This is a past event.

Tim Garrett
University of Utah

One component of rapid Arctic climate change that has received much attention over the past decade is the contribution of aerosols. Unlike in mid-latitudes, where aerosols are normally thought to have a cooling effect on climate, Arctic aerosols originating from mid-latitudes are thought to accelerate surface melting by absorbing sunlight on snow (in the case of soot) and increasing downwelling longwave thermal emission through changes in cloud microphysics (in the case of sulfates). Using a combination of ground based air measurements and ground and space based remote sensing, we've found that clouds are central to the impacts of aerosols in the Arctic. On one hand, Arctic clouds appear to be especially sensitive to perturbations in aerosol concentrations. On the other, they are a driving force in mid-latitude aerosol removal along transport pathways. In fact, observations show that both soot and sulfate are scavenged extremely efficiently by snow and rain once temperatures near the freezing threshold. This suggests that a warmer, wetter Arctic may actually end up being a cleaner Arctic.

Host Will Cantrell