Physics:Cryosphere

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The cryosphere is an umbrella term for those portions of Earth's surface where water is in solid form. This includes sea ice, ice on lakes or rivers, snow, glaciers, ice caps, ice sheets, and frozen ground (which includes permafrost). Thus, there is an overlap with the hydrosphere. The cryosphere is an integral part of the global climate system. It also has important feedbacks on the climate system. These feedbacks come from the cryosphere's influence on surface energy and moisture fluxes, clouds, the water cycle, atmospheric and oceanic circulation.

Through these feedback processes, the cryosphere plays a significant role in the global climate and in climate model response to global changes. Approximately 10% of the Earth's surface is covered by ice, but this is rapidly decreasing.[1] Current reductions in the cryosphere (caused by climate change) are measurable in ice sheet melt, glaciers decline, sea ice decline, permafrost thaw and snow cover decrease.

Definition and terminology

The cryosphere describes those portions of Earth's surface where water is in solid form. Frozen water is found on the Earth's surface primarily as snow cover, freshwater ice in lakes and rivers, sea ice, glaciers, ice sheets, and frozen ground and permafrost (permanently frozen ground).

The cryosphere is one of five components of the climate system. The others are the atmosphere, the hydrosphere, the lithosphere and the biosphere.[2]: 1451 

The term cryosphere comes from the Greek word kryos, meaning cold, frost or ice and the Greek word sphaira, meaning globe or ball.[3]

Cryospheric sciences is an umbrella term for the study of the cryosphere. 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.

The term deglaciation describes the retreat of cryospheric features.

Properties and interactions

The cryosphere (bottom left) is one of five components of the climate system. The others are the atmosphere, the hydrosphere, the lithosphere and the biosphere.[2]: 1451 

There are several fundamental physical properties of snow and ice that modulate energy exchanges between the surface and the atmosphere. The most important properties are the surface reflectance (albedo), the ability to transfer heat (thermal diffusivity), and the ability to change state (latent heat). These physical properties, together with surface roughness, emissivity, and dielectric characteristics, have important implications for observing snow and ice from space. For example, surface roughness is often the dominant factor determining the strength of radar backscatter.[4] Physical properties such as crystal structure, density, length, and liquid water content are important factors affecting the transfers of heat and water and the scattering of microwave energy.

Residence time and extent

Most of the world's ice volume is in Antarctica, principally in the East Antarctic Ice Sheet. In terms of areal extent, however, Northern Hemisphere winter snow and ice extent comprise the largest area, amounting to an average 23% of hemispheric surface area in January. The large areal extent and the important climatic roles of snow and ice is related to their unique physical properties. This also indicates that the ability to observe and model snow and ice-cover extent, thickness, and radiative and thermal properties is of particular significance for climate research.[5]

Surface reflectance

The surface reflectance of incoming solar radiation is important for the surface energy balance (SEB). It is the ratio of reflected to incident solar radiation, commonly referred to as albedo. 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. Typically, albedo values for non-melting snow-covered surfaces are high (~80–90%) except in the case of forests. 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. It was found that snow cover exhibited the greatest influence on Earth's radiative balance in the spring (April to May) period when incoming solar radiation was greatest over snow-covered areas.[6]

Thermal properties of cryospheric elements

The thermal properties of cryospheric elements also have important climatic consequences. Snow and ice have much lower thermal diffusivities than air. Thermal diffusivity is a measure of the speed at which temperature waves can penetrate a substance. Snow and ice are many orders of magnitude less efficient at diffusing heat than air. Snow cover insulates the ground surface, and sea ice insulates the underlying ocean, decoupling the surface-atmosphere interface with respect to both heat and moisture fluxes. The flux of moisture from a water surface is eliminated by even a thin skin of ice, whereas the flux of heat through thin ice continues to be substantial until it attains a thickness in excess of 30 to 40 cm. However, even a small amount of snow on top of the ice will dramatically reduce the heat flux and slow down the rate of ice growth. The insulating effect of snow also has major implications for the hydrological cycle. In non-permafrost regions, the insulating effect of snow is such that only near-surface ground freezes and deep-water drainage is uninterrupted.[7]

While snow and ice act to insulate the surface from large energy losses in winter, they also act to retard warming in the spring and summer because of the large amount of energy required to melt ice (the latent heat of fusion, 3.34 x 105 J/kg at 0 °C). However, the strong static stability of the atmosphere over areas of extensive snow or ice tends to confine the immediate cooling effect to a relatively shallow layer, so that associated atmospheric anomalies are usually short-lived and local to regional in scale.[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.[9]

