The "poster child" for climate change is usually a picture or video of a polar bear hanging on to what is left of arctic sea ice. There is another animal who is even more vulnerable to a warming climate than polar bears, and that is the Ringed Seal. Polar bears have had to abandon melting ice and turn to land, which is a challenge, as they have to deal with conflict from other animals and even humans. The Ringed Seal does not have this option and cannot adapt to dry land so easily, since their lives revolve around sea ice. 

Ringed seals are the smallest of the Arctic seal species. They live within the 35 degree North latitude line and the North Pole. They feed on polar and arctic cod and a variety of crustaceans. They live and rest on sea ice, even giving birth on it. When their babies are born (called pups), they form snow dens on top of the ice, which shelter their young from the extreme cold and predators. In order to make snow dens, you need snow and temperatures below freezing to keep them intact. With warming temperatures occurring earlier in the spring and freeze-ups occurring later, this collapses the snow dens and causes the arctic ice below them to break up. This also causes the seals to be separated from their young. Ringed seals are only about 23 inches long when born, so being separated from their parents exposes them to the cold, predators, and especially, diseases. These seals are more vulnerable to diseases from heavy concentration of pollutants that have accumulated in their food web.

With warmer temperatures in the Arctic, the seals are not reproducing as much and their reproductive rates have already declined. If the Ringed Seals become extinct, this will also severely impact the polar bears even more, as they are prime food for them. 

https://www.theguardian.com/environment/2017/jan/19/critical-10-species-at-risk-climate-change-endangered-world