Nations hoping to curb global warming face a quandary: Economic growth means more planet-warming carbon dioxide emissions. On the flip side, economic decline means a drop in greenhouse gas emissions as consumers tighten their belts, factories slow down and less money is spent. A new analysis of data from 1960 to 2008 indicates during economic decline carbon dioxide emissions decline at about half the rate at which they grow when an economy is booming. "In a sense, economic decline only undoes a little more than half of the carbon dioxide emissions that economic growth adds,” said Richard York, a professor of sociology and environmental studies at the University of Oregon who conducted this study. This result indicates that a country's history — not just its current economic state — influences the amount of carbon dioxide it is pumping out.