On this page of this site you will learn some causes of global warming. Some scientists believe that the cause is the green house effect, the process of trapping heat within the Earth's atmosphere.This happens because of the presence of large amounts of carbon dioxide. Some other theories are holes in the ozone layer caused by aerosol can sprays like spray paint or air freshener. Another is El Niño. If you want to help we need to cut down the use of fossil fuel. Scientists have measured the carbon dioxide concentration in air day after day and year after year at a laboratory on a mountain in Hawaii. The cause must be the burning of fossil fuels, especially coal.