A new study performed has shown that ongoing global warming is making conditions that will probably cause considerable increases in Arctic wildfires within the decades to come. This possibly releases enormous stores of organic carbon from burned peatlands into the air.
With the help of satellite data, Adrià Descals and collaborators have displayed that the fires in the Siberian Arctic burned around 4.7 million hectares (Mha) in 2019 and 2020. This is estimated around 44% of the complete burned area in this region for almost the past four decades.
Arctic soils store enormous amounts of organic carbon, much of which is in the form of peatlands. Despite usually being frequently waterlogged or frozen, climate warming thaws and dries peatland soils, thereby raising the probability of huge Arctic wildfires. Burning of such carbon-rich soils liberates this carbon into the air as carbon dioxide, thereby fueling a feedback loop of continued warming, CO2 emission, and succeeding burning.
Descals et al. made use of six satellite-derived maps to assess the yearly burned area in the Siberian Arctic for 1982-2020 and integrated it with a study of 10 climatic factors linked with the likelihood of fires, such as precipitation and temperature.
They discovered that fires burned at the highest rates in 2019 and 2020 and reported for nearly 44% of the complete area burned across nearly a four-decade-long study period, liberating nearly 150 million tons of carbon into the air. Also, 2019 and 2020 were the warmest years throughout the study.
As per the authors, the outcomes indicate an exponential relationship between fire linked with the yearly burned area and increased temperature. Already, the Siberian Arctic has twofold the long-term average of burned area in just the past three years of their examination.
This could denote a deep shift in the fire regimes of the region caused by expediting climatic warming.
“Larger and more intense wildfires could substantially accelerate the release of permafrost carbon into the atmosphere, but this interaction is not considered in current forecasts of Arctic feedback to global warming,” wrote Eric Post and Michelle Mack in a related Perspective.
“Future studies that link rigorous assessment of wildfires with the dynamics of permafrost thaw in these remote regions are therefore needed to better quantify their climate impact,” they added.
For reporters showing interest in trends, another study on this problem also analyzes recent extreme Siberian wildfire seasons. In this study performed, Rebecca Scholten and collaborators utilized data from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) to assess fire activity in the Siberian Arctic between 2001 and 2021.
Scholten et al. discovered that early snowmelt integrated with an anomalous Arctic front jet over northeastern Siberia encouraged remarkably dry and warm surface conditions, which were tracked by exceptionally high fire activity and lightning.
They display that such interconnected climatic drivers have been raising over the past several decades and are probably driving extreme fire activity in the region. Such fires have the ability to expedite the degradation and thawing of carbon-rich permafrost peatlands.
Descals, A., et al. (2022) Unprecedented fire activity above the Arctic Circle linked to rising temperatures. Science. doi.org/10.1126/science.abn9768.