Scientists at Stanford University's biological sciences department are staking somewhat more than their professional reputations on the belief that their concerns about the environment are well-founded--about $15,000 more. The scientists responded to a challenge from Julian Simon--a University of Maryland professor of business administration who has long asserted that environmental trends are positive and "doomsaying environmentalists" are wrong--in the San Francisco Chronicle (Op- ed, May 12, 1995, page A25). Simon called on environmentalists to bet with him on whether "any trend pertaining to material human welfare" will get worse in the future. The Stanford scientists, ecologist Paul R. Ehrlich and climatologist Stephen Schneider, responded in an op-ed essay in the Chronicle on May 15 (page A23) with an offer to wager $1,000 on each of 15 current trends, betting that each will get worse over a 10-year stretch in the future. Among the trends they bet would continue were: rising...