Climate change feedback mechanisms

Main article: Earth:Climate change feedback

There are numerous cryosphere-climate feedbacks in the global climate system. These operate over a wide range of spatial and temporal scales from local seasonal cooling of air temperatures to hemispheric-scale variations in ice sheets over time scales of thousands of years. The feedback mechanisms involved are often complex and incompletely understood. 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.[9] [11]

Components

Glaciers and ice sheets

Main articles: Earth:Glacier and Ice sheet
Representation of glaciers on a topographic map
The Taschachferner glacier in the Ötztal Alps in Austria. The mountain to the left is the Wildspitze (3.768 m), second highest in Austria. To the right is an area with open crevasses where the glacier flows over a kind of large cliff.[12]

Ice sheets and glaciers are flowing ice masses that rest on solid land. They are controlled by snow accumulation, surface and basal melt, calving into surrounding oceans or lakes and internal dynamics. The latter results from gravity-driven creep flow ("glacial flow") within the ice body and sliding on the underlying land, which leads to thinning and horizontal spreading.[13] Any imbalance of this dynamic equilibrium between mass gain, loss and transport due to flow results in either growing or shrinking ice bodies.

Aerial view of the ice sheet on Greenland's east coast

Relationships between global climate and changes in ice extent are complex. The mass balance of land-based glaciers and ice sheets is determined by the accumulation of snow, mostly in winter, and warm-season ablation due primarily to net radiation and turbulent heat fluxes to melting ice and snow from warm-air advection[14][15] Where ice masses terminate in the ocean, iceberg calving is the major contributor to mass loss. In this situation, the ice margin may extend out into deep water as a floating ice shelf, such as that in the Ross Sea.

This section is an excerpt from glacier[ edit ]
This section is an excerpt from ice sheet[ edit ]

Sea ice

Main article: Earth:Sea ice
Broken pieces of Arctic sea ice with a snow cover
Satellite image of sea ice forming near St. Matthew Island in the Bering Sea

Sea ice covers much of the polar oceans and forms by freezing of sea water. Satellite data since the early 1970s reveal considerable seasonal, regional, and interannual variability in the sea ice covers of both hemispheres. Seasonally, sea-ice extent in the Southern Hemisphere varies by a factor of 5, from a minimum of 3–4 million km2 in February to a maximum of 17–20 million km2 in September.[16][17] The seasonal variation is much less in the Northern Hemisphere where the confined nature and high latitudes of the Arctic Ocean result in a much larger perennial ice cover, and the surrounding land limits the equatorward extent of wintertime ice. Thus, the seasonal variability in Northern Hemisphere ice extent varies by only a factor of 2, from a minimum of 7–9 million km2 in September to a maximum of 14–16 million km2 in March.[17][18]

The ice cover exhibits much greater regional-scale interannual variability than it does hemispherical. For instance, in the region of the Sea of Okhotsk and Japan, maximum ice extent decreased from 1.3 million km2 in 1983 to 0.85 million km2 in 1984, a decrease of 35%, before rebounding the following year to 1.2 million km2.[17] The regional fluctuations in both hemispheres are such that for any several-year period of the satellite record some regions exhibit decreasing ice coverage while others exhibit increasing ice cover.[19]

Frozen ground and permafrost

This section is an excerpt from permafrost[ edit ]

Snow cover

Main article: Physics:Snow
Snow-covered trees in Kuusamo, Finland
Snow drifts forming around downwind obstructions

Most of the Earth's snow-covered area is located in the Northern Hemisphere, and varies seasonally from 46.5 million km2 in January to 3.8 million km2 in August.[20]


Ice on lakes and rivers

Changes caused by climate change

This section is an excerpt from Effects of climate change#Ice and snow[ edit ]

Ice sheet melt

2023 projections of how much the Greenland ice sheet may shrink from its present extent by the year 2300 under the worst possible climate change scenario (upper half) and of how much faster its remaining ice will be flowing in that case (lower half)[21]
This section is an excerpt from Greenland ice sheet[ edit ]
This section is an excerpt from Climate change in Antarctica[ edit ]

Decline of glaciers

This section is an excerpt from Retreat of glaciers since 1850[ edit ]

Sea ice decline

This section is an excerpt from Effects of climate change#Sea ice decline[ edit ]

Permafrost thaw

This section is an excerpt from Permafrost#Impacts of climate change[ edit ]

