The Bush administration has for years ducked the issue of climate change and how human activities are contributing to the planet’s warming. So, it is no surprise that when the U.S. Fish and Wildlife Service recently proposed, after a court-ordered review, to list polar bears as a threatened species, the agency carefully avoided blaming the bear’s demise on climate change. If the threatened listing becomes official, this semantic distinction will likely unravel and the polar bear could well be remembered for forcing government action on greenhouse gas emissions.

Polar bear numbers are dwindling, Secretary of the Interior Dirk Kempthorne said in announcing his agency was moving to protect polar bears under the Endangered Species Act, because their habitat “may literally be melting.” Scientific observations have shown that Arctic sea ice has thinned 32 percent in some areas from the 1960s and ’70s to the 1990s, according to a Department of the Interior press release. Polar bears use the ice as a platform from which to hunt seals, their primary prey. It is also much easier for them to walk across the ice than on land and some even build dens on the sea ice. The department notes that the western Hudson Bay polar bear population in Canada has declined 22 percent and decreased cub survival and adult weight loss are problems among populations in Alaska and Canada.

The U.S. Fish and Wildlife Service cites studies that have found the amount of sea ice in 2006 to be the second lowest on record and that the pace of melting is accelerating. One study found that nearly ice-free September conditions could be reached as early as 2040.

While receding sea ice is the primary reason given for the threatened designation, the Interior Department said it would not do a scientific analysis of the causes of climate change because this is beyond the scope of the Endangered Species Act review process.

The two are hardly separable. If it is found that melting sea ice is the reason for the declines in the polar bear population, government agencies will be required to try to stop the melting. That, most likely, will require restrictions on the emissions of greenhouse gases, which trap heat in the atmosphere. Such restrictions could include limits or taxes on the emission of carbon dioxide, a byproduct of burning fossil fuels to power automobiles, factories and power plants. Improved fuel economy would also lower emissions.

The department also said it found that oil and gas exploration in Arctic regions was not harming polar bears. While the rigs and pipelines may not be harming the bears, burning the oil and gas that is extracted is contributing to global warming. Reducing oil and gas consumption would not only reduce greenhouse gas emissions, it would lead to lower prices, which would dampen the demand for further exploration.

As the federal government edges closer to protecting polar bears, it will become more difficult for it to continue to avoid taking steps to address climate change.