Cryosphere
These feedbacks come from the cryosphere's influence on surface energy and moisture fluxes, clouds, the water cycle, atmospheric and oceanic circulation.
As an interdisciplinary Earth science, many disciplines contribute to it, most notably geology, hydrology, and meteorology and climatology; in this sense, it is comparable to glaciology.
These physical properties, together with surface roughness, emissivity, and dielectric characteristics, have important implications for observing snow and ice from space.
The large areal extent and the important climatic roles of snow and ice is related to their unique physical properties.
Climatologists are primarily interested in albedo integrated over the shortwave portion of the electromagnetic spectrum (~300 to 3500 nm), which coincides with the main solar energy input.
[citation needed] The higher albedos for snow and ice cause rapid shifts in surface reflectivity in autumn and spring in high latitudes, but the overall climatic significance of this increase is spatially and temporally modulated by cloud cover.
(Planetary albedo is determined principally by cloud cover, and by the small amount of total solar radiation received in high latitudes during winter months.)
Summer and autumn are times of high-average cloudiness over the Arctic Ocean so the albedo feedback associated with the large seasonal changes in sea-ice extent is greatly reduced.
In non-permafrost regions, the insulating effect of snow is such that only near-surface ground freezes and deep-water drainage is uninterrupted.
[8] In some areas of the world such as Eurasia, however, the cooling associated with a heavy snowpack and moist spring soils is known to play a role in modulating the summer monsoon circulation.
For example, Curry et al. (1995) showed that the so-called "simple" sea ice-albedo feedback involved complex interactions with lead fraction, melt ponds, ice thickness, snow cover, and sea-ice extent.
[10] The role of snow cover in modulating the monsoon is just one example of a short-term cryosphere-climate feedback involving the land surface and the atmosphere.
They are controlled by snow accumulation, surface and basal melt, calving into surrounding oceans or lakes and internal dynamics.
A glacier (US: /ˈɡleɪʃər/; UK: /ˈɡlæsiə/ or /ˈɡleɪsiə/) is a persistent body of dense ice, a form of rock,[15] that is constantly moving downhill under its own weight.
It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight.
Satellite data since the early 1970s reveal considerable seasonal, regional, and interannual variability in the sea ice covers of both hemispheres.
[33] Similarly, the area of individual permafrost zones may be limited to narrow mountain summits or extend across vast Arctic regions.
[43] Snow cover is an extremely important storage component in the water balance, especially seasonal snowpacks in mountainous areas of the world.
Though limited in extent, seasonal snowpacks in the Earth's mountain ranges account for the major source of the runoff for stream flow and groundwater recharge over wide areas of the midlatitudes.
Snowmelt runoff from the Earth's mountains fills the rivers and recharges the aquifers that over a billion people depend on for their water resources.
However, the freeze-up/break-up processes respond to large-scale and local weather factors, such that considerable interannual variability exists in the dates of appearance and disappearance of the ice.
Information on river-ice conditions is less useful as a climatic proxy because ice formation is strongly dependent on river-flow regime, which is affected by precipitation, snow melt, and watershed runoff as well as being subject to human interference that directly modifies channel flow, or that indirectly affects the runoff via land-use practices.
[50] If the Paris Agreement goal of staying below 2 °C (3.6 °F) is achieved, melting of Greenland ice alone would still add around 6 cm (2+1⁄2 in) to global sea level rise by the end of the century.
The retreat of mountain glaciers provide evidence for the rise in global temperatures since the late 19th century.
[74] Sea ice in the Arctic has declined in recent decades in area and volume due to climate change.
[87] Because of its close relationship with hemispheric air temperature, snow cover is an important indicator of climate change.
[citation needed] Global warming is expected to result in major changes to the partitioning of snow and rainfall, and to the timing of snowmelt, which will have important implications for water use and management.
[88] In addition, there is an associated pulse of precipitated pollutants which accumulate over the Arctic winter in snowfall and are released into the ocean upon ablation of the sea ice.
