WSJ, By Gautam Naik, November 29
Higher temperatures over the past two decades have caused the polar ice sheets to melt at an accelerating rate, contributing to an almost half-inch rise in global sea levels, according to the most comprehensive study done so far.
Scientists long have struggled to get a fix on whether the permanent ice sheets of Greenland and Antarctica are gaining or losing ice. Past satellite-based measurements either were limited in scope or suffered from methodological inconsistencies.
The study, published Thursday in the journal Science, estimates that the melting of the ice sheets has raised global sea levels by 11.1 millimeters (0.43 inches) since 1992. That represents one-fifth of the total sea-level increase recorded in that period.
In the 1990s, melting of the polar ice sheets was responsible for about 10% of the global sea-level rise, but now it represents about 30%, the data suggest.
“If you extrapolate these results, Greenland is going to be a serious contributor to global sea level rise” in coming years, said Peter Wadhams, a professor of ocean physics at the University of Cambridge, England, who wasn’t involved in the Science study. “Its contribution, relative to other sources, is becoming greater and greater.”
The latest effort reconciles the differences among dozens of earlier measurements and includes new data to compile an estimate that is believed to be twice as accurate as previous ones, according to researchers involved.
“It allows us to make some firm conclusions,” said Andrew Shepherd, a professor of earth observation at the University of Leeds in England and a lead author of the study. “It wasn’t clear if Antarctica was gaining or losing ice. Now we can say with confidence it is losing ice.”
Science Magazine – Commentary summary:
Experts Agree Global Warming Is Melting the World Rapidly
Science, By Richard A. Kerr, November 30
Forty-seven glaciologists have arrived at a community consensus over all the data on what the past century’s warming has done to the great ice sheets: a current annual loss of 344 billion tons of glacial ice, accounting for 20% of current sea level rise. Greenland’s share—about 263 billion tons—is roughly what most researchers expected, but Antarctica’s represents the first agreement on a rate that had ranged from a far larger loss to an actual gain. The new analysis, published on page 1183 of this week’s issue of Science, also makes it clear that losses from Greenland and West Antarctica have been accelerating, showing that some ice sheets are disconcertingly sensitive to warming.
Update – Links:
Climate Progress: Scientific American: ‘Loss of Ice, Melting Of Permafrost And Other Climate Effects Are Occurring At An Alarming Pace’
Climate Progress: Study: Sea Levels Rising 60% Faster Than Projected, Planet Keeps Warming As Expected
Climate Progress: Watch: Self-Described Climate Skeptic Says She’s Changed By ‘Chasing Ice’ Documentary
Climate Progress: Rep. Lamar Smith, Who Criticized ‘The Idea Of Human-Made Global Warming,’ Set To Chair House Science Panel
Climate Progress: November 28 News: IEA Chief Economist Sees ‘No Momentum’ For International Progress On Climate
The Guardian: Greenland and Antarctica ‘have lost 4tn tonnes of ice’ in 20 years
The scientists claim the study, published in the journal Science, ends a long-running debate over whether the vast ice sheet covering the Antarctic continent is losing or gaining mass. East Antarctica is gaining some ice, the satellite data shows, but west Antarctica and the Antarctic peninsula is losing twice as much, meaning overall the sheet is melting.
Climate Progress: Science Stunner: Greenland Ice Melt Up Nearly Five-Fold Since Mid-1990s, Antartica’s Ice Loss Up 50% In Past Decade
University of Wyoming: UW Professor’s Delayed Greenland Ice Melt Research Published in Nature
“There’s been a lot of media hype about the melting of Greenland. It’s caught the public’s imagination,” he says. “Other than the media, scientists have been predicting significant amounts of snowmelt will occur quickly in Greenland.”
However, despite the snowmelt, the meltwater runoff will not be so fast, according to Humphrey’s research.