Study: Glacial sediment may act as buffer

STATE COLLEGE, Pa., March 1 (UPI) -- U.S. geoscientists say sediment produced by glacial movement might act as a buffer against moderate sea level increases caused by global warming.

Professor Richard Alley and colleagues at Pennsylvania State University said the finding might mean ocean temperature rise would be the key factor in glacial retreat.

"Sediment beneath ice shelves helps stabilize ice sheets against retreat in response to rise in relative sea level of at least several meters," said Alley. "Large sea level rise, such as the more than 325 feet at the end of the last ice age, may overwhelm the stabilizing feedback from sedimentation but smaller sea-level changes are unlikely to do the same."

Alley said the study's findings, along with recent evidence that ice shelves respond sensitively to ocean-temperature changes and quickly propagate the response inland, point to greater importance of other environmental variables, and especially sub-ice-shelf temperatures.

But the researchers caution sea level might be the primary control on the ice sheet if other variables, such as water temperature under ice shelves, remain stable.

The study is described online in the journal Science Express.