Life in ice? Life in ice Life in ice?. Life in ice The cryosphere The portion of the Earth’s...
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Transcript of Life in ice? Life in ice Life in ice?. Life in ice The cryosphere The portion of the Earth’s...
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.