Global warming is caused by carbon dioxide and other greenhouse gases trapping heat in the atmosphere. This is warming the earth and melting ice caps and glaciers, which causes sea levels to rise and threatens coastal areas. As temperatures increase, climate changes are altering ecosystems and threatening plants and animals through shifting habitats and increased droughts and fires. The rapid warming seen in recent decades is unprecedented and is primarily due to human emissions of carbon dioxide from fossil fuel usage. Unabated, global warming will continue to have damaging environmental and economic consequences.