Acceleration by aerosol of a radiative-thermodynamic cloud feedback influencing Arctic surface warming

Recent work suggests that short-lived pollutants with mid-latitude origins are contributing to observed warming of the Arctic surface. Candidate mechanisms include an aerosol indirect effect'' associated with increases in cloud longwave emissivity: small cloud droplets associated with polluted conditions are efficient absorbers and emitters of longwave radiation. Here, we argue that the associated surface warming can be temporarily amplified: particulate pollution, by increasing cloud emissivity, additionally accelerates a preexisting positive feedback loop between cloud top radiative cooling and new droplet condensation. Citation: Garrett, T. J., M. M. Maestas, S. K. Krueger, and C. T. Schmidt ( 2009), Acceleration by aerosol of a radiative-thermodynamic cloud feedback influencing Arctic surface warming, Geophys. Res. Lett., 36, L19804, doi:10.1029/2009GL040195.