A Stylized Study of the Climate Response to Longwave and Shortwave Forcing at the Altitude of Aviation-Induced Cirrus

Abstract

Several lines of evidence indicate that aviation-induced cirrus clouds contribute to global warming. These clouds produce both longwave and shortwave radiative forcing, yet their climate impacts are not well understood. To improve understanding of the climate effects of radiative forcing associated with aviation-induced cirrus clouds, we use the Community Earth System Model CESM1.2.2 to perform simulations with stylized longwave and shortwave forcing agents in different latitude bands. We find that for the same concentration, longwave absorbers in the sub-tropics have the largest magnitude of instantaneous radiative forcing but these absorbers in the polar regions show the largest impact on global temperature. In contrast, shortwave scatterers in the low latitudes have the largest magnitude of effective and instantaneous radiative forcing, but the global temperature response is not highly sensitive to the latitude of forcing. Our results suggest that contrail-induced warming could be reduced most effectively by avoiding aviation-induced cirrus clouds at night, and at high latitudes during their winters.