However, water vapor is far less efficient at trapping heat within Earth's atmosphere than CO2, the leading fossil-fuel-based greenhouse gas. Despite its prevalence, water vapor tends to concentrate locally and then get cycled through the meteorological system quickly (in the form of clouds and then rain). Meanwhile, CO2 lingers in the upper atmosphere for long periods of time and forms a dense barrier to the escape of heat. While water vapor can cause short-term day-to-day warming locally, CO2 is already raising the Earth's temperature both globally and permanently.
Industrial designer Robert Q. Riley argues, "Natural evaporation from lakes and rivers produces about 1,000 times more water vapor than would come from a transportation system that was totally powered by fuel cells." CONTACT: Intergovernmental Panel on Climate Change, www.ipcc.ch; Weather Prediction Website, www.theweatherprediction.com.
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