Polar Climate Change and the Arctic Oscillation in CCSM3 IPCC
Scenario Simulations
June22 2006
Haiyan Teng
NCAR/CGD
H. Teng, W. M. Washington, G. A. Meehl, L.E. Buja and G. W. Strand, 2006: Twenty-first century Arctic climate change in the CCSM3 IPCC scenario simulations, Climate Dynamics
Sea Ice Extent Sea Ice Concentration
http://nsidc.org/data/seaice_index/
Overland and Wang, 2005: The Arctic climate paradox: Therecent decrease of the Arctic Oscillation
Moritz et al. (Science 2002) review “Dynamics of recentclimate change in the Arctic”
TAS EOF1
TAS EOF2
SLP EOF1
1870-2099
PDF of the AO index (SLP EOF1)
Red: 21st centuryBlack:20th centuryA2
A1B
B1
Conclusions
• The AO is the dominant mode in the wintertime atmosphere and sea ice variability in the 1870-1999 historical runs.
• The AO shifts to the positive phase in response to anthropogenic forcing in the 21st century but the simulated AO trends are smaller than the observed.
• The AO plays a secondary role (<10% of the total variance) in the 21st century while 50%-70% of the total variances are explained by the warming trend.
Surface Temperature EOF1
Surface temperature EOF2
Sea level pressure EOF1
Questions
• How does the AO respond to the anthropogenic forcing?
• Thinning of current Arctic sea ice: triggered by the early 1990s’ positive AO?
• Climate variability under a warming trend