Monday, 15 December 2014

Melting The Cryosphere - Climate Change in the icy parts of Planet Earth

The word 'cryosphere' means the frozen parts of the Earth.

Ice, water and water vapour are the three 'states' of H2O....solid, liquid and gas.
The Earth has all three, which is unusual.

Planets are usually too hot or too cold to have them all.

Ice on Earth is melting.
The Arctic is an ocean covered by sea ice.

The Arctic sea ice melts in Summer and then refreezes in Winter.
Arctic sea ice area is largest each March, and at its lowest each September.
It is reducing over time.

This graph comes from the US National Snow and Ice Data Center.

ice extent trend graph

The Antarctic is a continent covered by ice, unlike the ocean in the Arctic.

The sea ice surrounding Antarctica melts almost to the coast each summer.

The winter sea ice has increased by around 1 % over the last few decades.

This is due to complex processes.

It is linked to melting of the land ice on Antarctica…..

Seawater does not freeze until around minus 2 degrees C because it has salt.

This effect of salt, of course, is used to help defrost roads.

The meltwater off Antarctica’s ice sheets is freshwater.

Freshwater has a low density, so it forms a layer on top of the sea.

Freshwater freezes (of course) at zero degrees C.

So the top layer freezes more easily.

Also windchill helps to freeze that top layer.

A useful comparison of Antarctic and Arctic sea ice ……

For more on other parts of the cryosphere, please click here - Greenland ..... Glaciers 

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