It was first recognized in the last century that human activities could have an important effect on the Earth's climate. Not until the early 1960s, however, was there convincing evidence that human activities were indeed changing the chemical composition of the global atmosphere. In 1964, the President's Science Advisory Council first brought the issue to the attention of the U.S. Government. In the late 1960s and throughout the 1970s, an initial set of computer model simulations were generated to predict changes in temperature and precipitation that could occur, given the continuing trend in increasing levels of human emissions of greenhouse gases to the atmosphere. In the late 1970s and early 1980s, the National Academy of Sciences convened several panels and committees which reported that a doubling of the atmosphere's carbon dioxide concentration could potentially raise the global average temperature by 1.5 to 4.5°C (about 2.5 to 8°F) and shift rainbelts poleward. In 1988, after significant national and international research efforts were initiated to further the scientific understanding of the issue, the Intergovernmental Panel on Climate Change, composed of hundreds of scientists from more than 50 countries, assumed responsibility for conducting international assessments on climate change and its consequences. To date, the IPCC has produced a series of reports (1990, 1992, 1994, and a 1995 report is in progress).
In parallel with these efforts to synthesize scientific information, national and international research programs have been established to improve predictive understanding of the Earth system and to provide the broader information base needed by decisionmakers to consider whether and how to respond. Building upon the knowledge base developed by the nation's basic research program in Earth sciences, an increasing array of research activities was begun in the late 1970s and 1980s. To further enhance the effort, President Bush established the interagency U.S. Global Change Research Program in 1989, to coordinate and strengthen these activities. Congress enacted a statutory mandate for the USGCRP in 1990. The USGCRP currently conducts a comprehensive research effort involving observation and data management, field studies to improve understanding of climate processes, integrated modeling and prediction, and investigation and assessment of the potential environmental and socio-economic consequences of global environmental change.
In the fall of 1994, the interagency Subcommittee on Global Change Research arranged for the special Forum on Global Change Modeling to provide an indication of the state of current progress in improving understanding of global change and to provide direction for future research. This Forum served as a means of bringing together a representative set of scientists to develop a consensus statement on the credibility of global model estimates of future climatic change.
This report is the agreed-upon statement from the participants at the meeting, including revisions and responses based on a wider review by the scientific community. We would like to express our gratitude to the participants for their commitment to this effort. We hope to update the following statement from the Forum periodically as new scientific progress is made through national and international research efforts.
Robert C. Corell, Chair
Subcommittee on Global Change Research
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