Global Warming is shorthand for the climate changes that may result from excessive heat being trapped in the Earth's atmosphere by so called green house gases. Global warming as defined in out test is "the gradual rise in world temperature, a suspected consequence of greenhouse gases trapping heat emitted from Earth that would otherwise escape in outer space" (380).
This climate change can be attributed to several different possibilities both natural and forced through human activity. "The general state of the Earth's climate is controlled by the balance of energy the earth releases back to space"(Colls). One natural action, which can cause change, is the Earth's shift in orbit rotating around the sun, this changes the amount of energy we receive from the sun. Other natural causes are within the oceans, atmosphere, ice sheets and volcanic eruptions to name a few. Such natural causes have created a series of ice ages on Earth. .
Over more recent years humans have caused many changes to the Earth which is a major cause for global warming. The burning of fossil fuels, deforestation, landfills, methane from rice cultivation and cattle raising are all examples of man-made greenhouse effect and global warming. The Greenhouse effect more specifically is the effect of "Warming of the Earth's atmosphere caused by the presence of certain heat-trapping "greenhouse" gases in the atmosphere"(Colls).
Over the past few decades scientist have been reviewing the changing weather patters due to global warming. The amount of rainfall, temperature and humidity are all showing significant change. Over the past two decades the Earth's temperature has substantially increased as is expected to increase more. Mountain glaciers have retarded dramatically while sea levels are rising. This could cause flooding and loss of much land in years to come. In other areas there are extreme cases of drought.