We've known for some time that global warming spells big big trouble for the world's polar bear populations. That's why NRDC, the Center for Biological Diversity, and Greepeace petitioned to have the polar bear protected under the Endangered Species Act. But just how grim the picture is was made stark by the U.S. Geological Survey of Friday.
In a series of studies, the agency is now predicting that two-thirds of the world's polar bears (constituting 11 of the 19 recognized subpopulations) will be extinct by midcentury, with another 3 subpopulations disappearing shortly thereafter.
For a sense of what I'm talking about, check out the map below. The study this map is taken from predicts that polar bears within the pink (Divergent ice) and green (Seasonal Ice) "ecoregions" will be extinct by 2050 and that the bears in the light blue areas (Convergent ice) will be gone by 2075, leaving only a small grouping of bears in the Canadian arctic (the yellow area) by century's end.
But all of this is not inevitable. These studies also point out that "timing and relative magnitude of projected sea ice extent are remarkably similar to the inverse of their imposed CO2 loadings." In other words, as we reduce C02 emissions, ice loss will eventually decrease correspondingly. That's why we need to act now and cut global warming pollution 25% by 2020 and 80% by 2050.