The phrase "dead polar bears" is an idiomatic expression that refers to a situation where there are no more viable options or possibilities available. Full definition
In 2006, Arctic wildlife biologist Charles Monnett reported sighting dead polar bears in the Beaufort Sea, concluding that «drowning - related deaths... may increase in the future if the observed trend of regression of pack ice... continues» (6 May 2006, p 10). (newscientist.com)
In 2006, Jeffrey Gleason and Charles Monnett, two government scientists working out of Alaska, published a report that described dead polar bears floating in the Arctic Ocean. (popsci.com)