Antarctica’s Ice Loss Is Speeding Up, with Sharp Acceleration in Past 5 Years

Antarctica’s Ice Loss Is Speeding Up, with Sharp Acceleration in Past 5 Years

SOURCE: Inside Climate News and Nature DATE: June 13, 2018 SNIP: The most complete assessment to date of Antarctica’s ice sheets confirms that the meltdown accelerated sharply in the past five years, and there is no sign of a slowdown. That means sea level is expected to rise at a rate that will catch some coastal communities unprepared despite persistent warnings, according to the international team of scientists publishing a series of related studies this week in the journal Nature. The scientists found that the rate of ice loss over the past five years had tripled compared to the previous two decades, suggesting an additional 6 inches of sea level rise from Antarctica alone by 2100, on top of the 2 feet already projected from all sources, including Greenland. Between 1992, when detailed satellite measurements started, and 2012, Antarctica lost about 76 billion tons of ice per year. But since 2012, that rate has tripled to about 219 billion tons of ice loss per year, the scientists found. Another study, published June 13 in the journal Science Advances, raises even more concerns about the vulnerability of Antarctic ice to global warming. Data from radar and laser readings of the ice enabled scientists with the University of Texas at Austin and the University of Waterloo to map a vast network of channels in the base of many ice sheets formed by intrusions of warm water. Some are several kilometers wide, said University of Texas at Austin researcher Jamin Greenbaum. They found the channels everywhere they looked, including beneath the ice shelf of the Totten Glacier, in East Antarctica, as well...
What Is Eating Away at the Greenland Ice Sheet?

What Is Eating Away at the Greenland Ice Sheet?

SOURCE: Inside Climate News DATE: April 19, 2018 SNIP: [T]emperatures are rising in the Arctic at about twice the global average. That causes melting around the edges of the ice sheet each year and reaches across more of the surface during summer heat waves. In areas near the edge of the ice sheet, things get even more interesting: a carpet of microbes and algae mixed with dust and soot, a short-lived climate pollutant, is darkening the ice sheet, absorbing the sun’s rays and accelerating the melting of the ice. New research shows this dark zone is growing. The new research, published in the journal Nature Communications, describes a geological feedback loop on the ice that’s expanding the dark zone: Warming melts the western edge of the ice sheet, releasing mineral dust from rock crushed by the ice sheet thousands of years ago. That dust blows to the surface of the ice, nurturing the microbes and algae living there. Those organisms produce colored pigments as sunscreen, which contribute to the darkening of the surface, reducing reflectivity and increasing melting. “Just the little bit of extra heat from a tiny soot particle can start transforming feathery and highly reflective snow crystals into darker, rounded grains that absorb more heat,” said climate researcher Jason...
Melting of Arctic mountain glaciers unprecedented in the past 400 years

Melting of Arctic mountain glaciers unprecedented in the past 400 years

SOURCE: Science Daily DATE: April 10, 2018 SNIP: New ice cores taken from the summit of Mt. Hunter in Denali National Park show summers there are least 1.2-2 degrees Celsius (2.2-3.6 degrees Fahrenheit) warmer than summers were during the 18th, 19th, and early 20th centuries. The warming at Mt. Hunter is about double the amount of warming that has occurred during the summer at areas at sea level in Alaska over the same time period, according to the new research. The warmer temperatures are melting 60 times more snow from Mt. Hunter today than the amount of snow that melted during the summer before the start of the industrial period 150 years ago, according to the study. More snow now melts on Mt. Hunter than at any time in the past 400 years, said Dominic Winski, a glaciologist at Dartmouth College in Hanover, New Hampshire and lead author of the new study published in the Journal of Geophysical Research: Atmospheres, a journal of the American Geophysical...
The world’s largest High Arctic lake responds rapidly to climate warming

The world’s largest High Arctic lake responds rapidly to climate warming

SOURCE: Nature Communications DATE: March 29, 2018 SNIP: In this study, we investigate how a warming climate has impacted the Lake Hazen watershed from its glacier headwaters, all the way through to the Arctic Char at the top of the aquatic foodweb, using a combination of historical, contemporary, modeled and paleoliminological datasets. We hypothesized that, due to its large size and thermal inertia, Lake Hazen would be more resilient to Arctic warming than smaller aquatic ecosystems, a number of which have already undergone significant regime shifts. However, we demonstrate that the Lake Hazen watershed was not resilient to even an ~1 °C relative increase in recent summer air temperatures. Accelerated melt in the cryosphere resulted in an ~10 times increase in delivery of glacial meltwaters, sediment, organic carbon and legacy contaminants to Lake Hazen and a reduction in summer lake ice cover. Changes to the physical and chemical components of the watershed caused an ecological reorganization of the algal (diatom) community assemblage and a decline in the physiological condition of Arctic...
Ice cores show Greenland’s melting is unprecedented in at least four centuries

Ice cores show Greenland’s melting is unprecedented in at least four centuries

SOURCE: The Washington Post DATE: March 28, 2018 SNIP: Scientists who crossed western Greenland with a fleet of snowmobiles, pulling up long cylinders of ice at camps a little more than a mile above sea level, have found evidence that the vast sheet of ice is melting faster than at any time in the past 450 years at least — and possibly much longer than that. That’s worrisome, because the snow that has fallen on the island over millennia — now compacted into ice — could raise sea levels by 20 feet if it completely melted. The new study is further evidence that Greenland is seeing a lot of melt in the present, but what’s novel is the ability to put that in context, said Twila Moon, a research scientist at the National Snow and Ice Data Center who studies Greenland but was not involved in the current study. “It’s just another type or form of evidence to support the fact that we’re seeing really dramatic, rapid, and probably unprecedented changes,” Moon said. Based on such research, “I am personally fully confident that we haven’t seen melt like this for 5,000 years,” Osterberg...