Informative risk analyses of radiative forcing geoengineering require proper counterfactuals

This is the authors' abstract. We don't add key points for this paper.

The study “Radiative forcing geoengineering under high CO 2 levels leads to higher risk of Arctic wildfires and permafrost thaw than a targeted mitigation scenario” by Müller, et al. 1 examines three scenarios of radiative forcing geoengineering as simulated by the Norwegian Earth System Model. The authors compare high-latitude boreal summer maximum temperatures and winter minimum temperatures in the geoengineering scenarios – stratospheric aerosol injection, marine cloud brightening, and cirrus cloud thinning – to high-warming and moderate-warming scenarios without geoengineering. They conclude that all three geoengineering interventions, which use the high-warming scenario as the baseline, worsen the risk of wildfire and permafrost thaw relative to the moderate-warming scenario because they cool the Arctic somewhat less than the global mean in their experiments. We have significant concerns about how this paper’s results and conclusions are framed.