2020 has been an exceptionally hot year for the Arctic, especially in High Arctic Russia. Beginning in January, an extended and persistent heat wave has smashed records, peaking at 38°C (100.4°F) in June. Since then, the extreme heat has continued. For example, the Russian town of Verkhoyansk in Siberia has seen over 11 days of temperatures above 30°C (80°F) in June, where the average high is just 20°C (68°F). As the scorching and unusual temperatures and lack of rain dry the surrounding landscape, unprecedented numbers of fires have followed. These blazes, more common than previous years, impact aspects of the globe far beyond the Arctic. Emissions of black carbon melt Arctic land and sea ice and snow earlier and more extensively, increasing both Arctic and Northern Hemisphere warming; and even changing mid-latitude weather patterns. Perhaps most alarmingly, fires thaw the underlying continuous permafrost — a layer of near constant frozen ground common across northern Siberia and the Arctic. The newly exposed layer of carbon-rich soils propagates the fire by providing additional belowground fuels of up to several meters in depth. In turn, Arctic fires in June released more carbon and other polluting gasses than in any previous month in the last 18 years of satellite-based monitoring. We have long known that the Arctic is especially sensitive to climate change and the 2020 fire regime is a grave example.
Fires are not uncommon in the High Arctic, though total fire numbers tend to be low compared to lower latitudes. Since High Arctic fires are closer to ice and snow, their impact on regional and global climate change is nevertheless large. To better understand the implications of an increase in High Arctic fire numbers, we focused on an Arctic subregion of the Sakha Republic, the largest federal district in Russia. At a latitude above 70°N, this subregion lies well in the Arctic circle. It also forms the southern coast of the Laptev Sea, a body of water crucial to the production of the Arctic’s sea ice. Fire activity here has a critical impact on both the local environment and the world’s climate system. Using geospatial data from two satellites (MODIS and VIIRS), a total of 8,174 fires were detected from 1 May to 13 July in the study area , with VIIRS (figure 3) detecting over 3,000 more fires than MODIS (figure 4). Moreover, three fires occurred in May 2020 early in the fire season, the closest of which was detected just 85 kilometers (52 miles) from the Laptev Sea. Cumulatively, the high density of fire activity for the past three years has originated from northern Krasnoyarsk Krai, along the Lena River, south of Yana Bay, and in the coastal plains of the East Siberian Sea (figure 5).
The same subregion of the High Arctic experienced about 7,000 fewer fires in 2018 and 2019, with 424 fires detected by MODIS and VIIRS in 2019 and 857 fires in 2018. We organized the fires into ‘fire complexes’ — contiguous areas burned by a single wildfire but detected multiple times by the satellite data — to estimate burned areas (table 1). For the spring and early summer fire season of 2020, the total burned area of the wildfire complexes in this region alone was nearly the size of the state of Vermont.
What about emissions?
Black carbon emissions, important as a short-lived climate forcer in the Arctic, are a component of particulate matter in smoke and are sometimes referred to as soot. Particulate matter from fires is also associated with respiratory morbidity. Wildfire complexes in this Arctic region of Sakha Republic burned almost 25,000 km2, emitting 17,000 metric tonnes of black carbon, emissions that were 16.2 times larger than 2019 and 8.6 times larger than 2018 (table 2). In terms of CO2, emissions from these spring and early summer 2020 wildfires for one region were equivalent to 13 times the 2019 CO2 emissions of Sweden and 2.7 times the energy-related CO2 emissions of Florida.
Carbon emissions are only part of the story, as they have far-ranging impacts regionally and globally. Smoke impacts air quality locally, causing local air quality alerts and safety orders as reported by the media in Siberia. Smoke from fires can also transport black carbon for deposition in the Arctic, increasing sea ice melt. Figure 6, from the Copernicus Atmosphere Monitoring Service and European Centre for Medium-Range Weather Forecasts shows aerosols – which include black carbon – forecasted to blow over the Laptev Sea on 12 July 2020.
A MODIS true color image from NASA WorldView observed this smoke billowing north towards the Laptev Sea, confirming the previous forecast (figure 7). Earlier in the month, smoke from fires can be seen blowing over sea ice in the Laptev Sea (figure 8).
While direct attribution may require more intense monitoring of black carbon deposition and weather patterns, it may be no coincidence that we have already seen the lowest July sea ice extent for the Laptev Sea ever as well as the lowest Arctic sea ice extent on record for July. The 2020 Arctic fire season is a clarion call to the larger climate community: the Arctic is warming, and with it, global climate feedbacks are increasing. Without far more rapid mitigation and emissions reductions, the 2020 fire season may simply be a precursor of summers to come.
By Braden D. Pohl1, Jessica L. McCarty2, and Justin J. Fain2
1 International Cryosphere Climate Initiative Summer 2020 Climate Science Intern and Undergraduate Student at St. Olaf College, Northfield, Minnesota, USA
2 Geospatial Analysis Center, Department of Geography, Miami University, Oxford, Ohio, USA