New Paper Available
"Arctic Climate Change: Observed and Modelled Temperature and Sea-ice
Variability"
Nansen Environmental and Remote Sensing Center
The paper can be downloaded from the project page "Arctic Ice Cover
Simulation Experiment" (AICSEX) available at:
http://www.nersc.no/AICSEX/tellus_omj.pdf
The Nansen Center Technical Report No. 218 (2002) "Arctic Climate
Change: Observed and Modelled Temperature and Sea-ice Variability" by
Johannessen et al. is now published in Tellus, Volume 56A, No. 4,
August, 2004.
ABSTRACT
Changes apparent in the arctic climate system in recent years require
evaluation in a century-scale perspective in order to assess the
Arctic's response to increasing anthropogenic greenhouse-gas forcing.
Here, a new set of century and multidecadal-scale observational data of
surface air temperature (SAT) and sea ice is used in combination with
ECHAM4 and HadCM3 coupled atmosphere-ice-ocean global model simulations
in order to better determine and understand arctic climate variability.
We show that two pronounced twentieth-century warming events, both
amplified in the Arctic, were linked to sea-ice variability. SAT
observations and model simulations indicate that the nature of the
arctic warming in the last two decades is distinct from the early
twentieth-century warm period. It is suggested strongly that the earlier
warming was natural internal climate-system variability, whereas the
recent SAT changes are a response to anthropogenic forcing. The area of
arctic sea ice is furthermore observed to have decreased approximately
800,000 square km (7.4%) in the past quarter century, with record-low
summer ice coverage in September 2002. A set of model predictions is
used to quantify changes in the ice cover through the twenty-first
century, with greater reductions expected in summer than winter. In
summer, a predominantly sea-ice-free Arctic is predicted for the end of
this century.
The paper can be downloaded from the project page "Arctic Ice Cover
Simulation Experiment" (AICSEX) available at:
http://www.nersc.no/AICSEX/tellus_omj.pdf