GLOBAL WARMING

Global warming is the term used to describe a gradual increase in the average temperature of the Earth's atmosphere and its oceans, a change that is believed to be permanently changing the Earth’s climate forever. While many view the effects of global warming to be more substantial and more rapidly occurring than others do, the scientific consensus on climatic changes related to global warming is that the average temperature of the Earth has risen between 0.4 and 0.8 °C over the past 100 years.Scientists worry that human societies and natural ecosystems might not adapt to rapid climate changes. An ecosystem consists of the living organisms and physical environment in a particular area. Global warming could cause much harm, so countries throughout the world drafted an agreement called the Kyoto Protocol to help limit it. Observations show an increase of intense tropical cyclone activity (hurricanes and typhoons) in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There is some evidence for increased intensity of tropical cyclone activity in some other regions. The report has found no clear trend in the annual number of tropical cyclones. As expected with warming and the resulting observed increases in water vapor, the frequency of heavy precipitation events has increased over most land areas. Between 1900 and 2005, long-term trends show significantly increased precipitation in eastern parts of North and South America, northern Europe and northern and central Asia. Between 1900 and 2005, drying has been observed in the Sahel (the boundary zone in Africa between the Sahara desert and the more fertile region to the south), the Mediterranean, southern Africa, and parts of southern Asia. More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics. Droughts have been linked to changes in sea surface temperatures and wind patterns and decreased snowpack and snow cover.