This document discusses global warming and its causes. It begins by defining global warming as the increase in the average temperature of the earth that has been observed in recent years and is projected to continue. It then lists both natural causes and man-made causes of global warming, with the man-made causes being the release of greenhouse gases like carbon dioxide and methane from activities like burning fossil fuels, deforestation, livestock farming, and rice growing. The document also explains how greenhouse gases in the atmosphere trap heat and have increased global warming beyond the natural greenhouse effect. It concludes that human activity has increased the levels of greenhouse gases and accelerated the warming of the planet.