Environment

The heat is on in Greenland

It's been a hot June at Kangerlussuaq, where the temperature peaked at 73°F on June 15. That's not far below the all-time hottest temperature ever recorded in Greenland of 78.6°F, set just last year on July 30 at nearby Maniitsoq Mittarfia. The unusual warmth this year melted nearly 40% of the Greenland Ice Sheet in mid-June - far above the usual 15% figure.

The warm June temperatures could be setting the stage for a big Greenland melt season this summer, and scientists with the Dark Snow Project are on the ice, 48 miles east Kangerlussuaq, conducting a two-month field experiment on the causes and implications of Greenland ice melt. The results, soon to be published, showed a pronounced spike in black carbon at the critical layer, and indicated the strong need for more research.

The "burning question": How much does wildfire and industrial soot darken the ice, increasing melt? Was the record melt and record darkness of the ice sheet in 2012 a harbinger of the future? A darker ice sheet absorbs more solar energy, in a vicious cycle that raises temperatures, melts more ice, and further darkens the ice sheet.

The amount of melting that was caused by soot from forest fires is important to know, since global warming is likely to increase the amount of forest fires in coming decades. However, the amount of forest fire soot landing on the Greenland Ice Sheet is almost completely unknown.

Greenland's ice sheet holds enough water to raise global sea levels by 7.36 meters (24.15 feet) were it all to melt, and civilization would be hard-pressed to deal with 10 - 13 feet of sea level rise from West Antarctica, let alone another 20+ feet from Greenland. "If we've committed to 3.3 meters (10.8') from West Antarctica, we haven't committed to losing Greenland, we haven't committed to losing most of East Antarctica. Those are still out there for us."

Unfortunately, the Greenland Ice Sheet is much more vulnerable to melting than previously thought, found a May 2014 study. Deeply incised submarine glacial valleys beneath the Greenland ice sheet. The researchers found that widespread ice-covered valleys extend much deeper below sea level and farther inland than previously thought, and would likely melt significantly from steadily warming waters lapping at Greenland's shores.

The ice core study found that black carbon from forest fires helped caused a RARE, near-ice-sheet-wide surface melt event that melted 97% of Greenland's surface on July 11 - 12 2012, and a similar event in 1889. Another factor contributing to a darker Greenland Ice Sheet and more melting may be additional wind-blown dust landing on the ice. "Our hypothesis is that now that seasonal snow cover in the Arctic is retreating earlier than before, and bare soil is available earlier in the Spring for dust transport."