In the debate over global warming, one thing is clear: as the planet gets warmer, sea levels will rise. But how much, where and how soon? Those questions are notoriously hard to answer.
Scientists at the National Center for Atmospheric Research, in Boulder, Colo., are now adding to the complexity with a new prediction. If the melting of Greenland’s ice sheets continues to accelerate, they say, sea levels will rise even more in the northeastern United States and Maritime Canada than in other areas around the world.
The researchers, Aixue Hu and Gerald A. Meehl, based their predictions on runoff data from Greenland and an analysis of ocean circulation patterns.
They said that if Greenland melting continued to accelerate, it would alter ocean currents in a way that sends warmer water toward the northeastern and Maritime coasts. Because water expands as it warms, this influx of warmer water would raise sea levels as much as a foot or two more than in other coastal regions by the end of the century.
The researchers are reporting their findings Friday in Geophysical Research Letters, a publication of the American Geophysical Union. Their report comes two weeks after other researchers predicted that climate-related ice shifts at the South Pole would raise sea levels on the east and west coasts of North America by yet an additional 1.5 feet.
These rises in sea level, if they occur, would be on top of an overall increase of one to two feet predicted by 2100 as a result of global warming. That prediction, by the Intergovernmental Panel on Climate Change, a United Nations body, was rendered in a 2007 report that more or less ignored the question of melting glaciers and ice sheets because the process is so hard to forecast. As a result, many researchers regard the prediction as unrealistically optimistic.Continue reading the main story
The flooding potential of sea level rise depends in part on coastal topography. In places where the coast slopes gently, a rise of a few feet could send ocean waters 100 feet inland or more.
In recent years, Greenland melt rates have been increasing by 7 percent a year, the researchers said. If that continues, they said, the northeastern and Maritime Canadian coasts can expect almost two feet of additional sea level rise by 2100.
They said it was more likely that the melting would accelerate at a rate of only about 3 percent a year. In that event, they said, the region can expect an additional one foot of sea level rise.Continue reading the main story