Cryosphere(Frozen water)

The shape of ice crystals cause ice to be less dense than liquid water This causes Ice to float with about 9% of the ice volume above water (91% below). A.k.a. the Tip of the iceberg.

Time scales relevant to the cryosphere

87% of ice is in Antarctica10% Greenland2.5% ice shelves (mostly Antarctic)

If all Ice melted sea levels would go up by about 65 meters (213 ft)

Snow cover

Essential for water resources in the western US

Roughly 75% of the Western US fresh water supply comes from snow pack.

Dendrite: Common six sided ice crystal / snow flake.

January or February have most NH snow cover.

Aside from Antarctica the SH has very little snow cover.

River and lakes Spring thaw

Most rivers are thawing earlier and freezing later.

Alpine Glaciers

Milk Lake glacier 1988

Milk Lake 2009

Glaciers around the world are in retreat

Permafrost

Methane possibly released from permafrost?

Methane possibly released from permafrost?

Methane change Since 2005

Methane change Since 2005

Methane change Since 2005

Land Ice

From GraceSee http://www.aber.ac.uk/greenland/Massbalance.html and Gravity Recovery And Climate Experiment

Right: Mass change distribution (2002-2009) across the ice sheet as determined by GRACE observations.

Land Icehttp://www.skepticalscience.com/east-antarctica-is-now-losing-ice.html

Ablation: Melt, sublimation, loss from wind, loss from flow

Equilibrium line: Accumulation = Ablation

2010 was an exceptional year for Greenland’s ice cap. Melting started early and stretched later in the year than usual. Little snow fell to replenish the losses. By the end of the season, much of southern Greenland had set a new record, with melting that lasted 50 days longer than average.

350 Gt – 1 mm sea level riseBoth Antarctica and Greenland have been losing ice over the past 8 years.

Ice flow speed increase with distance above ground

Side view

Top view:

Ice flow increases with distance from valley walls.

Basal melt can provide a lubricant to increase total ice flow.

Ice flow increases with increasing tilt of the mountain

Air bubbles trapped in ice can reveal atmospheric composition in the past (up to about 600,000 yrs).

When accumulation is greater than ablation in a certain zone the ice sheet :a)Growsb)Shrinksc)Stays the same size

Sublimation or calving

When accumulation is greater than ablation in a certain zone the ice sheet :a)Growsb)Shrinksc)Stays the same size

Sublimation or calving

Sea Ice

What happens to the water level when the ice melts?

a. Overflowsb. Goes downc. Stays the same

Sea Ice

What happens to the water level when the ice melts?

a. Overflowsb. Goes downc. Stays the same

From: http://earthobservatory.nasa.gov/Features/WorldOfChange/sea_ice.php

The yellow outline on each image shows the median sea ice extent observed by satellite sensors in September and March from 1979 through 2000.

Sept 2011

From: http://earthobservatory.nasa.gov/Features/WorldOfChange/sea_ice_south.php

http://nsidc.org/arcticseaicenews/2011/020211.html