How are animals hurt by global warming?

Animals have evolved to live in certain areas with certain weather patterns. Global warming shifts the weather patterns which then changes what resources are available to the animals. For instance, there are animals that have evolved to live in the estuaries, where rivers empty into the oceans. The salt level in the estuary is mid-range between the fresh water of the river and the salt water of the ocean. Global warming can shift how much fresh water is coming down the river, which then changes the salt concentration in the estuary. If the salt concentration changes too much, the animals living in the estuary can go extinct.