Transcript Cryospherex

• 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
• “Canary in the coal
mine”
Perito Moreno glacier
Glacier National Park,
Argentina.
– 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.
Components
• 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
• 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
• 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 19612004; 0.77 SLE 19912004; trending higher
• 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
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:
An 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)
– Approximately 3,000
years in age
– In 2002 it began to
break up
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
• 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
• 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
Increases in temperature
encourage mosquito harassment
Paradoxically, warming is predicted to
cause increases in Arctic precipitation,
causing increase in snow pack, making
feeding difficult.
• 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
• 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