ARCTIC SEA ICE COVER

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ARCTIC SEA ICE COVER
September 2005
NASA
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SEA ICE EXTENT
2006 At or near record minimum in summer and
winter
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SEA ICE EXTENT
Max. Extent 2.5 per decade Min. Extent 8.9
per decade
1979-2006 Decreasing trend
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The Road Ahead?
UCAR, Holland et al., 2006
Ice-free summers in foreseeable future
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SEA ICE COVER aka The Great Integrator
Reflects impact of atmospheric and oceanic forcing
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Arctic Oscillation (AO)Two Dominant Regimes
Negative AO
Positive AO
ICE LOSES
ICE GAINS

• Colder winter temperatures
• Strong Beaufort Gyre

• Warmer winter temperatures
• Transpolar Drift Stream sweeps ice out of
  Arctic Ocean

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Atmospheric Oscillation (AO)
Strong positive pattern dominated from 1989
1996 Favors loss of sea ice
More neutral pattern from 2000 -
2006 Opportunity for recovery
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Arctic Surface Air Temperature1900- 2006
Arctic-wide, annual averaged SAT anomalies (60
90N) over land
1980-present Warming trend
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Warming Arctic trend consistent with global trend
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SURFACE TEMPERATURE

• March-May temperature anomaly composites
• Relative to a 1968-1996 base period

Despite shift, positive (warm) anomalies remain
over the entire Arctic
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OCEANTemperature
Southeastern Bering Sea continental shelf mooring
2006 Significant cooling compared to previous
6-years
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North Pole Region
OCEAN
Salinity
Temperature
Temperature Salinity
2000

• Anomalies relative to EWG climatology
  (1950-1980s)
• NPEO surveys J-CAD 

2000-2005 Relaxation to near pre-1990
climatology
2005
Morison et al., 2006a
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2006 Arctic Report CardSea Ice Cover

• Arctic Oscillation
• Surface Temperature
• Ocean Temperature

Why continued decrease in extent?
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Ice albedo feedback
Melting
Melting
Melting


Positive Feedback Cycle
Absorbed sunlight
Absorbed sunlight
Lower albedo
Absorbed sunlight
Lower albedo
Lower albedo

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SEA ICE AGE(Think thickness)
Sep 1987
Russia
Older, thicker ice
Alaska
Canada
Sep 2006
Younger, thinner ice
1988-1990 Precipitous decrease in thick ice
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PERENNIAL SEA ICEOlder, thicker ice
Strong Persistent Positive AO
Rigor Nghiem
Significant decrease in older ice
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Sea ice cover susceptible to loss
Confluence of Events


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State of the Arctic Sea Ice Cover

• Summary
• System under stress
• Destabilization?

Will system rebound? or Has a tipping point
been reached?

• Through mid - 1990s
• AO index effective predictor
• of trends in sea ice
• characteristics

• 1989-1996 Strong positive AO
• 2000s
• AO shifted back to more neutral state
• Sea ice not following suit
• Continued reduction in sea ice extent
• Continued reduction in amount of older, thicker
  ice

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International Polar Year
http//www.ipy.org/
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IMPACT OF IPY2007-2008