Polar Climate Change and the Arctic Oscillation in CCSM3 IPCC Scenario Simulations

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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

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Sea Ice Concentration
Sea Ice Extent
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Moritz et al. (Science 2002) review Dynamics of
recent climate change in the Arctic
http//nsidc.org/data/seaice_index/
Overland and Wang, 2005 The Arctic climate
paradox The recent decrease of the Arctic
Oscillation
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1870-2099
TAS EOF1
TAS EOF2
SLP EOF1
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PDF of the AO index (SLP EOF1)
Red 21st century Black20th century
A2
A1B
B1
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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 (lt10 of the total
  variance) in the 21st century while 50-70 of
  the total variances are explained by the warming
  trend.

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Surface Temperature EOF1
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Surface temperature EOF2
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Sea level pressure EOF1
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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