A case filed in San Francisco, California, with the Friends of the Earth, Greenpeace and the cities of Boulder, Colorado, and Oakland, California, as plaintiffs, seeks to force two government agencies to assess the total impact on climate of the projects they finance. Litigation may soon be the weapon of choice for those concerned about human-induced global warming. In the San Francisco case, the plaintiffs charge that the Overseas Private Investment Corporation (OPIC) and the Export-Import Bank of the United States (ExIm) have provided $32 billion in loans, insurance and loan guarantees for oil pipelines, oil drilling and other fossil-fuel endeavors that will ultimately result in the emission of 32 billion tons of carbon dioxide over the life of the projects. The lawsuit does not attempt to cancel ongoing projects but asks only that OPIC and ExIm determine the "cumulative impact" on the climate of every future project. Such a review, asserts Jon Sohn of Friends of the Earth, is required by the National Environmental Policy Act. The plaintiffs are confronted with many hurdles. They will have to demonstrate that they face harm from global warming and, in particular, from the agencies' actions. The cities contend that their water supplies are in jeopardy. Scientific uncertainties over such claims can be partly overcome by aggregating harm done over a large span of space and time, contends David Grossman, a recent graduate of Yale Law School and now a law clerk in Anchorage. In a paper to be published in the 'Columbia Journal of Environmental Law,' Grossman argues that tort litigation over global warming--in which communities or states seek damages from oil companies, electric utilities and automobile manufacturers--is entirely feasible. INSET: WHOSE FAULT IS IT ANYWAY?.