Quoting from this site:
Polar bears, sea ice and global warming are taboo subjects, at least in public, for some U.S. scientists attending meetings abroad, environmental groups and a top federal wildlife official said Thursday.
Environmental activists called this scientific censorship, which they said was in line with the Bush administration’s history of muzzling dissent over global climate change.
But H. Dale Hall, director of the U.S. Fish and Wildlife Service, said this policy was a long-standing one, meant to honor international protocols for meetings where the topics of discussion are negotiated in advance.
The matter came to light in e-mails from the Fish and Wildlife Service that were distributed by the Natural Resources Defense Council and the Center for Biological Diversity, both environmental groups.
Listed as a “new requirement” for foreign travelers on U.S. government business, the memo says that requests for foreign travel “involving or potentially involving climate change, sea ice, and/or polar bears” require special handling, including notice of who will be the official spokesman for the trip.
The Fish and Wildlife Service top officials need assurance that the spokesman, “the one responding to questions on these issues, particularly polar bears” understands the administration’s position on these topics.
Two accompanying memos were offered as examples of these kinds of assurance. Both included the line that the traveler “understands the administration’s position on climate change, polar bears, and sea ice and will not be speaking on or responding to these issues.”