A rise in sea levels and other changes fueled by global warming threaten roads, rail lines, ports, airports and other important infrastructure, and policy makers and planners should be acting now to avoid or mitigate their effects, according to new government reports. Backstory With Cornelia Dean (mp3)While increased heat and "intense precipitation events' threaten these structures, the greatest and most immediate potential impact is coastal flooding, according to one of the reports, by an expert panel convened by the National Research Council, the research arm of the National Academy of Sciences. Another study, a multiagency effort led by the Environmental Protection Agency, sounds a similar warning on infrastructure but adds that natural features like beaches, wetlands and fresh-water supplies are also threatened by encroaching saltwater. The reports are not the first to point out that rising seas, inevitable in a warming world, are a major threat. In a report last September, the Miami-Dade County Climate Change Task Force noted that a two-foot rise by the year 2100, the prediction of the United Nation's Intergovernmental Panel on Climate Change, "would make life in South Florida very difficult for everyone.' But the new reports offer detailed assessments of vulnerability in the relatively near term. Both note that coastal areas are thickly populated, economically important and gaining people and investment by the day, even as scientific knowledge of the risks they face increases. Use of this knowledge by policy makers and planners is "inadequate,' the academy panel said. "It's time for the transportation people to put these things into their thought processes,' Henry G. Schwartz Jr., the chairman of the Research Council panel, said in an interview. The 218-page academy report was issued Tuesday, and is available at nationalacademies.org. Noting that 60,000 miles of coastal highways are already subject to periodic flooding, the academy panel called for policy makers to survey vulnerable areas