Increase in the temperature of the earth is called global warming. To put it in a different way, the term "global warming" is also used to refer to increases in average temperature of the air and sea at Earth's surface. It has been pointed out that since the early 20th century; the global air and sea surface temperature has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.
Most of global warming was being caused by increasing concentrations of greenhouse gases produced by human activities. . In 2010 that finding was well recognized by the national science academies of all major industrialized nations. To authenticate these findings, it has been declared by the IPCC, during 2013 that the highest global warming gas is carbon dioxide that has been emitted due to burning of fossil fuels, Cement production and deforestation.
In short Human influences play a dominant role in the field of Global warming and it has been estimated that global surface temperature is likely to be increased at the range of further 0.3 to 1.7 °C. (0.5 to 3.1 °F)
The major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone (O3), which causes 3–7%. Clouds also affect the radiation balance through cloud forcing similar to greenhouse gases.
Human activity due to the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radioactive forcing from carbon dioxide, Methane, CFCs and nitrous oxide. According to work published in 2007, the concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750. These levels are much higher than at any time during the last 800,000 years.
Effects of Global warming:
It has been pointed out that global warming will bring out drastic changes in the factors such as Climate changes, seasonal changes and unexpected temperature fluctuations. And all aspects indirectly affect the health and the normal life of Homo sapiens. At present we experience unexpected very heavy rains and droughts, indicating the change in the seasons. Heat waves, wildfires, floods and droughts hit us hard in 2012 (the warmest year on record for the U.S.A. , Climate change is one of the most serious public health threats facing the nation, but many of us are unaware of the fact that how it can affect the Children, the elderly, and the communities living in poverty.
In the United States, the electric power plants emit more than two billion tons of carbon dioxide each year, or roughly 40 percent of total emissions.