The Department of the Interior explains:

Secretary of the Interior Dirk Kempthorne today announced that he is accepting the recommendation of U.S. Fish and Wildlife Service Director Dale Hall to list the polar bear as a threatened species under the Endangered Species Act (ESA). The listing is based on the best available science, which shows that loss of sea ice threatens and will likely continue to threaten polar bear habitat. This loss of habitat puts polar bears at risk of becoming endangered in the foreseeable future, the standard established by the ESA for designating a threatened species.

The logic here is fairly tortured. Global warming threatens polar bears, and the US government acknowledges that it has to take steps to control that threat. But since every other country hasn't taken steps to control carbon dioxide emissions, no steps can be taken to block that threat.

It isn't that Kempthorne is wrong to say that "The ESA is not the right tool to set U.S. climate policy," the problem is that all other paths to setting climate policy have been closed off. When EPA staffers recommended allowing California to regulate carbon dioxide, political officials overruled them, denying California's request.

Similarly, when the Supreme Court ruled that the EPA could not duck a lawsuit demanding regulations of carbon dioxide, the administration responded by scuttling its internal rulemaking process. Last December, EPA administrator Stephen Johnson "ordered staff to stop work on the federal greenhouse gas proposal, said two sources inside and outside the agency."

In that Supreme Court case, the administration argued that ongoing international negotiations and actions in other governmental agencies precluded the EPA from taking action on carbon emissions. As I said at the time, "The [Court's] majority ruled that the agency could not refuse to regulate carbon dioxide simply because of policy objections, or because of unrelated actions being taken (or not taken) by other parts of the government."

Addressing claims that ongoing action in the international arena, Congress and other agencies mitigated EPA's responsibility to act on carbon emissions, the Court held:

EPA overstates its case in arguing that its decision not to regulate contributes so insignificantly to petitioners’ injuries that it cannot be haled into federal court, and that there is no realistic possibility that the relief sought would mitigate global climate change and remedy petitioners’ injuries, especially since predicted increases in emissions from China, India, and other developing nations will likely offset any marginal domestic decrease EPA regulation could bring about. Agencies, like legislatures, do not generally resolve massive problems in one fell swoop, but instead whittle away over time, refining their approach as circumstances change and they develop a more nuanced understanding of how bestto proceed. That a first step might be tentative does not by itself negate federal-court jurisdiction.