Tipping Points to Global Warming

I am watching a video that says that Global warming is near a tipping point. It is going to get so hot, we could have temperature rises of 7-centigrade. He (Prof. Keohane of NYU) is saying that everything will collapse in the environment the same way that the financial derivative bubble collapsed.

This is a total fairy tale I think. The world needs to cut emission of greenhouse gases by 50-percent. You are also supposed to let developing countries grow. That means cutting USA emissions by 80-percent. That is insane, that is impossible. These people are nuts. Of course we could switch to nuclear power and artificial, nuclear manufacture of gas fuels. But the greenie, environmental mainstream wants renewal so-called sources. Impossible, beserk.