What is Cryosphere? How does it affect Global Climate?
Guest Writer/Author: Fazal Firdausi
Cryosphere
It is the term used collectively for the portions of Earth surface, where water is present in a frozen state. It includes:
- Snow Cover
- Glaciers
- Ice Sheets
- Ice Shelves
- Freshwater Ice
- Sea Ice
- Icebergs
- Permafrost
- Ground Ice
The word “Cryo” has come from the Greek meaning “Icy Cold”. The term Cryosphere was first introduced by Dobrowolski and Barry et.al. (2011) and elaborated by Shumskii (1964).
Cryosphere is an integral part of the global climate system. It has important linkages and feedbacks with the atmosphere and hydrosphere. For example:
It affects surface energy and discharge of moisture, as it releases large amount of freshwater, when snow ice melts. Release of freshwater due to melting and its locking due to freezing (both) are directly linked to the thermohaline circulation. Cryosphere has deep influence on atmospheric processes such as formation of clouds and precipitation. Any change in the amount of freshwater coming from Cryosphere into lands and oceans can affect surface hydrology.
How does Cryosphere Affect Global Climate?
- The cryosphere is linked to the Ice-Albedo mechanism. Since
snow cover and floating ice provide insulation to the land surface. As a result of its reflectivity, snow contributes to the maintenance of the Earth’s heat balance, which in turn serves to cool the planet. The absence of snow cover will result in higher mean-annual surface temperatures. - At the same time, the floating ice insulates the water beneath the oceans and prevents it from further freezing, helping maintain ocean temperatures.
- The absence of snow cover will also lead to severe winter cooling of the land surface and an increase in permafrost (permanently frozen subsoil) in near-pole areas.
- Cryosphere is also essential for any eustatic (uniform) changes in global sea level.
- It also affects latent heat storage (involved in phase changes) between ice and water.
- Permafrost modulates water and energy discharges and the exchange of carbon (specially methane) between land and the atmosphere.
Cryosphere and Climate Change
According to the study conducted by Anthony and Bamber of Bristol University, Cryosphere is far more sensitive to climate change than it has been estimated. They have tried to prove it through examples of melting margins of Greenland glaciers, reduction of Arctic Summer Ice, melting of Alpine-Himalayan glaciers, a decline of the west Antarctic ice sheet, etc. Sea level rise due to receding glaciers could alter ocean currents and bring irreversible changes in the regional climate. It could displace millions of people from their homes. Therefore, we may say that it is not the Cryosphere at risk but potentially the entire global climate regime.
Conclusion
According to a recent scientific study, we may improve human welfare and delay global warming in critical areas such as snow and ice-covered areas by eliminating pollutants like methane and black carbon. The International Cryosphere Climate Initiative (ICCI) has been started to encourage rapid and comprehensive climate action to protect the world’s cryosphere and safeguard the lives of billions of people, particularly in mountainous, low-lying, and downstream regions. Under the National Mission for Sustaining the Himalayan Ecosystem (NMSHE) Network program on Climate Change and the Himalayan Cryosphere, India has been initiated to identify the gaps and challenges ahead concerning Climate Change and the Himalayan Cryosphere.
References:
- Barry, R., Yew Gan, T. (2011) The Global Cryosphere – Past, Present and Future, Cambridge University Press, London.
- Slaymaker, O, Kelly, E.J. (2007) The Cryosphere and Global Environmental Challenge, Blackwell Publishing, Oxford
- Bamber, J. et. al. (2004) Mass Balance of the Cryosphere, Cambridge University Press, London.