Global warming refers to the rising average temperature of Earth´s atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about 0.8 °C (1.4 °F) with about two thirds of the increase occurring over just the last three decades. Warming of the climate system is unequivocal, and scientists are more than 90% certain most of it is caused by increasing concentrations of green houses produced by human activities such as deforestation and burning fossil fuel . These findings are recognized by the national science academies of all the major industrialized countries.
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