Journal Article
Atmospheric Chemistry and Physics, vol. 18, iss. 17, pp. 13097-13113, 2018
Authors
Ben Kravitz, Philip J. Rasch, Hailong Wang, Alan Robock, Corey Gabriel, Olivier Boucher, Jason N. S. Cole, Jim Haywood, Duoying Ji, Andy Jones, Andrew Lenton, John C. Moore, Helene Muri, Ulrike Niemeier, Steven Phipps, Hauke Schmidt, Shingo Watanabe, Shuting Yang, Jin-Ho Yoon
Abstract
Abstract. Geoengineering, or climate intervention, describes methods of deliberately
altering the climate system to offset anthropogenic climate change. As an
idealized representation of near-surface solar geoengineering over the ocean,
such as marine cloud brightening, this paper discusses experiment
G1ocean-albedo of the Geoengineering Model Intercomparison Project (GeoMIP),
involving an abrupt quadrupling of the CO2 concentration and an
instantaneous increase in ocean albedo to maintain approximate net
top-of-atmosphere radiative flux balance. A total of 11 Earth system models are
relatively consistent in their temperature, radiative flux, and hydrological
cycle responses to this experiment. Due to the imposed forcing, air over the
land surface warms by a model average of 1.14 K, while air over most of the
ocean cools. Some parts of the near-surface air temperature over ocean warm
due to heat transport from land to ocean. These changes generally resolve
within a few years, indicating that changes in ocean heat content play at
most a small role in the warming over the oceans. The hydrological cycle
response is a general slowing down, with high heterogeneity in the response,
particularly in the tropics. While idealized, these results have important
implications for marine cloud brightening, or other methods of geoengineering
involving spatially heterogeneous forcing, or other general forcings with a
strong land–ocean contrast. It also reinforces previous findings that keeping
top-of-atmosphere net radiative flux constant is not sufficient for
preventing changes in global mean temperature.
