Vulnerability of carbon storage in North American boreal forests to wildfires during the 21st century

Abstract

The boreal forest contains large reserves of carbon. Across this region, wildfires influence the temporal and spatial dynamics of carbon storage. In this study, we estimate fire emissions and changes in carbon storage for boreal North America over the 21st century. We use a gridded data set developed with a multivariate adaptive regression spline approach to determine how area burned varies each year with changing climatic and fuel moisture conditions. We apply the process-based Terrestrial Ecosystem Model to evaluate the role of future fire on the carbon dynamics of boreal North America in the context of changing atmospheric carbon dioxide (CO 2 ) concentration and climate in the A2 and B2 emissions scenarios of the CGCM2 global climate model. Relative to the last decade of the 20th century, decadal total carbon emissions from fire increase by 2.5-4.4 times by 2091-2100, depending on the climate scenario and assumptions about CO 2 fertilization. Larger fire emissions occur with warmer climates or if CO 2 fertilization is assumed to occur. Despite the increases in fire emissions, our simulations indicate that boreal North America will be a carbon sink over the 21st century if CO 2 fertilization is assumed to occur in the future. In contrast, simulations excluding CO 2 fertilization over the same period indicate that the region will change to a carbon source to the atmosphere, with the source being 2.1 times greater under the warmer A2 scenario than the B2 scenario. To improve estimates of wildfire on terrestrial carbon dynamics in boreal North America, future studies should incorporate the role of dynamic vegetation to represent more accurately post-fire successional processes, incorporate fire severity parameters that change in time and space, account for human influences through increased fire suppression, and integrate the role of other disturbances and their interactions with future fire regime.

The Distribution of Climate Change Public Opinion in Canada

“…Sea ice loss, thawing permafrost, and coastal erosion are already accelerating [7][8][9], and impacts from extreme weather such as droughts, flooding, and heat waves [10][11][12], as well as ecological disturbances such as wildfires and pine beetle outbreaks are projected to increase [13,14]. All of these factors make climate action in Canada both vital and difficult.…”

Resistance of the boreal forest to high burn rates

“…Models suggest this biome will experience rapid temperature increases during the 21st century, with a potential 30-500% increase in burn rates (6)(7)(8)(9). Both fire size and the frequency of large fire years are expected to increase (8,10,11), with a cascading effect on ecosystem dynamics (12)(13)(14)(15)(16) and carbon storage (17)(18)(19)(20)(21).…”

Burned Area Mapping in the North American Boreal Forest Using Terra-MODIS LTDR (2001–2011): A Comparison with the MCD45A1, MCD64A1 and BA GEOLAND-2 Products

“…Due to the slow vegetation recovery process, an increase in boreal forest burning can substantially modify the carbon balance [17].…”