Enhanced simulated early 21st century Arctic sea ice loss due to CMIP6 biomass burning emissions | CU Experts

The mechanisms underlying decadal variability in Arctic sea ice remain; actively debated. Here we show that variability in boreal biomass; burning (BB) emissions strongly influences simulated Arctic sea ice on; multi-decadal timescales. In particular, we find that a strong; acceleration in sea ice decline in the early 21st century in the; Community Earth System Model version 2 (CESM2) is related to increased; variability in prescribed CMIP6 BB emissions through summertime; aerosol-cloud interactions. Furthermore, we find that more than half of; the reported improvement in sea ice sensitivity to CO2 emissions and; global warming from CMIP5 to CMIP6 can be attributed to the increased BB; variability, at least in the CESM. These results highlight a new kind of; uncertainty that needs to be considered when incorporating new; observational data into model forcing, while also raising questions; about the role of BB emissions on the observed Arctic sea ice loss.

DeRepentigny P; Jahn A; Holland M; Kay J; Fasullo J; Lamarque J-F; Tilmes S; Hannay C; Mills M; Bailey D

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