What are we doing to the planet?

I was having a discussion with someone over the different kinds of cars that are now available or will be in the future, then the real problem came to me, and boils down to this.

I say anytime you wrap a 200 LB person with 2000 plus pounds of metal the environment is going to pay a steep price. As creatures we were each meant to release a few hundred watts into the environment per hour at most. Now, using cars we are releasing 10 of thousands of watts per hour, any way you slice it up (regardless of the power source) the planet can't tolerate absorbing that kind of heat from billions of people. We are doomed folks, have a good ride while it lasts.