The rate of carbon dioxide (CO2) emissions is accelerating all over the world, according to a paper in the journal Proceedings of the National Academy of Sciences. In fact, CO2 emissions are growing faster than the most extreme forecasts by the Intergovernmental Panel on Climate Change (IPCC).

From 1990-1999, the amount of carbon dioxide released into the atmosphere increased by 1.1 percent; from 2000-2004, the emissions growth rate tripled to three percent each year.

Most of the CO2 in the atmosphere is released when coal, oil and natural gas is burnt for energy. But other contributors exist—cement-production, for example, which involves burning calcium carbonate to expel carbon, accounts for about three percent of the total emissions.

Chris Field, director of the Carnegie Institution’s department of global ecology at Stanford in CA, and colleagues, including Gregg Marland, a researcher in the environmental sciences division at the Oak Ridge National Laboratory in Oak Ridge, TN developed an equation that helps explain what is causing the acceleration in emissions.

The researchers looked at four factors: population, individual wealth (gross domestic product—GDP—per person), energy efficiency of the economy (energy per unit of GDP) and how much C02 is produced per unit of energy. Coal, for example, produces more carbon dioxide per unit of energy than any other major energy source, says Marland.

“The conclusion is that CO2 is going up faster than anyone expected,” Marland says. The IPCC predicted a slower growth rate, but the assumption was based on the idea that we would move towards energy sources that are more efficient—sources that produce less CO2 per unit of energy, Marland says. The other assumption was that our economies would become more efficient, requiring less energy for the same amount of product.

Historical data backed up these assumptions: “The trend had been downward for the last twenty years or more, and they assumed those [variables] would continue to decline,” Marland explains.

Why have these factors—the amount of CO2 emitted per unit of energy and the amount of energy it takes to run the economy—started increasing in recent years? “They’ve turned up for a couple of reasons, I think, and part of it is that there is only so much hydropower you can establish, the limits on nuclear power...,” says Marland. The other key factor is that America and other developed nations are moving production to less developed nations. Marland says: “We’re moving our CO2 emissions offshore. But by moving things to countries like China, we move the energy source to more coal, for example.”

The U.S. may be decreasing domestic energy efficiency, but if it’s moving production to countries like India and China that use less efficient energy sources, global emissions will accelerate.

The data show that no region has decreased the rate of carbon emissions in the last four years.  In developed countries, like the United States, increase in population and wealth contributed to the increased output of CO2. This type of growth is important to the calculation, Marland says, “but it’s not the whole story.”

-Flora Lichtman

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