Impact of aerosol emission controls on future Arctic sea ice cover

We examine the response of Arctic sea ice to projected aerosol and aerosol precursor emission changes under the Representative Concentration Pathway (RCP) scenarios in simulations of the Canadian Earth System Model. The overall decrease in aerosol loading causes a warming, largest over the Arctic, which leads to an annual mean reduction in sea ice extent of approximately 1 million km2 over the 21st century in all RCP scenarios. This accounts for approximately 25% of the simulated reduction in sea ice extent in RCP 4.5, and 40% of the reduction in RCP 2.5. In RCP 4.5, the Arctic ocean is projected to become ice‐free during summertime in 2045, but it does not become ice‐free until 2057 in simulations with aerosol precursor emissions held fixed at 2000 values. Thus, while reductions in aerosol emissions have significant health and environmental benefits, their substantial contribution to projected Arctic climate change should not be overlooked. Key Points Projected aerosol emission reductions drive a sea ice extent decrease of about 1 million square kilometers by 2100 Aerosol changes drive 25% of the simulated sea ice extent reduction in RCP 4.5 and 40% in RCP 2.5 Aerosol reductions result in an ice‐free Arctic about 10 years earlier than would otherwise occur