This is Section 6.1 of the Arctic Climate Impact Assessment.
Lead Author: John E.Walsh; Contributing Authors: Oleg Anisimov, Jon Ove M. Hagen,Thor Jakobsson, Johannes Oerlemans,Terry D. Prowse,Vladimir Romanovsky, Nina Savelieva,Mark Serreze, Alex Shiklomanov, Igor Shiklomanov, Steven Solomon; Consulting Authors: Anthony Arendt, David Atkinson, Michael N. Demuth, Julian Dowdeswell, Mark Dyurgerov, Andrey Glazovsky, Roy M. Koerner, Mark Meier, Niels Reeh, Oddur Sigur0sson, Konrad Steffen, Martin Truffer

The term “cryosphere” is defined^[1] as: “That part of the earth’s crust and atmosphere subject to temperatures below 0 ºC for at least part of each year”. For purposes of monitoring, diagnosis, projection, and impact assessment, it is convenient to distinguish the following components of the cryosphere: sea ice, seasonal snow cover, glaciers and ice sheets, permafrost, and river and lake ice. Sections 6.3–6.7 address each of these variables separately. In addition, section 6.2 addresses precipitation and evapotranspiration, which together represent the net input of moisture from the atmosphere to the cryosphere. Section 6.8 addresses the surface flows that are the primary hydrological linkages between the terrestrial cryosphere and other parts of the arctic system.These surface flows will play a critical role in determining the impact of cryospheric change on the terrestrial and marine ecosystems of the Arctic, as well as on arctic and perhaps global climate. Finally, Sea-level rise and coastal stability|section 6.9 addresses sea-level variations that are likely to result from changes in the cryosphere and arctic hydrology.

The different components of the cryosphere respond to change over widely varying timescales, and some of these are not in equilibrium with today’s climate. The following sections examine recent and ongoing changes in each cryospheric component, as well as changes projected for the 21st century. Summaries of the present distributions of each variable precede the discussions of change. Each section also includes brief summaries of the impacts of the projected changes, although these summaries rely heavily on references to later chapters that cover many of the impacts in more detail. Each section concludes with a brief description of the key research needs that must be met to reduce uncertainties in the diagnoses and projections discussed. Relevant information from indigenous peoples on cryospheric and hydrological variability is given in Chapter 3.

Chapter 6: Cryosphere and Hydrology 

6.1. Introduction
6.2. Precipitation and evapotranspiration
6.3. Sea ice
6.4. Snow cover
6.5. Glaciers and ice sheets
6.6. Permafrost
6.7. River and lake ice
6.8. Freshwater discharge
6.9. Sea-level rise and coastal stability

 Reference

1. ^NRCC, 1988. Glossary of Permafrost and Related Ground-ice Terms. Permafrost Subcommittee, National Research Council of Canada, Technical Memorandum 142, 156pp.