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though cold and often remote the icy

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reaches of the Arctic Antarctic and

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other frozen places affect the lives of

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we start our tour in Antarctica where

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they meet the sea mountains of ice crack

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and crumble the resulting icebergs can

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ice shelves surround half the continent

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they slow the relentless march of ice

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streams and glaciers like dams hold back

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rivers but the region is changing as

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temperatures increase we see a growing

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number of melt ponds as this heavy

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meltwater forces its way into cracks ice

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shelves weaken and can ultimately

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collapse after twelve thousand years the

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Larsen B Ice Shelf collapsed in just

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offshore sea ice forms when the surface

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of the ocean freezes pushing salt out of

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the ice the cold salty surface water

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starts to sink pumping deeper water out

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of the way powering global ocean

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circulation these currents influence

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climate worldwide most ice exists in the

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cold polar regions but we see glaciers

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like these in the Andes all over the

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world most are shrinking here in North

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America millions of people experience

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the cryosphere every year eastward

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moving storms deposits snow like thick

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paint brushes Mountain snow packs store

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water snowmelt provides three-quarters

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of the water resources used in the

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substantial winter snows produced a

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green Colorado in 2003 but drier

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conditions the previous year limited

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vegetation growth and increase the risk

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in the Rocky Mountains there are patches

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of frozen ground called permafrost that

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never thaw these regions are unusual in

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the mid-latitudes but farther north

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permafrost is more widespread and

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continuous covering nearly a fifth of

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the land surface in the northern

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hemisphere sea ice varies from season to

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season and from year to year data show

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that Arctic sea ice has shrunk

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dramatically in the last few decades the

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effects could be profound as polar ice

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decreases more open water could promote

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greater heating more heating could lead

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to faster melting reinforcing the cycle

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if this trend continues the Arctic Ocean

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could be ice-free in the summer by the

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end of the century these changes in ice

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cover are not limited to oceans

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Greenland's ice sheet contains nearly

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10% of the Earth's glacial ice glaciers

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in western Greenland produce most of the

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icebergs in the North Atlantic after

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decades of stability

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Greenland's Jakob saw an ice stream one

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of the fastest flowing glaciers in the

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world has changed dramatically

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the ice has thinned and the front

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retreated significantly between 1997 and

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2003 the glaciers flow rate nearly

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these are just some of the cryosphere ik

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processes that nasa satellites observe

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from space continued observation

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provides a critical global perspective

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as our home planet continues to change