Regional to global impacts of boreal biomass burning emissions changes: a multi-model study

Wildfire activity in boreal regions is changing, due to climate change and other anthropogenic drivers. Given the high climate sensitivity of the Arctic and boreal regions, it is important to explore the impacts of these changes. There are also region-specific impacts of biomass burning particular to high latitude regions, such as black carbon (BC) deposition on snow. While many sources of atmospheric pollutions are being mitigated, fires are emerging as a growing contributor to poor air quality, both locally to the fire emissions source and across wider regions.

Here we investigate the climate and atmospheric impacts of several idealised biomass burning perturbations, focusing on aerosols. We present initial results from a new set of multi-model experiments (including CESM2, NorESM2 and EC-Earth), where biomass burning emissions are perturbed in several idealised experiments. The species concerned are: BC, SO4, organic carbon, SO2, DMS, and secondary organic aerosol precursors. We first perturb all boreal biomass burning emissions, and then smaller regions of interest individually (boreal North America, East Siberia and West Siberia). These experiments use 2005-2014 as a baseline period, and use the sum of this period as the perturbation, giving an approximately x10 perturbation in the regions of interest, in both fixed SST (30 years) and coupled (200 years) simulations. The strength and location of the aerosol changes studied here (when comparing aerosol optical depth) are comparable to the recent trends in aerosols between 2015-2024 and 2005-2014.

We will present the modelled atmospheric composition response both globally and in the focus regions described above, including teleconnections to other regions. This includes aerosol optical depth, aerosol absorption, and a breakdown by aerosol species. We will also highlight the climate response to the biomass burning perturbations, including effective radiative forcing (ERF) and fully-coupled climate response estimates.