The United States Fish and Wildlife Service (FWS) (defendant) decided to list polar bears as threatened under the Endangered Species Act (Act), 16 U.S.C. §§ 1531 et seq. The Act defined a threatened species as one that was likely to become endangered within the “foreseeable future.” The FWS used the best available climate models to define the foreseeable future as 45 years. The FWS then issued a listing rule that categorized polar bears as threatened, citing three main considerations: (1) the polar bears’ dependence on sea ice for survival, (2) the decline in sea ice, and (3) the continued sea-ice decline due to climate change. These considerations resulted from the FWS’s review of published studies, observations, models, and reports from sources that included the Intergovernmental Panel on Climate Change (IPCC). Although the FWS considered 19 different polar-bear populations, the FWS found that the populations were not sufficiently distinguishable to be divided into distinct segments. A number of industry groups, environmental organizations, and states (plaintiffs) challenged the listing rule as either overly restrictive or insufficiently protective. The plaintiffs’ challenges were consolidated before the United States District Court for the District of Columbia. The plaintiffs argued that the FWS had misinterpreted and misapplied the record regarding its decisions on the distinct population segments and the 45-year foreseeability period. The district court rejected the plaintiffs’ challenges to the listing rule and granted summary judgment to the FWS. The plaintiffs appealed.