New Maps Show How Greenland’s Ice Sheet Is Melting from the Bottom Up

New Maps Show How Greenland’s Ice Sheet Is Melting from the Bottom Up

SOURCE: Scientific American DATE: November 6, 2017 SNIP: Significantly more ice in Greenland’s glaciers may be exposed to warming ocean waters than previously thought, new research suggests. Indeed, more than half the ice sheet may be subject to the melting influence of the sea. These are the latest conclusions of a detailed mapping project exploring the topography of the seafloor and bedrock around and beneath Greenland’s glaciers. Published in their final form last week in the journal Geophysical Research Letters, the maps draw on a variety of data sources, including satellite radar and aerial imagery, as well as special sonar data collected on ship expeditions to the front of the ice sheet. Included in the new paper are some of the most detailed data yet on the depths of the canyons and fjords scarring the Greenland coast, which carry water in from the sea to lap against the ice. The results suggest that the western and northern regions of Greenland are most exposed to the influence of ocean water. Out of 139 ocean-touching glaciers the team identified, they also found that 67 rest in waters 200 meters (about 650 feet) or more below sea level, where warm water is typically found—at least twice as many as previously...
New Greenland Maps Show More Glaciers at Risk

New Greenland Maps Show More Glaciers at Risk

SOURCE: NASA DATE: November 1, 2017 SNIP: New maps of Greenland’s coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as previously thought. Researchers at the University of California at Irvine (UCI), NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland’s bedrock and coastal seafloor. The new maps reveal that two to four times more oceanfront glaciers extend deeper than 600 feet (200 meters) below sea level than earlier maps showed. That’s bad news, because the top 600 feet of water around Greenland comes from the Arctic and is relatively cold. The water below it comes from farther south and is 6 to 8 degrees Fahrenheit (3 to 4 degrees Celsius) warmer than the water above. Deeper-seated glaciers are exposed to this warmer water, which melts them more rapidly. OMG Principal Investigator Josh Willis of JPL, who was not involved in producing the maps, said, “These results suggest that Greenland’s ice is more threatened by changing climate than we had...
Greenland melt speeds East Coast sea level rise

Greenland melt speeds East Coast sea level rise

SOURCE: NASA DATE: October 31, 2017 SNIP: Gravity is putting its thumb on the scale of sea level rise along the U.S. East Coast, a study tracing the effects of Greenland ice-melt shows. The recent work reveals a substantial acceleration in sea level rise, roughly from Philadelphia south, starting in the late 20th century. And it is likely a strong confirmation of sea-level “fingerprints,” one of the most counter-intuitive effects of large-scale melting: As ice vanishes, the loss of its gravitational pull lowers sea level nearby, even as sea level rises farther away. The result could be an early indication of an expected acceleration of global sea level, long predicted by computer models of Earth’s...
Scientists mapping Greenland have produced some surprising – and worrying – results

Scientists mapping Greenland have produced some surprising – and worrying – results

SOURCE: Washington Post DATE: October 4, 2017 SNIP: Two new studies of Greenland, using sophisticated technologies and large scientific teams to pull together and process the data, have now gone further in taking the full measure of the island through that ever-so-basic scientific act: mapping. The first, a comprehensive seabed mapping project, relying in part on new data from NASA’s OMG (“Oceans Melting Greenland”) mission, concludes that the Greenland ice sheet is far more exposed to the planet’s warming oceans than previously known — and has more ice to give up than, until now, has been recognized. The new research finds that “between 30 and 100% more glaciers are potentially exposed to [warm Atlantic water] than suggested by previous mapping, which represents 55% of the ice sheet’s total drainage area.” In other words, more than half of Greenland’s ice lies in or flows through areas that could be influenced by warming seas. Meanwhile, on Wednesday, a separate team of scientists used another quite different large-scale mapping exercise to document a surprising — but closely related — change in Greenland’s above-water topography. Publishing in the journal Nature, they showed that the contours of the huge island are changing because with all the ice melt rushing from glaciers to the sea, river deltas are expanding outward — a rare occurrence these days when deltas around the world are generally retreating, threatened by rising seas (think of the Mississippi River delta, for instance, and its vanishing wetlands). “Over the period of the 1980s to 2010s, rapid increase of meltwater and sediment fluxes caused dramatic advance of these deltas into the ocean,” said...
Narwhals Are Helping NASA Understand Melting Ice and Rising Seas

Narwhals Are Helping NASA Understand Melting Ice and Rising Seas

SOURCE: Bloomberg DATE: August 24, 2017 SNIP: Greenland’s ice cap holds beneath it 10 percent of the earth’s freshwater, enough to raise global sea levels by 20 feet. While there’s no doubt it is melting, scientists have little certainty about exactly what’s happening inside this 10,000-year-old ice roughly three times the size of Texas. Last winter was the warmest on record in the Arctic, and as Greenland heats up, understanding this glaciate has become essential to navigating our future. That’s why scientists need narwhals, whales with 9 foot long unicorn-like tusks, which are some of the only mammals benefiting from all that melting ice. “The narwhals like it,” said Josh Willis, the project lead for NASA’s Oceans Melting Greenland. When melting ice falls into the sea, it churns up the water, bringing such food as plankton and krill to the surface. The whales tend to feed at the bottom of melting glaciers and can dive to depths of 1,800 meters, precisely the areas that OMG needs to survey. It’s a perfect match. So far, OMG has measured Greenland’s seafloor and mapped the continental shelf, a crucial piece in the melt puzzle. “Ancient glaciers carved these troughs through the continental shelf,” Willis said. The channels allow warm water to flow between the glaciers, eating away at the ice. Unfortunately, “a lot more of these glaciers sit in deeper water than we expected,” he...