The U.S. nuclear weapons stockpile is aging and, according to the government, the older weapons are ready to be retired. New weapons are in the planning stages, but bans on certain forms of weapons testing leave weapons scientists with a challenge: is it possible to build a nuclear bomb and be so certain it will work that physical tests will never be necessary? Join us in this hour of Science Friday for a look at the 'Reliable Replacement Warhead' program and the development of the next generation of nuclear weapons.

Plus, new research published this week in the journal Science says that global warming may be causing more intense wildfires in the western United States. The researchers found that increases in large wildfire activity in the western US over the past 25 years is 'strongly associated with increased spring and summer temperatures and an earlier spring snowmelt.' We'll talk to one of the authors of the report about the findings.

Call in with your questions and comments at 1-800-989-8255 (2-3 Eastern). Teachers, find more information about using Science Friday as a classroom resource in the Kids' Connection.

Guests:
Geoff Brumfiel
Washington Correspondent
Nature Magazine
Washington, DC

Robert W. Nelson
Senior Scientist, Union of Concerned Scientists
Visiting Member of the Research Staff, Program on Science and Global Security
Princeton University
Princeton, New Jersey

Ambassador C. Paul Robinson
Head, U.S. Delegation to the Nuclear Testing Talks (1988-1990)
Former Director, Sandia National Laboratories
Albuquerque, New Mexico

*****************

Anthony Westerling
Assistant Project Scientist, Climate Research Division
Scripps Institution of Oceanography
University of California, San Diego
La Jolla, California
Faculty member, University of California, Merced
Merced, California

Books/Articles Discussed:

Nuclear weapons: The next nuke (Nature, 442, 18-21, July 6 2006)

"Warming and Earlier Spring Increases Western U.S. Forest Wildfire Activity," by A.L. Westerling and colleagues. Science, July 7 2006.

(find books discussed on previous broadcasts)

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This segment produced by Karin Vergoth