so rapidly?" said Robert Thomas, a NASA glaciologist. "This is the first time in 2,000 or 3,000 years, or maybe longer, those ice shelves have broken away. They're old ice shelves, and they've survived a lot. Something pretty catastrophic has happened in the last century."
|KU scientists contributed to a new research report that shows the ice sheet in Antarctica is melting much faster than previously thought.The cause of the melting is unknown, but it may be global warming or climate changes that happened hundreds of years ago. Either way, the consequences for rising sea level may be dramatic for those living along the world's coastlines.|
Thomas said KU's radar had been key to providing what scientists knew about the world's ice sheets.
"Each year, inevitably, they improve the technology," he said. "It's a far better instrument now than it was 10 years ago. That's the great power of the group: They have enough understanding of the science to understand the scientific requirements."
Kanagaratnam, the research associate professor, said although it was too early to determine if the melting was a result of global warming, he said the study should be a wake-up call to people to do what they could to decrease global warming, such as reducing harmful auto emissions.
"I think people need to pay attention to it," he said. "Certainly there's no harm in changing our ways."