While it may be impossible to predict when those very bad years will come, they write, the Arctic nations with polar bear populations – the US, Canada, Russia, Norway and Greenland – need to begin planning now for when they do.
(As an aside, it is worth noting here that some recent articles and broadcasts have lent credence to the recurring canard that polar bear populations are doing just fine, or that, even if they aren't, there are "four to five times" more polar bears now than there were 40 years ago. Despite being treated as fact, this myth has its basis in the willful misrepresentation of comments made at a 1965 scientific meeting, as this post expertly details.)
As lead author Andrew Derocher of the University of Alberta has previously observed, one very bad ice year could leave hundreds of polar bears stranded on land for weeks on end, unable to feed. In Hudson Bay, for example, the ice melts completely in the summer, forcing bears to hunker down in cool dens ashore until it reforms in the fall.