A study by University of Michigan researchers assessed the effects of several factors on year-to-year changes in atmospheric concentrations of carbon dioxide.
Researchers looked at two natural phenomena believed to affect CO2 levels -- volcanic eruptions and the El Nino weather pattern -- and two human factors, world population and the world economy (as measured by worldwide gross domestic product.)
Of the factors, they said, growing global economies were the most likely to be linked with increases in greenhouse gases.
From 1958-2010, in every year of above-trend GDP, the researchers said there were greater increases in CO2 concentrations, a university release reported Tuesday.
To break the economic habits contributing to a rise in atmospheric CO2 levels and global warming, researcher Tapia Granados said, societies around the world would need to make enormous changes.
"If 'business as usual' conditions continue, economic contractions the size of the Great Recession or even bigger will be needed to reduce atmospheric levels of CO2," Granados, a researcher at the university's Institute for Social Research, said.
Concentrations of CO2 are estimated to have been between 200-300 parts per million during preindustrial times, are presently close to 400 ppm, and levels around 300 ppm are considered safe to keep a stable climate, the researchers said.
"Since the 1980s, scientists like James Hansen have been warning us about the effects global warming will have on the Earth," Granados said. "One solution that has promise is a carbon tax levied on any activity producing CO2 in order to create incentives to reduce emissions."
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