Coupled Climate Responses to Recent Australian Wildfire and COVID‐19 Emissions Anomalies Estimated in CESM2
The major climate forcing events of 2019/20 include a highly anomalous Australian bushfire season and anthropogenic emissions reductions arising from COVID-19 pandemic responses. This work quantifies the climate responses to both in ensembles of CESM2 simulations driven by estimates of these climate forcings.
In demonstrating the influence of bushfire emissions on clouds and climate, this work furthers our understanding of the role of wildfire in the climate system, which is currently nascent. In doing so it also draws attention to the current simplistic representation of wildfire in climate models and associated projections as these aspects have commonly been prescribed in a highly idealized and non-interactive fashion.
The 2019/20 Australian bushfire season brightens southern hemisphere clouds and cools the southern hemisphere in CESM2, leading to a northward displacement of the ITCZ and a subsequent increase in the likelihood of La Niña in 2020/21. The climate response to COVID-19 emissions reductions in contrast is relatively weak and slowly evolving, with climate effects that were predominantly regional in scope.