Snow cover decrease

Shrinkage of snow cover duration in the Alps, starting ca. end of the 19th century, highlighting climate change adaptation needs[22]

Studies in 2021 found that Northern Hemisphere snow cover has been decreasing since 1978, along with snow depth.[23] Paleoclimate observations show that such changes are unprecedented over the last millennia in Western North America.[24][25][23]

North American winter snow cover increased during the 20th century,[26][27] largely in response to an increase in precipitation.[28]


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. These changes also involve potentially important decadal and longer time-scale feedbacks to the climate system through temporal and spatial changes in soil moisture and runoff to the oceans.(Walsh 1995). Freshwater fluxes from the snow cover into the marine environment may be important, as the total flux is probably of the same magnitude as desalinated ridging and rubble areas of sea ice.[29] 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.{{citation needed|date=September 2023}

See also

References

  1. ↑ "Global Ice Viewer – Climate Change: Vital Signs of the Planet". https://climate.nasa.gov/interactives/global-ice-viewer/#/. 
  2. ↑ 2.0 2.1 Planton, S. (2013). "Annex III: Glossary". in Stocker, T.F.. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.. https://www.ipcc.ch/site/assets/uploads/2018/08/WGI_AR5_glossary_EN.pdf. 
  3. ↑ σφαῖρα , Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  4. ↑ Hall, Dorothy K. (1985). Remote Sensing of Ice and Snow. Dordrecht: Springer Netherlands. ISBN 978-94-009-4842-6. 
  5. ↑ "Properties of Snow – Our Winter World" (in en-US). https://ourwinterworld.org/snow-science/properties-of-snow/. 
  6. ↑ Groisman, Pavel Ya.; Karl, Thomas R.; Knight, Richard W. (14 January 1994). "Observed Impact of Snow Cover on the Heat Balance and the Rise of Continental Spring Temperatures". Science 263 (5144): 198–200. doi:10.1126/science.263.5144.198. PMID 17839175. Bibcode: 1994Sci...263..198G. https://www.science.org/doi/10.1126/science.263.5144.198. Retrieved 25 February 2022. 
  7. ↑ Lynch-Stieglitz, M., 1994: The development and validation of a simple snow model for the GISS GCM. J. Climate, 7, 1842–1855.
  8. ↑ Cohen, J., and D. Rind, 1991: The effect of snow cover on the climate. J. Climate, 4, 689–706.
  9. ↑ 9.0 9.1 Vernekar, A. D., J. Zhou, and J. Shukla, 1995: The effect of Eurasian snow cover on the Indian monsoon. J. Climate, 8, 248–266.
  10. ↑ Curry, Judith A.; Schramm, Julie L.; Ebert, Elizabeth E. (1995). "Sea Ice-Albedo Climate Feedback Mechanism" (in en). Journal of Climate 8 (2): 240–247. doi:10.1175/1520-0442(1995)008<0240:SIACFM>2.0.CO;2. ISSN 0894-8755. Bibcode: 1995JCli....8..240C. 
  11. ↑ "Error: no |title= specified when using {{Cite web}}". https://journals.ametsoc.org/view/journals/atsc/33/12/1520-0469_1976_033_2461_aarbes_2_0_co_2.xml. 
  12. ↑ Google Maps: Distance between Wildspitze and Hinterer Brochkogel, cf. image scale at lower edge of screen
  13. ↑ Greve, R.; Blatter, H. (2009). Dynamics of Ice Sheets and Glaciers. Springer. doi:10.1007/978-3-642-03415-2. ISBN 978-3-642-03414-5. 
  14. ↑ Paterson, W. S. B., 1993: World sea level and the present mass balance of the Antarctic ice sheet. In: W.R. Peltier (ed.), Ice in the Climate System, NATO ASI Series, I12, Springer-Verlag, Berlin, 131–140.
  15. ↑ Van den Broeke, M. R., 1996: The atmospheric boundary layer over ice sheets and glaciers. Utrecht, Universitiet Utrecht, 178 pp.
  16. ↑ Zwally, H. J., J. C. Comiso, C. L. Parkinson, W. J. Campbell, F. D. Carsey, and P. Gloersen, 1983: Antarctic Sea Ice, 1973–1976: Satellite Passive-Microwave Observations. NASA SP-459, National Aeronautics and Space Administration, Washington, D.C., 206 pp.
