Z-Z. Hu, S.I. Kuzmina, L. Bengtsson, and D.M. Holland, 2003:
Mean and uncertainty of Arctic sea-ice change and their connection with Arctic climate change in CMIP2 simulations,
COLA Technical Report No. 152, Center for Ocean-Atmosphere-Land Studies, Calverton, Maryland USA, 31 pp.


In this work, we analyze the two-dimensional distribution of mean and uncertainty of Arctic sea-ice and climate change at time of CO2 doubling and their connection using the simulations of the second phase of the Coupled Model Intercomparison Project (CMIP2). Comparison with observations shows that the ensemble mean of CMIP2 models simulates the observed sea-ice climatology reasonable well.  Arctic surface warming at the time of CO2 doubling is not evenly-distributed and ranges from 1 C to 5 C.  The intermodel spread is pronounced in the Arctic Ocean, particularly
in the Barents Sea. Reduction of sea-ice thickness is in the range 0.3-1.8 m and mainly appears in the Greenland-Barents Seas. Meanwhile, sea-ice concentrations decrease more than 10% in  most regions of the Arctic Ocean. The sensitivity of Arctic surface air temperature change with respect to sea-ice area change is model dependent. For some models, the sensitivity is different even in different periods of the transient integration.
Values of the sensitivity vary from -2.0 to -0.5 C/10^6 km^2 for most CMIP2 models. Furthermore, colder (warmer) Arctic climate may favor higher (lower) sensitivity.

Simulated mean and intermodel spread patterns of surface air temperature change are similar to those of sea-ice thickness and sea level pressure changes, implying that the mean and uncertainty of projected Arctic climate change may be largely determined by the interaction between sea-ice and the atmosphere. Both sea-ice thickness and sea-ice concentration are sensitive to the increase in greenhouse gas concentrations, and are connected with surface air temperature and sea level pressure changes in the Arctic. The average of all model simulations indicates that a positive phase of the Arctic Oscillation is stronger and/or occurs more often at the time of CO2 doubling. Both the mean and intermodel spread patterns show considerable differences between models with and without flux adjustment in some regions.

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