Greenland Fires Ignite Climate Change Fears
Greenland Fires Ignite Climate Change Fears
11 August 2017
published by https://eos.org
Greenland / Denmark – In a real clash of fire and ice, a massive wildfire in southern Greenland has captured the worlds attention.
At the end of July, a couple of NASA satellites detected hot spots in Greenland that indicated fire, said Mark Ruminski, a team leader for a hazard mapping system of the National Oceanic and Atmospheric Administration. But fires are unexpected in Greenland, so he and his team thought it might be an error in the data.
Then a civilian pilot snapped pictures of a wildfire near Sisimiut, the second-largest city in Greenland. When clouds cleared a few days later, NASAs Landsat 8 satellite and the European Space Agencys Sentinel-2 satellites captured photos of the largest of the fires from high above.
Although ice covers nearly all of Greenland, fires do occasionally break out on the ice sheets margins. Hearing of the new sightings, Stef Lhermitte, a geoscientist who specializes in remote sensing at Delft University of Technology in the Netherlands, reviewed the past 17 years of data from NASAs Moderate Resolution Imaging Spectroradiometer (MODIS) satellite and threw together a quick analysis on Twitter to help give context to the situation.
Mark Parrington, an atmospheric chemist who works with the European Unions Copernicus Earth observation program, also tweeted an analysis of carbon dioxide emissions that indicates spikes of fire activity in 2015, 2016, and 2017.
No Fuel, No Fire
Although the current fires cause remains a mystery, peat from thawed permafrost could be its fuel, said Jessica McCarty, a geographer at Miami University in Oxford, Ohio, who specializes in geospatial analysis of wildfires.
Permafrost, or permanently frozen soil, lies under multiple meters of an active soil layer that thaws seasonally. But in certain areas, when ice within the thawing permafrost layer melts, it can expose peat, a material that forms after decomposing plants get smashed down for centuries.
The peat is made up of organic matter, most notably carbon, McCarty said. Given how readily it burns, she added, its almost like one giant charcoal briquette.
McCarty suspects the fires fuel is peat for several reasons. First, the fire isnt moving, like it would in a forest (not that there are any trees to speak of in this region of Greenland, she noted). In addition, the fires smoke is white, indicating damp fuel, like freshly thawed permafrost.
If the fire is being fueled by thawed permafrost, there may be underlying climate change implications, McCarty continued. The climate change [connection] is that there would be no fires here in Greenland if there were no fuel, and the only way that theres fuel is if the permafrost is [thawed].
Personally, this is very disturbing to me, McCarty said, because the fire indicates significant permafrost degradation sooner than [scientists] thought it would happen. Researchers project significant permafrost loss in Greenland by the end of the century. Not 2017, she said.
Permafrost Thaw
In 2011, scientists at the University of Alaska Fairbanks modeled the fate of Greenlands permafrost under a changing climate. Researchers study permafrost because of its potential to thaw and subsequently release carbonin the form of methane and carbon dioxideinto the atmosphere. Permafrost makes up about 80% of Greenlands land thats not perpetually buried under ice.
The researchers wanted to know how much climate change would contribute to permafrost degradation, which is the decrease in the thickness of the permanently frozen soil. Their models revealed that by the end of the century, parts of Greenland could warm 1.99°C and that the active top layer of soil could extend downward an additional 44 centimeters, meaning that there would be less ice locking in carbon.
Most of the terrestrial [ice-free] portion of Greenland is at risk of permafrost degradation, wrote Vladimir Romanovsky, a permafrost researcher at the University of Alaska Fairbanks and a coauthor on the research. Especially in southern Greenland, where the fire currently burns, permafrost degradation has already begun, Romanovsky told Eos.
Natural Versus Unnatural
Southern Greenland is already warmer than the northern region naturally, Romanovsky said, so its permafrost is more vulnerable to begin with. Because the Little Ice Age ended in the past 150200 years, some warming, and thus degradation, is natural.
Other factors contributing to permafrost degradation include glacial meltwater and human activities like constructing roads and buildings. Rising temperatures from the past 2030 years of anthropogenic climate change have probably contributed as well. And when the ice in the ancient soils melts, it can expose peat to drier conditionsa perfect recipe for fire, Romanovsky said.
Then, in a feedback loop, fire itself will add to the problem and accelerate [thawing] of permafrost, he continued, which will cause more ice in the permafrost to melt and drain away and lead to further drying.
Fire Meets Ice
The fire poses another threat, McCarty said. It could release black carbon, which might fall onto the nearby ice sheet and accelerate its melting. Burning of biomass like peat, among other things, releases black carbon, which is much darker than ice. Black carbon deposited onto ice sheets lowers the ices ability to reflect sunlight and boosts its heat absorption, McCarty said, potentially speeding up melting.
As of Tuesday, the wind was blowing smoke from the fire over the ice sheet, McCarty said. She has already started analyzing how much black carbon it might deposit.
Unfortunately, theres no telling when the fire may end, McCarty said. The longer it burns, the more it exacerbates the black carbon problem. With little to no rain in the forecast, Greenlands options are limited, she continued. Officials could either attempt to transfer water into extremely remote areas to quench the flames or wait until the years first snow, which will most likely fall next month.
