Human beings have a tendency to mess up their surroundings.
One of the primary ways we do this is by burning fossil fuels. Fossil fuels are natural materials such as oil, gas, and coal which we use for most of our energy. When burned, these materials produce oxides that eventually fall as acid rain, causing heavy metal poisoning and destroying eco-systems. Ironically, at the same time this good ozone layer is weakening, the greenhouse gases in our atmosphere that insulate the earth are being strengthened by these chemicals, which, in turn, causes global warming.