Changes in the Cryosphere and

Global Climate Change

• Carbon Dioxide has risen from ~280ppm in 1850 to 379ppm in 2005.

• Warming is now unequivocal– Increase in global average air and

ocean temperatures, rising average sea level, melting ice

• Primary forcings are anthropogenic greenhouse gases– Fossil fuel burning– Deforestation

• Similar increases in methane and nitrous oxide

Global Warming: The Basic Science

• “Canary in the coal mine”– Ice is one of the most

sensitive parts of the climate system

– Most visible symptom of climate change

– Arctic contains 1/3 of the world’s stored carbon

• Global decline in snow and ice that is accelerating.

Perito Moreno glacier Glacier National Park,

Argentina.

Why the Cryosphere?

Components

Snow Cover• Snow cover has decreased in most regions•Decreases due to temperature•Some specific increases due to precipitation•Could cause long-term freshwater shortages

• Extends and retreats every year

• Arctic sea ice extent: -2.7% per decade

• Minimum extent (in summer): -7.4% per decade

Sea Ice

• 9/3-9/9: Area of sea ice the size of Florida (69,000 mi2) melts

• Northwest Passage open for first time in human history

Recent Dramatic Events

Glaciers and Ice Caps• Studied in terms of mass balance•10% of world’s surface covered by glaciers, mostly Greenland and Antarctica•Some date back as far as the last ice age•Rapid and visible melting•Approx. 0.5 SLE 1961-2004; 0.77 SLE 1991-2004; trending higher

Visible Effects

• Defined: Glacier Ice greater than 50,000 km2. The big kahuna of glaciers!

• Greenland Ice Sheet: 7.2m SLE!• Antarctic Ice Sheet: 61m SLE!• Ice shelves extend out from connected ice sheets• Melting ice shelves can foreshadow melting ice

sheets• Ice sheets very likely already contributing to sea

level rise

Ice Sheets and Ice Shelves

Greenland and The Antarctic Ward Hunt Ice Shelf

• 2003-2005: Greenland ice sheet loses 41 mi3 at margins and gains only 14 mi3 at interior.

• Ward Hunt: – Approximately 3,000

years in age– In 2002 it began to

break upAn ice island about 1.5 kilometers long, 250 meters wide, and 30 meters thick moves into the Arctic ocean after the fracturing of the Ward Hunt Ice Shelf in August 2002. (Image courtesy of Warwick Vincent, Université Laval)

How surface melting accelerates glacier melting

• The largest part of the cryosphere in terms of surface area

• Permafrost can be ancient; some ground only freezes seasonally

• Human development on top of permafrost– Cities/towns– Oil pipelines– Roads

Frozen Ground

• Tundra/Permafrost– Contains more carbon

locked away in frozen soil than the entire atmosphere holds today

– Can release its carbon as methane, a more potent greenhouse gas

Frozen Ground

• Many polar species are particularly vulnerable to climate change because they are specifically adapted to that environment.– Food supply– Invasive new species filling niches– Fresh water supply

• Melting ice also opens up new areas to explore for human development/extraction/hunting, further threatening polar life.

Impacts on Biodiversity

Case Study: Caribou

Impacts

Increases in temperature encourage mosquito harassment

Paradoxically, warming is predicted to cause increases in Arctic precipitation, causing increase in snow pack, making

feeding difficult.

Who else loses?

Who Benefits from Inaction?• In general, natural resource extraction and refining; new areas open to exploitation•Construction companies;

anyone who can make a profit following coastal disasters• Oppressive governments

• Some warming has already occurred; more will likely already occur regardless of anything else

• The amount of future warming will depend on a number of different forcings, one of which is human-made emissions

• With regard to predictions of future emissions and warming, it is useful to speak in terms of scenarios

• See “Summary for Policymakers” at WWW.IPCC.CH – last page

Prediction Scenarios

• Human population distribution– Large numbers near coasts or major rivers

• Coastal ecosystem disruption• Global dilemma– International cooperation required at a time of

serious divisions– Mitigating climate change offers a means of

encouraging cooperation on other issues

Large-scale Implicationsof Sea Level Rise