New method may help allocate carbon emissions responsibility among nations

PETTEN, Netherlands – Just months before world leaders are scheduled to meet to devise a new international treaty on climate change, a research team led by Princeton University scientists, and including ECN researcher Heleen de Coninck, has developed a new way of dividing responsibility for carbon emissions among countries.

The approach is so fair, according to its creators, 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 method is outlined in a paper, titled "Sharing Global CO2 Emissions Among 1 Billion High Emitters," published online in this week's Proceedings of the National Academy of Sciences. According to the authors, the approach uses a new fairness principle based on the "common but differentiated responsibilities" of individuals, rather than nations.

The proposal would use individual emissions as the best, fairest way of calculating a nation's responsibility to curb its output of carbon dioxide, the authors said. The methodology does not mean that individuals would be singled out, only that these calculations would form the basis of a more equitable formula. Some present 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," Chakravarty said, 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."

In the new scheme, emission reduction targets for each country are calculated in a multi-step fashion. The researchers used a strong correlation between income and emissions to estimate the emissions of individuals in every country. Next, they combined these factors to see how individual emissions are distributed globally. Looking forward to 2030, the researchers estimated first individual emissions and then a global emission total at that future time based on projections of income, population and energy use. They imagined the world's leaders deciding now that the projected global emission total for 2030 is dangerously high, choosing a lower global target and seeking a process by which the work of achieving this new global target could be divided among the world's nations.

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.

The new research paper shows that 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.

The authors believe the paper will be of relevance to climate negotiators, who will meet in Copenhagen in December 2009 to agree on a new climate treaty. Currently, those negotiations are in a stalemate between developed and developing nations.

“With this proposal”, Heleen de Coninck said, “it is more likely that major developing countries would take on a formal commitment . The main reason these nations state for their resistance of emission caps is that their first priority is to lift those hundreds of millions of poor people out of poverty, not to reduce emissions. But in this new approach, their targets would be based only on those people that are not living in poverty - it is the more affluent people who appear higher on the income distributions and, hence, have higher emission. These are the ones the country cap is based on. In addition, it provides the rich countries, which have many more high emitters, with more stringent targets than poorer countries.”

Authors on the paper are: Shoibal Chakravarty (Princeton University), Robert Socolow (Princeton University), Heleen de Coninck (Energy research Centre of the Netherlands), Stephen Pacala (Princeton University), Ananth Chikkatur (Harvard University) and Massimo Tavoni (FEEM (Italy)/Princeton University).

For further information, please contact:
Press Officer ECN Florentine de Maar
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