The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels.

The volume addresses the following major topics:

- Research results in measuring and observing aspects of the Arctic climate system and its processes across a range of time and space scales

- Representation of cryospheric, atmospheric, and oceanic processes in models, including assimilation of observations into models

- Our understanding of the role of the Arctic in the global climate system, its response to large-scale climate variations, and the processes involved.

The hydrological cycle of the Arctic Ocean has intimate and complex linkages to global climate: changes in one affect the other, usually with a feedback. The combined effects of large river runoff, advection of meteoric water, low evaporation rates and distillation by freezing contribute to the formation of a strong halocline in the upper Arctic ocean, which limits thermal communication between the sea ice and the warmer waters of Atlantic origin below. Sea ice and freshened surface waters are transported from the marginal seas by winds and currents, ultimately exiting the Arctic Ocean through Fram and Davis Straits. Variations in the freshwater outflow from these regions affect the density structure of the Arctic Ocean itself and so the surface heat balance. Another feedback is the effect these variations have on the density profile of the water column in the Greenland and Labrador seas where, at present, convection takes place mixing surface waters downwards with those at greater depth. This downward convective motion produces dense deep waters that flow outwards from these two centres and affect the entire North Atlantic.

The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels. The volume addresses the following major topics: - Research results in observing aspects of the Arctic climate system and its processes across a range of time and space scales - Representation of cryospheric, atmospheric, and oceanic processes in models, including simulation of their interaction with coupled models - Our understanding of the role of the Arctic in the global climate system, its response to large-scale climate variations, and the processes involved.

The hydrological cycle of the Arctic Ocean has intimate and complex linkages to global climate: changes in one affect the other, usually with a feedback. The combined effects of large river runoff, advection of meteoric water, low evaporation rates and distillation by freezing contribute to the formation of a strong halocline in the upper Arctic ocean, which limits thermal communication between the sea ice and the warmer waters of Atlantic origin below. Sea ice and freshened surface waters are transported from the marginal seas by winds and currents, ultimately exiting the Arctic Ocean through Fram and Davis Straits. Variations in the freshwater outflow from these regions affect the density structure of the Arctic Ocean itself and so the surface heat balance. Another feedback is the effect these variations have on the density profile of the water column in the Greenland and Labrador seas where, at present, convection takes place mixing surface waters downwards with those at greater depth. This downward convective motion produces dense deep waters that flow outwards from these two centres and affect the entire North Atlantic.