Why is the world so hot these days?

We put a lot of pressure on the world, like cutting down tree's, the gas in car's, garbage, and other stuff that we do to our environment. That also result's in the weather and stuff that we need to survive. But many people don't really realize that. If we can't keep the world safe, then want's going to happen in the following generations? It'll get worse by the time goes on, if we keep destroying the world.