carbon dioxide

Divvying up fair share of carbon emissions

PRINCETON (US)—Just months before world leaders are scheduled to meet to devise a new international treaty on climate change, a research team has developed a new way of dividing responsibility for carbon emissions among countries.

“Our proposal moves beyond per capita considerations to identify the world’s high-emitting individuals, who are present in all countries,” the researchers write in their report’s introduction.

The team, led by Princeton University scientists, proposes using individual emissions as the fairest way of calculating a nation’s responsibility to curb its output of carbon dioxide. The methodology does not mean that individuals would be singled out, only that these calculations would form the basis of a more equitable formula.

Many of the current strategies that employ averages of energy use in a country are widely regarded as unfair, the authors say, because such efforts mask the emissions of wealthy, high polluters.

“Most of the world’s emissions come disproportionately from the wealthy citizens of the world, irrespective of their nationality,” says physicist Shoibal Chakravarty, a research associate at the Princeton Environmental Institute, noting that many emissions come from lifestyles that involve airplane flights, car use and the heating and cooling of large homes. “We estimate that in 2008, half of the world’s emissions came from just 700 million people.”

The approach is so fair, according to the team, that they are hoping it will win the support of both developed and developing nations, whose leaders have been at odds for years over perceived inequalities in previous proposals.

The proposal “provides a significant starting point for breaking through the current impasse over the respective mitigation responsibilities of developed and developing countries,” says Robyn Eckersley, a professor at the University of Melbourne in Australia who specializes in environmental politics and political theory.

The researchers believe their new framework is useful in that it establishes a uniform “cap” on emissions that individuals should not exceed. If, for example, world governments agreed to curtail emissions so that carbon levels in 2030 are approximately at present levels, then, according to the researchers’ calculations, the necessary reductions in global emissions could be achieved if no individual’s emissions could exceed about 11 tons of carbon dioxide a year. By counting the emissions of all the individuals who are projected to exceed that level, the world leaders could provide target emissions reductions for every country. For this specific example, there will be about 1 billion such “high emitters” in 2030 out of 8.1 billion people.

At present, the world average for tons of carbon dioxide emitted a year per individual is about five. Each European produces about 10 tons a year, with each American producing twice that amount.

“These numbers strengthen our conviction that industrialized countries will have to take the lead in reducing their emissions, but that the fight to prevent dangerous climate change can only be won if all countries act together,” says Ottmar Edenhofer, the chair of Economics of Climate Change at the Technical University Berlin and cochair of Working Group III of the Intergovernmental Panel on Climate Change.

The new research paper shows it is possible to reduce poverty and cut carbon emission at the same time. The authors calculate that addressing extreme poverty by allowing almost 3 billion people to satisfy their basic energy needs with fossil fuels does not interfere with the goal of fossil fuel emissions reduction. The cap would need to be somewhat lower, and high emitters would need to reduce their energy consumption by a slightly larger percentage to make up the difference.

World leaders are expected to meet in Copenhagen in December 2009 for a conference to negotiate a treaty on global emission reductions to address climate change. The 1992 United Nations Framework Convention on Climate Change called upon the developed nations to reduce carbon emissions and provided the impetus for the binding 1997 Kyoto Protocol, but established no time frame for developing countries to follow. Developing countries now contribute more than half of global emissions, a share that is growing at a fast pace, Chakravarty says.

“U.N. rules and customs make it difficult for the international community to examine what is going on inside countries. That’s probably why our simple proposal based on individual emissions has not emerged from the diplomats,” says Robert Socolow, a professor of mechanical and aerospace engineering at Princeton. “Over the next several decades, global environmental rulemaking will need new wisdom to accommodate developing countries whose per capita data belie the presence of both large populations of the very poor and upper and middle classes that are major consumers of resources. Our proposal is a start down this road.”

Researchers from Harvard University and the Energy Research Centre of the Netherlands contributed to the report. The proposal is outlined in a paper published online in Proceedings of the National Academy of Sciences.

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