By Richard Black
Environment correspondent, BBC News website
Listing the polar bear might lessen industry's impact on the Arctic
A judge has told the US government to decide within weeks whether to list polar bears as an endangered species.
The decision was hailed by conservation groups which have been hounding the government on the issue for years.
The federal judge rejected the Bush administration's pleas for a further delay, and ordered it to make and implement its decision by 15 May.
A listing could restrict oil and gas exploration in the US Arctic, and lead to curbs on greenhouse gas emissions.
"Today's decision is a huge victory for the polar bear," said Kassie Siegel, climate program director with the Center for Biological Diversity, one of the conservation groups behind the legal challenge.
"By 15 May, the polar bear should receive the protections it deserves under the Endangered Species Act, which is the first step toward saving the polar bear and the entire Arctic ecosystem from global warming."
The conservation groups argue that with polar bear numbers declining, there is an urgent need to protect its remaining habitat.
But the government had stalled on making a decision since the original petition went forward in 2005.
At the court, Judge Claudia Wilken ruled that the slow progress put the government in breach of its obligations.
"Defendants have been in violation of the law requiring them to publish the listing determination for nearly 120 days," she concluded.
Polar bears' ice habitat is being compromised by climate change
Judge Wilken also denied the government's request for a further delay, and ordered it to forgo the traditional 30-day waiting period between making a decision and implementing it.
The US Fish and Wildlife Service must now decide whether to list the polar bear as endangered, or to put it in a lesser category of risk such as threatened, or to keep it off the list entirely - an option which would immediately lead to further legal action from the conservation coalition.
If it is listed, campaigners will argue that anything that might impinge on the creature's habitat, such as recently announced plans for oil and gas exploration off the Alaskan coast, must either be cancelled or put under much more rigorous scrutiny.
They will also argue that the only way to prevent the Arctic becoming entirely ice-free in summers in the coming decades is to make drastic cuts in greenhouse gas emissions.
Two years ago, scientists compiling the internationally recognised Red List of Threatened Species decided to include polar bears, giving them a listing of Vulnerable to Extinction.
Warming Arctic seas and a marked decline in sea ice during the summer months made it likely, they concluded, that numbers would fall by one third within three generations (45 years).