Canadian wildfire soot may accelerate Greenland ice melt

What goes up must come down.

That old saying also applies to soot from Canada's massive wildfires. Plumes of thick smoke from the Fort McMurray and other Canadian wildfires billowed several thousand feet into the atmosphere in the past few weeks. Images and weather data show thick pyrocumulus and pyrocululonimbus clouds pushing over 20,000 feet into the atmosphere.

NASA satellites even captured this massive elevated smoky cyclone spinning over the Canadian Arctic in recent weeks. The smoky smudge was clearly visible from space.

Meteorologists can track elevated smoke as it is transported thousands of miles by high level winds. Soot particles have been tracked well into the Arctic, where the eventual fallout is deposited on glaciers in Greenland and Arctic Sea ice. The Dark Snow project studies the impact of albedo changes on Greenland's ice sheet.

Dark snow camp on Greenland ice sheet. NASA

Soot particles from the Canadian fires may already be changing the reflectivity of the Greenland ice sheet in 2016.

That dark snow changes the reflectivity, or albedo of snow cover. The darker surfaces allow more absorption of sunlight, and lead to more rapid snow and ice melt in summer.

This New York Times piece elaborates on why scientists are watching wildfire soot deposition in the Arctic closely.

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In addition, winds are sometimes carrying soot from the northern fires onto the immense sheet of ice covering Greenland, darkening the surface and causing it to absorb more of the sun’s heat. In 2012, such soot contributed to melting the surface of virtually the entire Greenland ice sheet, the first time that had happened since 1889.

Experts fear that more fires, and more soot, could further accelerate the melting of the ice sheet, which has the potential — should it disintegrate entirely — to raise the global sea level by more than 20 feet.

Wildfires: Climate change triple whammy

The observed increase in large wildfires is like a triple whammy for climate change.

First the burned forests lose the ability to act as a carbon sink by removing carbon for the atmosphere. Secondly the fires inject massive amounts of previously stored carbon back into the atmosphere, which acts as a feedback loop to accelerate future warming.

Grist elaborates on how that changes the atmospheric CO2 balance.

In the past week, the volume of emissions released by the Fort McMurray wildfire has mushroomed to the equivalent to 5 percent of Canada’s annual greenhouse gas emissions, reports the Edmonton Journal. And scientists have long warned that boreal forests — which run across the northern hemisphere from Canada to Alaska, Russia, and Greenland — are crucial to contain damage from climate change.

How? For one thing, the world’s forests absorb a significant amount of the carbon dioxide that humans release into the atmosphere. For another, boreal trees contain huge deposits of CO2: about 75 tons of CO2 equivalents per acre, according to Canadian Forest Service research scientists quoted in the Edmonton Journal, which is emitted as the trees burn. The problem isn’t limited to trees, but the “layers of moss, leaves, and other organic materials that insulate permafrost from surface heat,” as Yale’s environment360 project noted last year. And the really big fires melt permafrost — which contains twice as much CO2 as the trees.

And thirdly soot from the wildfires lands on ice and snow thousands of miles away in places like Greenland. That causes faster melt which warms the Arctic atmosphere. It also injects massive amounts of freshwater from the melting ice sheet into the ocean to boost sea level rises more quickly.

Now we watch this summer to see how rapidly ice in the Arctic responds to the injection of fire soot from the still ongoing Canadian wildfires.

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