I worked as a project scientist for the U.S. National Assessment
of the potential consequences of climate variability and
change. I served as the climate
scenarios coordinator for the National Assessment Working Group and the
National Assessment Coordination Office in Washington D C. I was located
with the Climate and Global
Dynamics Division at the National
Center for Atmospheric Research in Boulder, Colorado. The simulations
used in the U.S. National Assessment all involve coupled atmosphere-ocean
general circulation models (GCMs) with transient greenhouse gases and sulfate
aerosols. These simulations include the CCCma CGCM1 (Canadian) model and the Hadley HADCM2 model
(British). Data from the MPI/DKRZ ECHAM4/OPYC3 (German) model, using similar emissions
scenarios, are also available. NCAR has completed several new simulations
that include a) multiple greenhouse gases b) more realistic sulfate emissions
scenario c) actual sulfate chemistry model and a d) coupled atmosphere-ocean
GCM that is not flux-corrected. The VEMAP project has downscaled the
historical station data from NOAA's National Climatic Data Center's U.S.
Historical Climate Network ( HCN) and other cooperative network stations, plus USFS and
BLM SnoTel stations for high elevation precipitation to account for elevational
effects. The future GCM data is applied to this data set to produce a
downscaled version of the GCM output.
Emissions Scenarios: These figures are the equivalent CO2 concentrations and
sulfate emissions that were used to force the GCM simulations used in the U.S.
Intermodel Comparisons: These figures are the global and U.S. temperature and precipitation trends for several GCMs using an approximately 1% increase in greenhouse gases plus sulfate aerosols.
Time Series: These figures are the minimum temperature, maximum temperature, and precipitation time series averaged over the U.S. for the HCN and VEMAP-processed data.
Maps: These figures are the temperature and precipitation trends observed over the 20th century and projected for the 21st century by the Canadian and Hadley models.