After Paris: can polar bears survive climate change?
In Paris, governments agreed to limit global temperature rises to below 2˚C; but will this be enough to save the species that has come to best represent the threat to our planet from global warming, the polar bear?
Because they require sea ice in order to hunt seals – the prey that make up the vast majority of their diet – polar bears have been dubbed the “poster boys” of climate change.
Without year-round sea ice in the Arctic, say scientists, there will be no polar bears.
So let us assume for a moment that the Paris Agreement does indeed, as governments promised, limit the rise in global temperatures to "well below 2˚C" – is there a future in that world for Arctic sea ice and therefore polar bears?
Well, probably yes, says Dr Steven Amstrup, the chief scientist of Polar Bears International and one of the world’s leading polar bear scientists.
“In a paper I published in Nature in 2010, we showed that holding global temperatures to approximately 1 1/4˚C above pre-industrial [levels] would assure survival of polar bears in much of the High Arctic of northern Canada and Greenland,” Amstrup told BBC Wildlife.
A rise of 1 ½˚C would also not be catastrophic, and a rise of 2˚C would allow bears to survive in some areas.
“That is the good news about the Paris Accords, and I am more optimistic now, than I have been for a long time, about our willingness to deal with global warming,” Amstrup added.
But he warned that there was much wrong with outcome of the Paris talks. “What are the specific greenhouse gas targets associated with these proposed temperature limits?” Amstrup asked.
“No fees for emissions were established, and there doesn’t appear to be any specific information about how the goals will be achieved.”
Any rise in global temperatures approaching 3˚C gives a 50 per cent chance of the polar bear going extinct in most of its current range, he said.
A paper he co-authored earlier this year demonstrated that polar bears cannot replace hunting seals on sea ice with predating terrestrial species such as musk-ox, reindeer or seabirds, as has been suggested by some scientists.
“No study has documented a meaningful contribution of terrestrial foods to individual bear nutrition,” the paper in Frontiers in Ecology and the Environment states.
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