The use of nuclear power from 1971 to 2009 prevented more than 1.8 million premature deaths related to air pollution and 64 billion tons of greenhouse gas emissions, a new study says. Using historical production data and estimates of mortality per unit of electricity generated, scientists from NASA’s Goddard Institute for Space Studies and Columbia University calculated that replacing nuclear energy sources with fossil fuel-burning sources during that period would have caused about 1.84 million premature deaths. By midcentury, they project, nuclear power could prevent an additional 420,000 to 7 million deaths, depending on which fossil fuels it replaces, and 80 to 240 billion tons of greenhouse gas emissions. “By contrast, we assess that large-scale expansion of unconstrained natural gas use would not mitigate the climate problem and would cause far more deaths than the expansion of nuclear power,” said Pushker A. Kharecha, who, along with NASA’s James Hansen, co-authored the study published in the journal Environmental Science & Technology. The study calculated that nuclear power plant accidents caused about 4,900 deaths during the same period.