Well, it also makes a lot of places near the equator uninhabitable. Forget about living in places like Phoenix, Arizona, or Miami Florida, or even Riverside, California. Entire countries in the tropics, such as India, Pakistan, Thailand, and Indonesia, may not be habitable. Where do those people go to find new homes, and what happens to the crops that are grown in those areas? Do you realize that the last time Antarctica was NOT frozen solid was about 30 million years ago. Back then humans and even apes and monkeys did not even evolve yet. Therefore humans never experienced warm global temperatures and we do not know how catastrophic it will be if Antarctica thaws. We know that some large animals such as giant penguins and large plant eating animals became extinct when the earth warmed up in the past. If animals the size of cows and horses cannot stand the warm temperatures, for example, and they were to become extinct if the earth warms up, we can be in trouble because cows are an important source of protein that would be difficult to replace.