  17. ↑ 17.0 17.1 17.2 Gloersen, P., W. J. Campbell, D. J. Cavalieri, J. C. Comiso, C. L. Parkinson, and H. J. Zwally, 1992: Arctic and Antarctic Sea Ice, 1978–1987: Satellite Passive-Microwave Observations and Analysis. NASA SP-511, National Aeronautics and Space Administration, Washington, D.C., 290 pp.
  18. ↑ Parkinson, C. L., J. C. Comiso, H. J. Zwally, D. J. Cavalieri, P. Gloersen, and W. J. Campbell, 1987: Arctic Sea Ice, 1973–1976: Satellite Passive-Microwave Observations, NASA SP-489, National Aeronautics and Space Administration, Washington, D.C., 296 pp.
  19. ↑ Parkinson, C. L., 1995: Recent sea-ice advances in Baffin Bay/Davis Strait and retreats in the Bellinshausen Sea. Annals of Glaciology, 21, 348–352.
  20. ↑ Robinson, D. A., K. F. Dewey, and R. R. Heim, 1993: Global snow cover monitoring: an update. Bull. Amer. Meteorol. Soc., 74, 1689–1696.
  21. ↑ Beckmann, Johanna; Winkelmann, Ricarda (27 July 2023). "Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet" (in en). The Cryosphere 17 (7): 3083–3099. doi:10.5194/tc-17-3083-2023. Bibcode: 2023TCry...17.3083B. 
  22. ↑ Carrer, Marco; Dibona, Raffaella; Prendin, Angela Luisa; Brunetti, Michele (February 2023). "Recent waning snowpack in the Alps is unprecedented in the last six centuries" (in en). Nature Climate Change 13 (2): 155–160. doi:10.1038/s41558-022-01575-3. ISSN 1758-6798. Bibcode: 2023NatCC..13..155C. 
  23. ↑ 23.0 23.1 Fox-Kemper, B.; Hewitt, H.T.; Xiao, C.; Aðalgeirsdóttir, G.; Drijfhout, S.S.; Edwards, T.L.; Golledge, N.R.; Hemer, M. et al. (2021). Masson-Delmotte, V.; Zhai, P.; Pirani, A. et al.. eds. "Ocean, Cryosphere and Sea Level Change". Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK and New York, NY, USA) 2021: 1283–1285. doi:10.1017/9781009157896.011. ISBN 9781009157896. https://www.vliz.be/imisdocs/publications/84/371584.pdf. 
  24. ↑ Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, Connie A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, Brian H. et al. (2011-07-15). "The Unusual Nature of Recent Snowpack Declines in the North American Cordillera" (in en). Science 333 (6040): 332–335. doi:10.1126/science.1201570. ISSN 0036-8075. PMID 21659569. Bibcode: 2011Sci...333..332P. https://www.science.org/doi/10.1126/science.1201570. 
  25. ↑ Belmecheri, Soumaya; Babst, Flurin; Wahl, Eugene R.; Stahle, David W.; Trouet, Valerie (2016). "Multi-century evaluation of Sierra Nevada snowpack" (in en). Nature Climate Change 6 (1): 2–3. doi:10.1038/nclimate2809. ISSN 1758-6798. Bibcode: 2016NatCC...6....2B. https://www.nature.com/articles/nclimate2809. 
  26. ↑ Brown, Ross D.; Goodison, Barry E.; Brown, Ross D.; Goodison, Barry E. (1996-06-01). "Interannual Variability in Reconstructed Canadian Snow Cover, 1915–1992" (in EN). Journal of Climate 9 (6): 1299–1318. doi:10.1175/1520-0442(1996)009<1299:ivircs>2.0.co;2. Bibcode: 1996JCli....9.1299B. 
  27. ↑ Hughes, M. G.; Frei, A.; Robinson, D.A. (1996). "Historical analysis of North American snow cover extent: merging satellite and station-derived snow cover observations" (in en). Proceedings of the Annual Meeting - Eastern Snow Conference. Williamsburg, Virginia: Eastern Snow Conference. pp. 21–31. ISBN 9780920081181. https://books.google.com/books?id=PassAQAAMAAJ. 
  28. ↑ Groisman, P. Ya, and D. R. Easterling, 1994: Variability and trends of total precipitation and snowfall over the United States and Canada. J. Climate, 7, 184–205.
  29. ↑ Prinsenberg, S. J. 1988: Ice-cover and ice-ridge contributions to the freshwater contents of Hudson Bay and Foxe Basin. Arctic, 41, 6–11.

Template:Permafrost



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