The leading cause of global warming is burning fossil fuels for energy. All over the world power plants are burning fossil fuels such as coal, natural gas, and petroleum. Here is a picture telling how many pollutants are released into the atmosphere by the burning of fossil fuels.
In America in 2002 almost 70% of energy created comes from burning fossil fuels.
With the burning of fossil fuels and the release of carbon dioxide, earths average temperature is increasing. Fossil fuels aren't only burnt for electricity. Natural gas is burnt for ovens and heat, and cars burn petroleum to run. With an increasing global population this could be a major problem. The more people there are the more the more energy is required, and the more burning of fossil fuels is required.