Introduction

Abstract:

Climate modeling has developed like other areas of science and engineering over the last fifty years to become a very useful tool for research and prediction of future changes in our global environment. The most recent Intergovernmental Panel on Climate Change Assessment Report (IPCC assessment) has convinced most climate scientists that humankind is changing the earth’s climate and that significant global warming is already taking place.

Some scientists are skeptical of the IPCC view and think the observed changes result from natural climate variability or other causes. A brief review of recently observed 20th century climate change will be presented and compared with climate model simulations. These computer simulations are extended into the 21st century and beyond in preparation for the next IPCC assessment. A brief description of what is in present day climate models will be given with an emphasis on the physical and computational aspects. Computer simulations and animations of present climate and future climate change will also be shown using low and high carbon emission scenarios.

Finally, at the end there will be a discussion of the scientific uncertainties and societal impacts along with an analysis of policy options including possible geoengineering of the climate system. How the United States coordinates global change research will also be discussed.