The study, published in the Proceedings of the National Academy of Sciences (PNAS), was conducted by researchers from the National Center for Atmospheric Research (NCAR), the International Institute for Applied Systems Analysis (IIASA), and the National Oceanographic and Atmospheric Administration. It was funded by a European Young Investigator's Award*, the Hewlett Foundation, and the US National Science Foundation.

By mid-century it is estimated that global population could rise by more than three billion people, with most of that increase occurring in urban areas. The study showed that a slowing of that population growth could contribute to significantly reducing greenhouse gas emissions. By 2050, the researchers found that if population followed one of the slower growth paths foreseen as plausible by demographers at the United Nations, it could provide 16 to 29 percent of the emission reductions thought necessary to keep global temperatures from causing serious impacts. The effect of slower population growth on greenhouse gas emissions would be even larger by the end of the century.

"If global population growth slows down, it is not going to solve the climate problem, but it can make a contribution, especially in the long term," says the study's lead author and NCAR scientist Brian O'Neill.

Study co-author and IIASA scientist Shonali Pachauri says that slower population growth will have different influences, depending on where it occurs. "A slowing of population growth in developing countries today will have a large impact on future global population size. However, slower population growth in developed countries will matter to emissions too because of higher per capita energy use," says Dr Pachauri.

Scientists have long known that changes in population will have some effect on greenhouse gas emissions, but there has been debate on how large that effect might be.

(ScienceDaily)

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