| Domain | Terrestrial | Description | The properties of frozen ground react sensitively to climate and environmental change in high- latitude and high-altitude regions. This includes the temperature distribution in the permafrost layer and the depth of the overlying active layer where seasonal freezing and thawing occur. Changes in these quantities have important impacts on terrain stability, coastal erosion, surface and sub-surface water, the carbon cycle and vegetation development. While combined monitoring of meteorological and hydrological variables, soil and vegetation parameters, carbon dioxide and methane fluxes, and the thermal mode of the active layer and permafrost at “reference sites” is the recommended observing approach, most datasets only contain information on temperature and thickness and depth of the frozen and active layers. Standardised in situ measurements are essential, as a basis for process understanding and decision-making as well as for calibration and evaluation of climate models. [GCOS-195 6.3.8] |