arctic sea ice cover september 2005 nasa. sea ice extent march 2006 maximum september 2006 minimum...
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ARCTIC SEA ICE COVERSeptember 2005
NASA
SEA ICE EXTENTMarch 2006
MaximumSeptember 2006
Minimum
NEW RECORD!
2006: At or near record minimum in summer and winter
SEA ICE EXTENT
Max. Extent: 2.5% per decadeMin. Extent: 8.9% per decade
1979-2006: Decreasing trend
UCAR, Holland et al., 2006
The Road Ahead?
Ice-free summers in foreseeable future
SEA ICE COVERaka ‘The Great Integrator’
Ocean heat flux
Solar radiation
THERMODYNAMICSIce grow, melt and decay
Ocean stress
Wind stress
DYNAMICSIce motion
Reflects impact of atmospheric and oceanic forcing
Arctic Oscillation (AO)Two Dominant Regimes
• Colder winter temperatures• Strong Beaufort Gyre
• Warmer winter temperatures• Transpolar Drift Stream
sweeps ice out of Arctic Ocean
Negative AO Positive AO
ICEGAINS
ICELOSES
Atmospheric Oscillation (AO)
Strong positive pattern dominated from 1989 – 1996Favors loss of sea ice
More neutral pattern from 2000 - 2006Opportunity for recovery
Arctic Surface Air Temperature1900- 2006
Arctic-wide, annual averaged SAT anomalies (60 – 90°N) over land
1980-present: Warming trend
Warming: Arctic trend consistent with global trend
• March-May temperature anomaly composites • Relative to a 1968-1996 base period
SURFACE TEMPERATURE
Despite shift, positive (warm) anomalies remain over the entire Arctic
Southeastern Bering Sea continental shelf mooring
OCEANTemperature
2006: Significant cooling compared to previous 6-years
• Anomalies relative to EWG climatology (1950-1980s)
• NPEO surveys & J-CAD
Morison et al., 2006a
OCEANNorth Pole Region
2000-2005:
Relaxation to near pre-1990 climatology
2000
2005
Salinity Temperature
Temperature & Salinity
2006 Arctic Report CardSea Ice Cover
• Arctic Oscillation
• Surface Temperature
• Ocean Temperature
Why continued decrease in extent?
Absorbedsunlight Lower albedo
Melting
Absorbedsunlight
Melting
Lower albedoAbsorbedsunlight
Melting
Lower albedo
+
++Positive
Feedback Cycle
Rigor and Wallace, 2004
Sep 2006
Canada
Alaska
Russia
Older, thicker ice
Sep 1987
Younger, thinner ice
SEA ICE AGE(Think thickness)
1988-1990: Precipitous decrease in thick ice
OW 0 1 2 3 4 5 6 8 10+ Years
Age:
PERENNIAL SEA ICEOlder, thicker ice
1950 1960 1970 1980 1990 2000 20102.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Year
Modeled QuikScat
Per
enni
al ic
e ar
ea (
106 k
m2 )
Rigor & Nghiem
Significant decrease in older ice
Strong & Persistent Positive AO
Sea ice cover susceptible to loss
Strong & PersistentPositive AO
(Less sea ice)
+Rising GlobalTemperature
Absorbedsunlight Lower albedo
Melting
+
++
Strong Positive Feedback Cycle
+
Confluence of Events…
State of the Arctic Sea Ice Cover
Summary• System under stress• Destabilization?
Arctic Oscillations Index
Through mid - 1990s:AO index effective predictorof trends in sea icecharacteristics
1989-1996: Strong positive AO2000s:
• 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
Will system rebound?or
Has a ‘tipping’ point been reached?
International Polar Year
http://www.ipy.org/
IMPACT OF IPY2007-2008
June 2006
34 Platforms Reporting
May 2007
>150 Platforms Reporting