The science and commentary website Vox has an interesting article related to polar bear population. It has long been a contention that global warming is affecting polar bear populations which could lead to their extinction. However, the article states polar bear population declines depend on where you seek them. The article states not only are some polar bear populations are going down but others are also holding steady. One other point brought up that no one takes into account is the potential for polar bears to cross-breed with other bear species such as Grizzlies in which there is evidence this is happening too.
In the below video done by the Global Warming Policy Foundation, University of Victoria, Canada adjunct professor and polar bear expert Dr. Susan Crockford discusses her research on the subject.