Improving the Characterization of Clouds, Aerosols and the Cryosphere in Climate Models
Collaborative Institutional Lead(s):
The cryosphere, clouds and aerosols are responsible for some of the strongest feedbacks in the climate system and a large source of uncertainty in model-based assessments of climate change. In the Arctic, all of these elements combine to produce very rapid climate change. We will undertake a comprehensive and systematic study to improve the representations of these processes and to answer the questions: What are the main processes driving rapid decreases in Arctic ice cover and what are the implications of those decreases on future climate? We will bring together four DOE labs with broad expertise in these components to 1) improve model process representation of clouds, aerosols and the cryosphere, 2) embed the improved representations into the Community Climate System Model (CCSM), and 3) assess the impact of those changes for simulations of past and future climate change. For the Arctic, we will develop improved representations of sea ice strength and melt rates, Greenland ice sheet mass balance, aerosol deposition, Arctic clouds, Arctic biogeochemical feedbacks, ocean circulation and fluxes and permafrost hydrology. Improvements to global aerosol and cloud processes will also be undertaken as processes that influence non-Arctic aerosols and water vapor affect Arctic aerosols, clouds and the cryosphere. These process improvements will be tested and included in CCSM. Hindcasts of ice loss over recent decades will be used for validation and attribution. Future projections with the CCSM will be used to assess the impact of our improved representations on future climate change, particularly for a seasonally ice-free Arctic ocean.