Polar bears are threatened with extinction in many areas because of the melting of their sea ice habitat. The groups say greenhouse gas emissions have led to rapid melting in the Arctic.
Interior Secretary Dirk Kempthorne, facing a court deadline because of the groups' earlier lawsuit, had announced Wednesday that polar bears would be listed as threatened under the Endangered Species Act.
Among the steps he proposed to help them were increasing research and working with Canada to help the bears survive in the wild. But he rejected the addition of broad steps to reduce greenhouse gases, saying he would not allow the Endangered Species Act to be "misused" to regulate global climate change.
Kassie Siegel, climate director for the CBD, said the administration's proposal "violates both logic and the law" because it did not address the primary threat to polar bears. The listing of polar bears under the law is significant, she acknowledged, but the groups want them classified as endangered, a more serious category than threatened.
Joining in the court case were Greenpeace and the Natural Resources Defense Council. They announced their new federal court filing on Tuesday. A message left with the Department of the Interior in Washington was not immediately returned.
Kempthorne said Americans deserve an honest assessment of the costs and benefits of reducing greenhouse gas emissions. Quoting President Bush, he said the decision should not be left to "unelected regulators and judges" who enforce the Endangered Species Act. He also said any real solution requires action by all major world economies.