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Date: Oct. 13, 2003
Contacts: Bill Kearney, Director of Media Relations
Christian Dobbins, Media Relations Assistant
Office of News and Public Information
202-334-2138; e-mail <>


Publication Announcement

U.S. Should Pursue Additional Research on Weather Modification

For the last 60 years, technologies to influence weather have been used in attempts to alleviate droughts or the effects of hazardous storms. Today, operational weather-modification programs exist in more than 24 countries, and in 2001 at least 66 efforts to alter the weather were conducted in 10 states across the United States. But research on weather modification has dwindled, leaving critical uncertainties and knowledge gaps. In the late 1970s, the United States invested more than $20 million a year in weather-modification research but now spends less than $500,000 annually, and only a handful of research programs exist worldwide.

Atmospheric science has made significant advances over the last 30 years, improving our ability to observe the weather, accumulate and assess vast quantities of data, and simulate natural processes using sophisticated mathematical models. But because weather-modification research has not kept pace, these advances have not been applied in any coherent or sustained way to our understanding of whether, how, and to what extent we can influence weather, says a new report from the National Academies' National Research Council. The report calls for a coordinated, sustained national program to answer fundamental questions about basic atmospheric processes and address other issues that are impeding progress in weather modification, before any large-scale operational effort is mounted.

There is ample evidence that "seeding" a cloud with a chemical agent -- such as silver iodide, which could form ice crystals that may fall as rain -- can modify the cloud's development and precipitation. However, scientists are still unable to confirm that these induced changes result in verifiable, repeatable changes in rainfall, hail fall, and snowfall on the ground, according to the report.

Nearly 2 billion people face severe water shortages, and this number is projected to increase to over 3 billion during the next 25 years. While intentional weather modification is used in the hope of improving quality of life, there is ample evidence that other human activities, such as those causing industrial air pollution, alter atmospheric processes on a local and global scale, usually in a negative way. Although many of the fundamental processes related to both intentional and unintentional changes in the atmosphere are the same, the scientific community has largely failed to take advantage of this fact in its research on weather modification, the report notes.

The report is the latest in a series of assessments of weather modification carried out by the National Academies; all of these reports have concluded that the science underlying attempts to modify the weather is too weak to prove that such attempts actually produce results. Since the last Academy report on the subject in 1973, however, there have been significant advances in observational, computational, and statistical technologies, allowing a more thorough investigation of the complex processes in the atmosphere, the new report says. Still, little of this collective power has been applied in any coherent way to weather modification.

The national program recommended in the report would conduct research on cloud and precipitation microphysics, cloud dynamics, cloud modeling, and cloud seeding. The program would focus on using new tools to carry out experiments, working to improve models of clouds and precipitation, and developing partnerships among research groups and select operational programs. The new technologies include millimeter-wave cloud radar, which has high sensitivity and resolution, enabling researchers to observe the fine-scale structure of clouds, snowstorms, and rainfall. This radar also holds great promise for revealing the physical transformations in the seeded regions of clouds, the report says.

The report was sponsored by the National Oceanic and Atmospheric Administration. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides science and technology advice under a congressional charter. A committee roster follows.

Copies of Critical Issues in Weather Modification Research will be available later this fall from the National Academies Press; tel. 202-334-3313 or 1-800-624-6242 or order on the Internet at Reporters may obtain a pre-publication copy from the Office of News and Public Information (contacts listed above).

[ This announcement and the report are available at ]

National Research Council
Division on Earth and Life Studies
Board on Atmospheric Sciences and Climate

Committee on the Status and Future Directions in
U.S. Weather Modification Research and Operations

Michael Garstang (chair)
Distinguished Emeritus Research Professor
University of Virginia, and
Senior Scientist
Simpson Weather Associates

Roscoe R. Braham Jr.
Professor and Scholar-in-Residence
Department of Marine, Earth, and Atmospheric Sciences
North Carolina State University

Roelof T. Bruintjes
Project Scientist III
Research Applications Program
National Center for Atmospheric Research
Boulder, Colo.

Steven F. Clifford1
Research Associate
Cooperative Institute for Research in Environmental Sciences
University of Colorado

Ross N. Hoffman
Vice President for Prediction and Radiation Studies
Atmospheric & Environmental Research Inc.
Lexington, Mass.

Douglas K. Lilly2
Professor Emeritus
University of Oklahoma

Robert J. Serafin1
Director Emeritus
National Center for Atmospheric Research
Boulder, Colo.

Paul Try
Senior Vice President and Program Manager
Science and Technology Corp.
Silver Spring, Md.

Johannes Verlinde
Associate Professor
Department of Meteorology
Pennsylvania State University
University Park


Laurie Geller
Study Director (until July 2003)

Julie Demuth
Study Director (since March 2003)

1 Member, National Academy of Engineering
2 Member, National Academy of Sciences