Each person on the planet produced 1.3 tons of carbon last year—an all-time high--despite a global recession that slowed the growth of fossil fuel emissions for the first time this decade, according to a report published this week in the journal Nature Geoscience. Emissions grew 2 percent last year, to total 8.7 billion tons of carbon dioxide.
The report was compiled by scientists affiliated with the Global Carbon Project , a group that provides policymakers with an annual accounting of global carbon dioxide levels. Though the bad economy had an environmental upside by slowing the growth of heat-trapping gases in the atmosphere, the authors warn that emissions will rebound unless leaders act.
"Reduction of CO₂ emissions is a very urgent task," said study coauthor Taro Takahashi , a geochemist at Columbia University’s Lamont-Doherty Earth Observatory. “Global population is increasing, and so is the standard of living for the developing world. We need to conserve energy by building more efficient cars and power plants. We should also develop technology to capture carbon dioxide from the air and store it away permanently."
Atmospheric carbon dioxide levels now average 385 parts per million, a 38 percent increase from preindustrial levels, according to the report. While emissions grew at an average rate of 1 percent a year in the 1990s, the rate jumped to 3.6 percent a year this decade, as the developing world produced more manufactured goods, in part to feed consumer demand in the developed world.
In China, 50 percent of the growth in emissions from 2002 to 2005 went toward the production of exports, the report found. In the United States, domestic emissions grew 6 percent, while “consumption-based emissions,” which included manufactured goods from China, increased 17 percent. “This shows that developed nations are partly responsible for the growth of emissions in developing nations,” said Takahashi. “This may help bring about more equitable international agreements to lower CO₂ emissions.”
Globally, emissions continue to track the worst-case scenario laid out by the Intergovernmental Panel on Climate Change , an international panel of scientists charged with evaluating the risk of climate change.
Less than half of the carbon dioxide that humans put in the air stays there; oceans, plants and trees absorb the rest. Carbon uptake on land appears to be holding steady; the land may even be taking up more carbon than it is giving off, because carbon dioxide can have a fertilizing effect on plants, boosting growth, according to the report. But there is growing evidence that the oceans are failing to keep pace with rising human emissions.
"The fraction of emissions remaining in the atmosphere has increased over the past 50 years,” said coauthor Pep Canadell, head of the Global Carbon Project and a climate scientist at Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation. "This is of concern as it indicates the vulnerability of the sinks to increasing emissions and climate change, making natural sinks less efficient ‘cleaners’ of human carbon pollution."