BOULDER, Colo., Feb. 13 (UPI) — A U.S. study suggests two of Greenland’s largest glaciers are melting at variable rates and not at an increasing trend.

The study, led by Ian Howat, a researcher with the University of Colorado’s National Snow and Ice Data Center and the University of Washington’s Applied Physics Laboratory, shows the glaciers shrank dramatically and dumped twice as much ice into the sea during a period of less than a year between 2004 and 2005.

But then, fewer than two years later, they returned to near their previous rates of discharge.

Howat says such variability during such a short time underlines the problem in assuming glacial melting and sea level rise will necessarily occur at a steady upward trajectory.

“Our main point is that the behavior of these glaciers can change a lot from year to year, so we can’t assume to know the future behavior from short records of recent changes,” he said. “Future warming may lead to rapid pulses of retreat and increased discharge rather than a long, steady drawdown.”

The research is online in the journal Science Express.

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