Alaska Gov. Sarah Palin says the state will sue to challenge the listing of polar bears as a threatened species under the Endangered Species Act.
Palin on Wednesday said there is insufficient evidence to support the decision U.S. Interior Secretary Dirk Kempthorne made last week.
Kempthorne says the best available science indicates that the bears' primary habitat, sea ice, was shrinking and likely to further recede. Palin says polar bears are well managed and that their numbers have dramatically increased over 30 years.
Conservation groups say the increase is due to measures that halted over-hunting but that populations are likely to crash as summer sea ice diminishes.