To fairly divide the climate change fight between rich and poor, a new study suggests basing targets for emission cuts on the number of wealthy people, who are also the biggest greenhouse gas emitters, in a country.

Since about half the planet's climate-warming emissions come from less than a billion of its people, it makes sense to follow these rich folk when setting national targets to cut carbon dioxide emissions, the authors wrote on Monday in Proceedings of the National Academy of Sciences.

As it stands now, under the carbon-capping Kyoto Protocol, rich countries shoulder most of the burden for cutting the emissions that spur global warming, while developing countries - including China and India - are not required to curb greenhouse pollution.

Rich countries, notably the United States, have said this gives developing countries an unfair economic advantage; China, India and other developing countries argue that developed countries have historically spewed more climate-warming gases, and developing countries need time to catch up.

The study suggests setting a uniform international cap on how much carbon dioxide each person could emit in order to limit global emissions; since rich people emit more, they are the ones likely to reach or exceed this cap, whether they live in a rich country or a poor one.

For example, if world leaders agree to keep carbon emissions in 2030 at the same level they are now, no one person's emissions could exceed 11 tons of carbon each year.

By counting the emissions of all the individuals likely to exceed this level, world leaders could provide target emission cuts for each country. Currently, the world average for individual annual carbon emissions is about 5 tons; each European produces 10 tons and each American produces 20 tons.

The authors hope policymakers will look at the strong link between how rich people are and how much carbon dioxide they emit.

"You're distributing the task of doing something about emissions reduction based on the proportion of the population in the country that's actually doing the most damage," said Shoibal Chakravarty of the Princeton Environment Institute, one of the study authors.

Rich people's lives tend to give off more greenhouse gases because they drive more fossil-fueled vehicles, travel frequently by air and live in big houses that take more fuel to heat and cool.

By focusing on rich people everywhere, rather than rich countries and poor ones, the system of setting carbon-cutting targets based on the number of wealthy individuals in various countries would ease developing countries into any new climate change framework, Chakravarty said.

Is this a limousine-and-yacht tax on the rich? Not necessarily, Chakravarty said, but he did not rule it out: "We are not by any means proposing that. If some country finds a way of doing that, it's great."

(China Daily via Agencies July 8, 2009)