The BEST explanation for why climate change is often framed by images of thin polar bears surrounded by melting ice is because it is an image that immediately evokes sympathy. The polar bear has become a symbol of the impact of climate change because it is a charismatic and iconic species that people can relate to. The image of a polar bear struggling to survive on a melting ice floe is powerful and emotionally charged, and it helps to bring the issue of climate change to the forefront of public consciousness. While the other options may be true to some extent, they do not provide as strong of an explanation for why polar bears are often used in discussions about climate change.
