Acid rain is caused by sulfur dioxide and nitrogen oxides released into the air from sources like factories. These chemicals rise high in the atmosphere and react with water and oxygen to form acidic pollutants. When acid rain falls to the ground, the nitric and sulfuric acid can damage statues, buildings, and other structures by corroding metal and causing paint and stone to deteriorate more quickly. Global warming is caused by increased levels of carbon dioxide and other greenhouse gases trapping heat in the lower atmosphere.