The Endangered Species Act (ESA) provides a program for the conservation of threatened and endangered plants and animals and the habitats in which they are found. The U.S. Fish and Wildlife Service (FWS) of the Department of the Interior maintains a worldwide list which, as of Feb. 20, 2008, included 1574 endangered species (599 are plants) and 351 threatened species (148 are plants). Species include birds, insects, fish, reptiles, mammals, crustaceans, flowers, grasses, and trees. Anyone can petition FWS to include a species on this list. The law requires federal agencies, in consultation with the U.S. Fish and Wildlife Service and/or the U.S. National Oceanic and Atmospheric Administration Fisheries Service, to ensure that actions they authorize, fund, or carry out are not likely to jeopardize the continued existence of any listed species or result in the destruction or adverse modification of designated critical habitat of such species. The law also prohibits any action that causes a "taking" of any listed species of endangered fish or wildlife. Likewise, import, export, interstate, and foreign commerce of listed species are all generally prohibited.

This article was published in Nature and summarized the presentations of a six-day symposium held 3-8 July 1995 on Climate Variability and Forcing over the past mellennium. Our present climate is unusually warm, and the pattern of warming over the past century strongly suggests an anthropogenic influence from greenhouse gas and sulphate aerosols. That was the message emerging from a week-long symposium examining climate variability over the past 1,000 years, which brought together results from a growing array of observational techniques, analyses of natural records and model results.

The United States Clean Air Act is legislation authorizing the Environmental Protection Agency to control air pollutiants on a national level.