In 1990 Singer set up the Science & Environmental Policy Project (SEPP) to argue against preventive measures against global warming. After the 1991 United Nations Conference on Environment and Development, the Earth Summit, Singer started writing and speaking out to cast doubt on the science. He predicted disastrous economic damage from any restrictions on fossil fuel use, and argued that the natural world and its weather patterns are complex and ill-understood, and that little is known about the dynamics of heat exchange from the oceans to the atmosphere, or the role of clouds. As the scientific consensus grew, he continued to argue from a skeptical position. He has repeatedly criticized the climate models that predict global warming. In 1994 he compared model results to observed temperatures and found that the predicted temperatures for 1950–1980 deviated from the temperatures that had actually occurred, from which he concluded in his regular column in "The Washington Times"—with the headline that day "Climate Claims Wither under the Luminous Lights of Science"—that climate models are faulty. In 2007 he collaborated on a study that found tropospheric temperature trends of "Climate of the 20th Century" models differed from satellite observations by twice the model mean uncertainty.