Greenland is melting much faster than we thought

Greenland is melting much faster than we thought

SOURCE: Popular Science DATE: December 6, 2018 SNIP: Greenland is losing its cool. That’s not much of a surprise—its mile-thick sheet of ice was not made for this epoch of climate change. But that cool is getting shredded faster than we think. According to new findings published Wednesday in Nature, climate change has accelerated the melting of Greenland’s ice sheet to unparalleled levels, unseen in at least 350 years and likely in the past 7,800. The rate of melt and the resulting runoff falling into the ocean (and adding to a rising sea level) is speeding up over time, thanks to a motley of factors acting as a feedback loop. “By using ice cores, we can literally ‘drill back in time,’ and we are able to extend the observational period back in time ten-fold,” says Sarah Das, a glaciologist at Woods Hole Oceanographic Institution and a coauthor of the new study. In all, the team’s analysis suggests melt intensity in Greenland increased by a whopping 250 to 575 percent over just the last 20 years, relative to pre-industrial levels. In those same two decades, total ice sheet runoff has increased by 50 percent since the industrial age began, spiking up by 33 percent since the 20th century alone. Multiple factors are coalescing to create multiple feedback loops, all exacerbating the ice and snow melt. One of these is the melt-albedo feedback, in which melting creates a more granular consistency of snow that absorbs more sunlight and melts faster. Melting also exposes darker ice to sunlight, which warms up and melts faster than lighter shades of ice. And when melting...
Modest warming risks ‘irreversible’ ice sheet loss, study warns

Modest warming risks ‘irreversible’ ice sheet loss, study warns

SOURCE: NewsAsia DATE: November 13, 2018 SNIP: Even modest temperature rises agreed under an international plan to limit climate disaster could see the ice caps melt enough this century for their loss to be “irreversible”, experts warned on Monday (Nov 12). Scientists have known for decades that the ice sheets of Greenland and Antarctica are shrinking, but it had been assumed that they would survive a 1.5-2°C temperature rise relatively intact. However, according to a new analysis published in the journal Nature Climate Change, even modest global warming could cause irreversible damage to the polar ice, contributing to catastrophic sea level rises. “We say that 1.5-2°C is close to the limit for which more dramatic effects may be expected from the ice sheets,” Frank Pattyn, head of the department of geosciences, Free University of Brussels and lead study author, told AFP. His team crunched data on annual temperature rises, ice sheet coverage and known melt levels and found that both Greenland and Antarctic ice sheets would reach a “tipping point” at around 2°C. “The existence of a tipping point implies that ice-sheet changes are potentially irreversible – returning to a pre-industrial climate may not stabilise the ice sheet once the tipping point has been crossed,” said Pattyn. Many models of the 1.5-2°C scenario allow for the threshold to be breached in the short term, potentially heating the planet several degrees higher, before using carbon capture and other technologies to bring temperatures back into line by 2100. The study warned against this approach, however, saying that a feedback loop set off by higher temperatures would “lead to self-sustained melting of...
As Greenland Warms, Nature’s Seasonal Clock Is Thrown Off-Kilter

As Greenland Warms, Nature’s Seasonal Clock Is Thrown Off-Kilter

SOURCE: Yale e360 DATE: September 13, 2018 SNIP: From their perch on a rocky ridge in southwestern Greenland, graduate students Rebecca Walker and Conor Higgins peer through binoculars, looking for caribou. It’s a cool, June day and the tundra is ablaze with tiny magenta, pink, and yellow wildflowers. Crystalline lakes dot the glacially carved valleys, and from the round-topped mountains you can catch the glint of the massive Greenland Ice Sheet to the east. Below, the Watson River tumbles toward Kangerlussuaq Fjord, 12 miles to the west. It’s quiet, save for bird song, the rush of the wind, and the frequent crash of ice shearing off nearby Russell Glacier. Two decades ago, Walker and Higgins would have seen hundreds of caribou from the top of this same hill, set amid an ancestral caribou calving grounds. But these days the herds are a fraction of their former size, and Walker and Higgins spot only a handful of females and two calves a mile away. The ecologist supervising the students — Eric Post of the University of California, Davis — says the decline is very likely linked to a rapidly warming climate that is driving the schedules of caribou and the tundra plants they eat seriously out of balance. Post first came to the area 25 years ago to study calving in large herds of caribou. But around the early 2000s, he began noticing a major change. “As it got warmer and warmer and the growth season started earlier and earlier, the caribou calving season wasn’t starting earlier to the same extent,” Post says. The advancing plant growth was being triggered...
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...
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...