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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 2:50 PM GMT on June 25, 2014
The heat is on in Greenland, where the high temperature on Tuesday hit an unusually warm 67°F at Kangerlussuaq (Sønder Strømfjord) in southwestern 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, as documented at wunderground's extremes page. The unusual warmth this year melted nearly 40% of the Greenland Ice Sheet in mid-June, according to data from the National Snow and Ice Data Center--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.
Video 1. Glaciologist Dr. Jason Box and climate change filmmaker Peter Sinclair explain the 2013 results and 2014 mission of the Darksnow project.
The Dark Snow Project
In 2013, glaciologist Dr. Jason Box of the Geological Survey of Denmark and Greenland launched the first crowd-funded Arctic expedition: The Dark Snow Project. The field study succeeded in its scientific mission of landing a team deep within the Greenland sheet, sampling the 2012 melt layer, and returning those samples for analysis. 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.
Figure 1. Smoke from a fire in Labrador, Canada wafts over the Greenland ice sheet on June 17, 2012, as seen in this cross-section view of aerosol particles taken by NASA's CALIPSO satellite. Image credit: Dr. Jason Box, Ohio State University.
Saving Greenland's Ice Sheet is Imperative
Human-caused global warming has set in motion an unstoppable slow-motion collapse of the glaciers in West Antarctica capable of raising global sea level by 4 feet (1.2 meters) in a few hundred years, said NASA in a May 2014 press release. What's more, one of the glaciers involved, the Thwaites Glacier, acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause a total of 10 to 13 feet (3 to 4 meters) of global sea level rise over a period of centuries. This unstoppable collapse makes saving Greenland "absolutely essential", said glaciologist Richard Alley in a May 2014 interview in Mother Jones. 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," said Alley. "Those are still out there for us. And if anything, this new news just makes our decisions more important, and more powerful." Unfortunately, the Greenland Ice Sheet is much more vulnerable to melting than previously thought, found a May 2014 study by Morlighem et al., 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.
Figure 2. Monthly changes in the total mass (in Gigatonnes) of the Greenland ice sheet estimated from GRACE satellite measurements between March 2002 - July 2013. The blue and orange asterisks denote April and July values, respectively. Note that the decline in ice mass lost from Greenland is not a straight line--it is exponential, meaning that in general, more ice loss is lost each year than in the previous year. However, the mass loss during the 2013 summer melt season was probably smaller than during 2012, said the 2013 Arctic Report Card.
Support for the Dark Snow Hypothesis
Observational evidence for the Dark Snow project's hypothesis that upwind forest fires might darken the Greenland Ice Sheet and cause significant melting was provided by a May 2014 paper by Keegan et al., Climate change and forest fires synergistically drive widespread melt events of the Greenland Ice Sheet. Their 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. Since Arctic temperatures and the frequency of forest fires are both expected to rise with climate change, the results suggest that widespread melt events on the Greenland Ice Sheet may begin to occur almost annually by the end of century.
Another factor contributing to a darker Greenland Ice Sheet and more melting may be additional wind-blown dust landing on the ice, according to a June 2014 study, Contribution of light-absorbing impurities in snow to Greenland's darkening since 2009. In an interview with ClimateWire, lead author Marie Dumont of France’s meteorological agency said, "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."
Related Jeff Masters blog posts
Slow-Motion Collapse of West Antarctic Glaciers is Unstoppable, 2 New Studies Say (May 13, 2014)
Dark Snow Project: Crowd-Source Funded Science for Greenland (April 26, 2013)
Greenland experiences melting over 97% of its area in mid-July (July 25, 2012)
Record warmth at the top of the Greenland Ice Sheet (July 18, 2012)
Unprecedented May heat in Greenland; update on 2011 Greenland ice melt (May, 2012)
Greenland update for 2010: record melting and a massive calving event
The http://www.greenlandmelting.com/ website has good resources for following this year's melt progression in Greenland.
Video 2. In a follow-up video, Dark Snow Project communications director Peter Sinclair explains how the recent finding of unstoppable West Antarctic glacial melt makes the saving of Greenland's glaciers absolutely essential.
Support the Dark Snow Project
One of Dr. Box's collaborators, photographer James Balog, who created the amazing time-lapse Greenland glacier footage in the fantastic 2012 "Chasing Ice" movie, puts it like this: "Working in Greenland these past years has left me with a profound feeling of being in the middle of a decisive historic moment--the kind of moment, at least in geologic terms, that marks the grand tidal changes of history." On that note, I encourage you all to consider a tax-deductible donation to the Dark Snow Project. The project has already raised $30,000, and hopes to raise another $10,000. One of the major uses for the money will be to pay for the portable Internet satellite gear needed to do regular posting, messaging, and skyping from the ice during July and August. The June 22 update from Dr. Box, as posted in Peter Sinclair's blog: "We saw a water fountain on the horizon, spouting to 100 feet above the surface. I think it is either a lot of water trying to fall down a small moulin cavitating, or a river on the ice sheet taking a violent turn. The spout lasted at least 18 hours!"
The tropics are still quiet and expected to remain so over the next five days, so I'll have a new post on Friday.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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