More specifically, the accuracy of the models’ predictions is limited by (1) incomplete or inadequate representations of the processes affecting climate and (2) insufficient computer power. Global Change Research Program’s fiscal year 1995 research programs are summarized in appendix III. Federal Expenditures for GCMs

Five federal agencies reported spending an estimated $122.6 million during fiscal years 1992 through 1994 to fund modeling activities to improve predictions of the future climate. Conclusions

Although the accuracy of general circulation models’ estimates of climatic change has improved over the past decade, these estimates are still limited by incomplete and inaccurate representations of the processes affecting climate and by insufficient computer power. We have responded to the agencies’ comments by adding information about ongoing research to overcome the models’ scientific and technical limitations and about recent positive results achieved with the models. Objectives, Scope, and Methodology

The Ranking Minority Member of the House Committee on Commerce asked us to review the factors that affect the accuracy of GCMs’ estimates of future climatic changes and determine the costs of federally funded GCMs for fiscal years 1992 through 1994. 1. 2. 3.
Why GAO Did This Study

Pursuant to congressional request, GAO reviewed the accuracy of general circulation models (GCM) in forecasting global warming trends, focusing on the: (1) factors limiting the accuracy of GCM estimates of future climatic changes; and (2) federal expenditures for GCM for fiscal years (FY) 1992 through 1994.

What GAO Found

GAO found that: (1) although GCM have improved their ability to predict future climatic changes over the last decade, their estimates are still limited by their incomplete or inaccurate representations of climate-affecting processes and by insufficient computer power; (2) scientists do not fully understand how the climate system responds to potentially important physical, chemical, and biological processes; (3) the lack of computer power requires scientists to use simplified assumptions and structures that increase the uncertainty of the models' predictions; (4) scientists are conducting research to overcome the limitations of the computer models; and (5) five federal agencies spent about $122.6 million for various global modeling projects, which represented about 3 percent of the global change research program's budget for FY 1992 through 1994.