Scientists are keeping their eyes on more than 100 fires burning in the Arctic, saying 2019 appears to be an unprecedented year for their numbers and emissions.
It’s not unusual to see fires in Arctic regions, especially in sections with boreal forest. Their numbers and size fluctuate from year to year. But this year is notable, said Mark Parrington, a senior scientist at the European Centre for Medium-range Weather Forecasts.
“For sure, the emissions we can estimate, and the number of fires we can see, are much higher,” for June, he said when looking back at 16 years worth of data.
Parrington said this year, between 250 and 300 fire detections, or “hot spots,” have been recorded north of the Arctic Circle each day.
That’s four to five times higher than previous years. Normally, Parrington sees between 50 and 60 hot spots a day, which he estimates amounts to between 100 and 200 fires.
“Several hot spots can belong to the same fire, and individual fires can persist over several days.
The first hot spots of the season popped up in Siberia around the second week of June, right where the centre’s climate monitoring services were reporting high temperatures and low precipitation.
Recent satellite imagery shows that several large fires were burning in Siberia and northern Alaska. There were three fires burning and actively spreading in the Canadian Arctic, including in Yukon near the Alaska border, and near Inuvik, N.W.T. There was also a small fire on the Nunavut/Manitoba border and even one fire in Greenland. Most are caused by lightning.
Earth-observation satellites detect heat from wildfires. Based on their intensity, researchers can estimate the amount of carbon dioxide they emit.
“It certainly woke me up,” said Thomas Smith about seeing fires appear earlier in the wildfire season. He studies peat fires around the world as an associate professor at the London School of Economics.
Smith believes, based on satellite observations alone, that some Arctic fires are likely penetrating deep into the soil, releasing carbon that’s been trapped for hundreds of years.
That’s a problem because fires in peat moss emit about 10 times the amount of methane per kilogram of fuel compared to regular wildfires, said Smith. This June alone, for example, saw emissions rise to 10 times the average of previous years.
“In a few weeks, a fire can burn through hundreds of years’ worth of carbon sequestration,” he explained.
“These greenhouse gas emissions, which are not offset by future regrowth, will lead to warming, and warming will increase the likelihood of peat soils being drier earlier in the summer and therefore more likely to burn.”
In Canada, Arctic wildfires are becoming more frequent, but this year is turning out to be just “average,” said Dan Thompson, a forest fire research scientist with Natural Resources Canada.
While Alaska is having a “busy year,” it’s only the fifth busiest in the last two decades, said Thompson, with roughly 8,500 square kilometres burned so far.
“Fire happens all the time. It might be really busy in one part of the North, say in Siberia, but that doesn’t mean Northern Canada is busy as well,” he said.
But Thompson says big fires in the Arctic can have a global impact.
“Really big fires can put that smoke right into the stratosphere and it will travel all around the globe a few times,” he said.
That smoke can spread soot and smoke onto the Greenland ice cap, which could contribute to its rate of melt.
Is this the new normal? That’s hard to say, according to Parrington.
Between 2006 and 2015 there was “really low fire activity” in the Arctic, he said, with lots of inter-annual variability.
“We will have to wait until next year [to see] if this is part of a continuing trend or if that inter-annual variability comes back and the emissions are much lower,” he said.
“But you still need that ignition to start the fire itself. It’s really quite a complicated picture to get a clear signal or trend or to link it to climate change directly.”Autor(a): Fonte: