2014-05-19. The Big Melt Accelerates.

posted May 22, 2014, 9:11 AM by Alan Gould
For GSS Climate Change chapter 8.  Excerpt: Centuries from now, a large swath of the West Antarctic ice sheet is likely to be gone, its hundreds of trillions of tons of ice melted, causing a four-foot rise in already swollen seas. Scientists reported last week that the scenario may be inevitable, with new research concluding that some giant glaciers had passed the point of no return, possibly setting off a chain reaction that could doom the rest of the ice sheet. For many, the research signaled that changes in the earth’s climate have already reached a tipping point, even if global warming halted immediately. ...A full melt would cause sea level to rise 215 feet. During recent ice ages, glaciers expanded from the poles and covered nearly a third of the continents. And in the distant past there were episodes known as Snowball Earth, when the entire planet froze over. At the other extreme, a warm period near the end of the age of dinosaurs may have left the earth ice-free. Today the amount of ice is modest — 10 percent of land areas, nearly all of that in Greenland and Antarctica. ...In an analysis last year of the satellite and ground measurements, a team of scientists led by Alex S. Gardner, an earth scientist at Clark University in Worcester, Mass., who is moving to NASA’s Jet Propulsion Laboratory, concluded that, on average, glaciers in all regions were withering away, dumping 260 billion metric tons of water into the ocean every year. ...Greenland, with 10 percent of the world’s ice, has enough to raise sea level by 23 feet. “I still think Greenland is the most important thing to watch for this century,” Dr. Scambos said. ...Researchers from Dartmouth found that another side effect from global warming, forest fires, made the melting even worse. Soot from fires elsewhere in the world landed on Greenland snow, making it darker, causing it to absorb more heat.... http://www.nytimes.com/2014/05/20/science/the-melting-isnt-glacial.html - By Kenneth Chang, The New York Times.