IGOS Cryosphere Theme


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Theme Report


The IGOS Cryosphere Challenge
In recent years, the cryosphere has received increasing attention from the climate science community, national and international policy makers, the media, and the general public. There are a variety of reasons for this, including:
  • The cryosphere is an inherent component of the Earth Climate System and is probably the most under-sampled element within it.
  • The cryosphere, particularly glaciers, the Greenland ice sheet, permafrost, and Arctic sea-ice, is expected to undergo dramatic changes associated with the climate change. The stability of the cryosphere is therefore a high priority issue for Earth Science with many practical implications.
  • Through several feedbacks it has a large effect on the predictability of weather and climate, and knowledge of the cryosphere is therefore vital at many levels of decision-making.
  • It plays an important role in generating and mediating the conditions for a possible abrupt climate change.
  • It is one of the factors of largest uncertainty among contributors to mean sea level rise.
  • It is an important source for fresh water resources for many countries.
  • In polar regions sea-ice critically affects the pathways and hence patterns of world sea-borne trade, and strongly influences fishing activity.
  • The cryosphere provides many of the most useful indicators of long-term climate change.
The IGOS Cryosphere Theme (CryOS) is required to create a framework for improved coordination of cryospheric observations conducted by research, long-term scientific monitoring, and operational programmes, and to generate the data and information needed for both operational services and research. In the polar regions, the cost of in situ observations is very high, and satellite monitoring is challenging. Therefore there is a particularly strong need for a close coordination of observations serving the various user communities and nations. There is also a need to strengthen national and international institutional structures responsible for cryospheric observations, and to increase resources for ensuring the transition of research-based cryosphere observing projects to sustained observations. The likelihood of achieving such goals will be significantly enhanced through the development of a comprehensive, coordinated, integrated and coherent approach of the kind represented by an IGOS Theme.

A broad set of cryospheric observations and data applications are required under the Theme. We need a comprehensive system of validated remote sensing and in situ observations of the land-based cryosphere, capable of providing a complete picture of solid precipitation, snow reserves, river and lake ice, permafrost, and frozen soil characteristics. In addition to its high value for operational use (e.g., water supply management, flood forecasting, drought prediction, crop forecasts, construction stability assessment, etc.), this system will bridge meteorological and hydrological applications related to the cryosphere, and ensure the incorporation of appropriate variables in the next generation of climate and hydrological models.

We also need a significantly enhanced alpine cryosphere monitoring system to cover ice sheets, ice caps, and glaciers, including measurements of spatial extent, surface elevation, ice thickness, surface flow rate, calving rate for tidewater glaciers, equilibrium line altitude, mass balance, albedo, aerodynamic roughness, and frozen ground. The basic challenge here is to transform research-based systems like glacier monitoring into a sustained, truly global system, producing data with the accuracy required for projection of sea level rise, water management, and disaster mitigation. A combination of data sources will be required, and existing, planned and future satellite missions must be complemented by a global land-based support system.

For the ocean, the Theme will address a system of comprehensive observations of sea ice characteristics, the efficient exchange of these data, their use in operational services, and subsequent processing for research applications and climate studies. Variables of interest include ice edge position, concentration, thickness, snow depth on ice, freeboard height, floe size distribution, ridging density and ridge heights, surface albedo, melt ponds, and ice age. The system should incorporate modern advances in satellite systems and air reconnaissance, as well as surface-based and subsurface segments such as ice profiling sonars, sea-ice buoys, ship-borne, and coastal observations. Observations from ice-tethered platforms and the use of Argo-type floats under the ice may turn operational oceanography into a truly global venture. Extension of the oceanographic data assimilation efforts into ice-covered regions will be needed.

Many studies, such as freshwater flux to the oceans and the prediction of future carbon fluxes, require information from all of these areas. Methods of observation may be similar for the land- and ocean-based cryosphere, in some cases using the same satellite sensors or in situ platforms. Both will need a unified system for data management, archival and distribution. An IGOS theme for the entire cryosphere will provide economy of scale and ensure that the cryosphere is adequately addressed by the observing systems that support climate, weather and environmental research and operations. The main objective of the Cryosphere Theme is therefore to increase the coordination of existing and future activities that will facilitate the collection of validated datasets for process studies, model applications, and climate projections. The Theme does not propose to establish a new observing system for the cryosphere. Instead, its challenge is to find a way to develop and coordinate cryospheric observations on a global scale.