University of Washington researchers say the massive Western Antarctica ice sheet is collapsing and could eventually raise the world's oceans up to 15 feet, dramatically impacting coastal communities world-wide.
Scientists have warned of the collapse, based on theories, for years. But the study published in the May 16 issue of Science is the first to use detailed topography maps and computer models to determine that thinning and melting is underway and unstoppable.
"What we've been able to show with the model is that it really looks like the thinning we've been observing for the last several years is really indicative of the ongoing collapse of the ice sheet," said lead author Ian Joughin, a glaciologist at the UW's Applied Physics Laboratory.
NASA researchers have reached the same conclusions in a study to be published in Geophysical Research Letters. The study focused on the Thwaites glacier - what researchers call the soft underbelly of the Antarctic ice sheet.
"A large sector of the western Antarctic ice sheet has gone into a state of irreversible retreat. It has passed the point of no return," said Eric Rignot, a glaciologist at Nasa and the University of California, Irvine. "This retreat will have major consequences for sea level rise worldwide."
While researchers say the collapse of the ice sheet is inevitable, it's not imminent. "All of our simulations show it will retreat at less than a millimeter of sea level rise per year for a couple of hundred years, and then, boom, it just starts to really go," Joughin said.
The rising oceans could have a dramatic impact on both the Washington coast and Puget Sound. The Washington Department of Ecology says with over 2,300 miles of marine coastline, much of Washington's population lives, works, and thrives in coastal areas.
A study by University of Oregon researchers detailing the impacts, said the rising oceans will cause coastal community flooding, erosion and landslides. It will also flood wells and destroy wetlands and estuaries. The rising oceans are also predicted to cause widespread damage to key infrastructure such as Seattle's Alaskan Way seawall and bridges, and displacement of thousands.
Climate change is believed to be the leading cause of the thinning ice sheet, Joughin said. An increase in global emissions could lead to faster melting and collapse. But he says it is difficult to predict any specific timetables.