Wildfires in US, Canadian boreal forests could release sizable amount of remaining global carbon budget

A paper by U.S. scientists published in the peer-reviewed journal Science Advances today finds that fires occurring in U.S. and Canadian boreal forests between now and 2050 could release about 3% of the remaining global carbon budget unless greater investments are made to limit fire size in these carbon-rich forests. The first-of-its-kind study was led by Dr. Carly Phillips, a fellow with the Western States Climate Team at the Union of Concerned Scientists (UCS), and co-authored with a team of researchers from the Woodwell Climate Research Center, Tufts University, Harvard University, the University of California, and Hamilton College.

The latest scientific report by the Intergovernmental Panel on Climate Change (IPCC) makes clear that countries have a quickly narrowing window to rein in heat-trapping emissions. To meet the Paris Agreement’s principal goal of limiting warming to 1.5 degrees Celsius to avoid some of the worst climate change impacts, nations need to drastically reduce heat-trapping emissions during this consequential decade and reach net-zero carbon emissions by 2050.

“Wildfires in boreal forests can be especially harmful in terms of the amount of emissions they release into the atmosphere since they store about two-thirds of the world’s forest carbon, most of which is contained in the soil and has accumulated over hundreds or even thousands of years,” said Dr. Phillips. “If not properly contained, heat-trapping emissions from wildfires in boreal forests could dramatically increase, jeopardizing nations’ ability to limit warming in line with the Paris Agreement.”

The study found that by midcentury, burned area in Alaskan and Canadian boreal forests is projected to increase as much as 169% and 150%, respectively, releasing nearly 12 gigatons of net carbon emissions—equivalent to the annual emissions of 2.6 billion cars—which represents about 3% of the remaining global carbon budget. These estimates are conservative, as the study did not assess the potential for boreal forest wildfires to accelerate permafrost thaw and other ecosystem processes that could further increase net carbon emissions.

“Governments rightly prioritize rapid suppression of wildfires that occur near heavily populated areas and crucial infrastructure, but allow other areas that hold large amounts of carbon to burn–a practice hazardous to the health and safety of communities in Alaska, Canada and beyond,” said Dr. Peter Frumhoff, a research scientist at Harvard University’s Center for the Environment and a co-author of the study. “Expanding fire management to keep wildfires near historical levels across boreal North America would provide multiple benefits and leave us far better positioned to meet the goals of the Paris Agreement.”

Despite contributing an outsized share of carbon emissions, U.S. and Canadian boreal forests are given disproportionately small amounts of funding for fire suppression efforts. Alaska, for example, accounts for roughly 20% of burned land area and half of U.S. fire emissions annually, yet only receives about 4%, on average, of federal fire management funding. The study found the average cost of avoiding the emission of 1 ton of carbon dioxide was about $12, a cost comparable to or below that of other measures to mitigate climate change. In Alaska, that would mean investing an average of $696 million per year over the next decade to keep the state’s wildfire emissions at historical levels.

“Reducing boreal forest fires to near-historical levels and keeping carbon in the ground will require additional investments,” said Dr. Brendan Rogers, an associate scientist at Woodwell Climate Research Center and co-author of the study. “These funds are comparatively low and pale in comparison to the costs countries will face to cope with the growing health consequences exacerbated by worsening air quality and the more frequent and intense climate impacts that are expected if emissions continue to rise unabated. They can also ensure wildlife, tourism, jobs, and many other facets of our society can persevere in a warming world.”

More information:
Carly A. Phillips, Escalating carbon emissions from North American boreal forest wildfires and the climate mitigation potential of fire management, Science Advances (2022). DOI: 10.1126/sciadv.abl7161. www.science.org/doi/10.1126/sciadv.abl7161