Interesting article on Polar Bears.
Arctic studies show less sea ice promotes more photosynthesis. After sea ice had recently decreased by 9%, Stanford scientists determined productivity increased by 30%. More photosynthesis provides more food for fish. More fish feed more seals and fatter seals feed more polar bears.
To remain in the Arctic all winter ringed seals must create several breathing holes. When new thin ice first forms, they bust out several breathing holes using their heads. As winter proceeds they gnaw and claw to keep their holes open. Wherever sea ice survives for several years it becomes too thick to create breathing holes. So, across the Arctic, regions of thick ice contain the fewest seals and fewest bears. In contrast, in the Hudson Bay where new ice must form each year seals and bears are abundant!