Merchants of Doubt is a 2010 non-fiction book by American historians of science Naomi Oreskes and Erik M. Conway. It identifies parallels between the global warming controversy and earlier controversies over tobacco smoking, acid rain, DDT, and the hole in the ozone layer. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached, was the basic strategy of those opposing action. In particular, they say that Fred Seitz, Fred Singer, and a few other contrarian scientists joined forces with conservative think tanks and private corporations to challenge the scientific consensus on many contemporary issues.