Life in ice? Life in ice

Life in ice?

Life in ice? Life in ice

The cryosphere

• The portion of the Earth’s surface

covered in ice is known as the

cryosphere.

• This includes ice caps, ice sheets,

glaciers and sea ice.

• It also includes areas with

permanently frozen ground

(permafrost).

• Snow cover is part of the

cryosphere, but is seasonal not

permanent.

• Snow can cover up to 50 million

km2 of land in the northern

hemisphere winter. Seasonal snow cover in Iceland

Life in ice? Life in ice

The size of the cryosphere

• Several parts of the cryosphere vary

markedly by season.

• This includes ice on rivers, lakes and

the sea.

• Sea-ice cover in the northern

hemisphere is more variable than in

the southern hemisphere.

• Snow and ice extent varies because

of the timing of seasons in the

northern versus the southern

hemisphere

Cryosphere component

Million km2

Snow cover 47–4 (winter to summer)

Ice caps and glaciers

1

Ice sheets 16

Permafrost 25

River and lake ice 1

Sea ice 28–19 (winter to summer)

Life in ice? Life in ice

Extreme environments

• Traditionally, the cryosphere has

been grouped with other extreme

areas such as hyper-arid deserts and

areas of bare rock (see table).

• These environments were seen as

essentially unproductive in terms of

biological productivity.

• Notice that in the table ‘Extreme

desert, rock, sand, ice’ is the

third largest environment by area.

• However, it is the least productive in

terms of NPP.

Extent and productivity of global biomes

Life in ice? Life in ice

Ice life-forms•Recent research suggests there is more life in the

cryosphere than once thought.

•Most of this life is very simple, consisting of

algae.

•This includes Chlamydomonas nivalis which

looks red/pink and creates ‘watermelon snow’

and Melosira arctica which is a type of algae

that lives on the underside of floating sea ice.

•There are, rarely, more complex life-forms that

live in ice such as Alaskan ice worms

Mesenchytraeus solifugus

Life in ice? Life in ice

Food webs • The algae that live in ice form the

basis of food webs.

• The algae photosynthesise, and so

produce carbohydrate.

• Living and dead algae can be

released from ice during melting.

• This means glacial meltwater in

rivers, and ice melt from sea ice,

contains food for other organisms.

• This, simple life forms on ice can be

an important component of food

webs.