Are polar ice sheets shrinking? Report offers definitive answer at last.
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Moreover, establishing a 20-year record of the ice sheets will help scientists understand the dynamics of what is going on. “We thought we understood ice sheets … but we realized we didn’t understand the physics of ice sheets very well,” said Erik Ivins of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and another team leader
Ice sheets are one of several main drivers of sea-level rise. The others – which account for the other 80 percent of sea-level rise – include the melting of glaciers and the fact that water expands as it warms, meaning seas are expanding somewhat as the atmosphere heats up. By contrast, the melting of polar sea ice has no direct effect on sea levels, since the ice is already in the water.
Researchers warn that the 11 millimeters added to sea levels by declining ice sheets since the 1990s might not sound significant, but it could be – and the storm surge from hurricane Sandy pointed to some concerns.
“We don’t fully understand or appreciate yet the physics involved in storm surges. When you have 11 millimeters of increase in sea level, it’s still a lot of mass,” says Dr. Ivins. “Small changes in sea levels in certain places mean very big changes in the kind of protection of infrastructure that you need to have in place.”