Photo: Dimitar Dilkoff
A new study has discovered that the dense plumes of wildfire smoke are contributing to the warming of the Arctic region as “brown carbon” in the smoke is drifting north and attracting heat. The increasing number of wildfires, they add, can explain why heat dissipates faster in the Arctic than anywhere else, which brings up concerns about whether this effect will increase.
Smoke from wildfires in various places like Australia, Portugal, Siberia, and the US has drastically changed the color of the skies in the last decade and significantly affecting human health. The carbon released has also pushed emissions to record levels.
Scientists add that the burning is also contributing to the melting of sea ice in the Arctic.
Black carbon, the particles emitted from diesel engines, coal burning, cooking stoves, and other sources, is named the second-largest contributor to global warming, as they absorb sunlight and turn it into heat. Its effects on the environment and in the Arctic is well-documented.
But the same cannot be said for brown carbon, which mostly comes from the burning of trees and vegetation and is also created from fossil fuels to some degree. The warming effect of this less dense substance has either been ignored or underestimated.
In 2017, scientists traveled around the Arctic ocean on the Chinese icebreaker, Xue Long, to learn more about these effects. Brown carbon was previously estimated to be causing just 3% of the warming effect, but after the research in 2017, scientists found that it is causing more damage to the region than they previously thought.
“To our surprise, observational analyses and numerical simulations show that the warming effect of brown carbon aerosols over the Arctic is up to about 30% of that of black carbon,” says senior author Pingqing Fu, an atmospheric chemist at Tianjin University in China.
The study says the main source of this brown material is wildfires, and it is contributing twice as much to the warming effect in the Arctic than what came from fossil fuels.
Black carbon plays the major role in warming, but scientists say that brown carbon is also contributing to the warming of the Arctic in the last few decades.
The Arctic has been warming at three times the rate of the rest of the planet over the last five decades, and the main factor causing this is what’s termed the Arctic amplification. Ice and snow on the surface of Arctic waters usually reflect more sunlight to space, but with Arctic amplification, the darker waters absorb much more heat as the ice melts even quicker.
But the new study finds that as wildfires in mid and northern latitudes increase, the brown carbon from this source has a growing impact on the Arctic. This creates a feedback loop: as the warmer world experiences more fires, there will be less ice and more heat.
“The increase in brown carbon aerosols will lead to global or regional warming, which increases the probability and frequency of wildfires,” says Dr. Fu, explaining how the feedback loop works.
“Increased wildfire events will emit more brown carbon aerosols, further heating the earth, thus making wildfires more frequent.”
A recent UN study says that wildfires are expected to increase up to 50% by the middle of the century, so the authors of the study believe that the trend of brown carbon will increase.
The scientists also add that this shows how important managing vegetation fires is. It is not just about saving lives and limiting the damage, but it also has a role in limiting the warming of the plant.
The study has been published in One Earth.