Reuters: The U.S. government must decide first if polar bears are threatened by climate change before it opens part of their icy habitat to oil drilling, the head of a congressional environment panel said on Thursday. The decision whether to list the big Arctic bear as threatened under the Endangered Species Act was supposed to happen last week but was postponed for up to 30 days. That means it could come after the government offers 29.4 million acres in the Chukchi Sea off the Alaskan …