Rick S. Piltz, a longtime climate-policy analyst who exposed how top-level officials in the George W. Bush administration edited scientific reports to minimize the link between human activity and climate change, has died. Piltz, who was 71, died of bladder cancer October 18 at a hospice in Washington. Piltz held a senior post with the U.S. Global Change Research Program, through which U.S. government agencies coordinate support for climate research, for a decade. He quit in March 2005, citing frustration with the Bush administration's efforts to change the testimony of federal officials and the reports they submitted documenting the impact of global warming. He gave a trove of documents to the New York Times for publication in June 2005. He later started the group Climate Science Watch.