Air-Ice Chemical Interactions (AICI)

It is now recognised that changes in one compartment of the Earth System can strongly affect the state of other compartments. Feedbacks can amplify or mitigate trends. As the Earth and its climate change, particularly in response to phenomena such as greenhouse gas increases, and stratospheric ozone depletion, it becomes increasingly important to understand the interactions between different parts of the system. This has been the basis for the new structure of IGBP, which studies the three main compartments (land, ocean, and atmosphere) and the exchanges and interactions between them. The cryosphere – ice, snow and permafrost – occurs in all three of these compartments. It forms a large proportion of the surface separating the land and ocean from the atmosphere: a seasonal maximum of 40 % of land is covered by snow or ice, while several percent of the ocean is sea-ice covered. The physical processes that involve ice are now being studied by the WCRP project CliC (Climate and Cryosphere). Until recently, it was generally assumed that the main biogeochemical role of ice was that it restricted exchanges between the more active ocean and land surfaces and the atmosphere. However, studies in recent years have revealed evidence that important chemical exchanges also occur between ice and the atmosphere, and it makes sense to study these processes and thei