Only 1.2 trillion metric tons of carbon dioxide can be emitted in the future if nations are to avoid causing the global mean surface temperature to rise more than 2 degrees C beyond the pre-industrial average, according to researchers with the Global Carbon Project.
Historical (black dots) and projected (red dots) global CO2 emissions in trillions of metric tons. (Image credit: Friedlingstein et al., Nature Geoscience 2014)
Combined historical and future carbon dioxide emissions must remain below 3.2 trillion metric tons to have a 66-percent chance of keeping that temperature increase below 2 degrees C — the internationally accepted benchmark for restraining global warming. But two-thirds of this allotment has already been emitted, and at the current pace of emissions, the global population will burn through the rest within the next 30 years, the researchers conclude.
CO2 emissions rose 2.3 percent in 2013 and are on track to increase by another 2.5 percent in 2014, according to the report, which was released ahead of tomorrow’s UN climate summit in New York. China and the U.S. were the leading emitters in 2013 and were responsible for 28 percent and 14 percent, respectively, of global CO2 emissions.