New report adds concern to future of polar bears
New research suggests that ancient polar bear populations shrank as sea ice dwindled, adding weight to concerns about the predator's future as climate change melts the Arctic.
A paper published in the journal Science brings together genetic analysis and climate modelling over at least 20-thousand years.
Using old polar bear skulls from a Danish archive, the scientists measured the genetic diversity of past populations.
More diversity is thought to reflect bigger populations.
When the researchers compared those numbers to their reconstruction of ancient sea levels, they found a pattern.
More ice equalled more bears, and vice versa.
Co-author Paul Szpak from Trent University in Ontario says the findings lend weight to other studies that suggest polar bear numbers are likely to drop as sea ice continues to shrink.