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. National Assessment

Emissions ScenariosRadiative Forcing               

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.

Global Temperature      US Temperature

Global Precipitation     US Precipitation 

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.

Minimum Temperature      Maximum Temperature      Precipitation


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.

Observed Temperature      Canadian Temperature       Hadley Temperature

Observed Precipitation     Canadian Precipitation     Hadley Precipitation