Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation. Increasing global temperature is expected to cause sea level to rise, an increase in the intensity of extreme weather events, and significant changes to the amount and pattern of precipitation. Other expected effects of global warming include changes in agricultural yields, modifications of trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors.
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