A large fraction of emissions of carbon dioxide (CO2)Ñthe greenhouse gas produced by human activities in the greatest quantitiesÑis long lived in the atmosphere, so decisions made today to continue adding CO2 into the atmosphere may lock future generations into a range of human health and environmental impacts, some of which could become very severe, according to a committee of the National Research Council (NRC). In a report that looks at the short- and long-term effects of the stabilization of EarthÕs temperature, the NRC committee quantifies, as much as possible, the outcomes of different stabilization targets for the planet, with a focus on the United States.