US researchers have proposed a new strategy to tackle the global climate dilemma: have a universal cap across the board for carbon emission and target the biggest polluters.
After the framework is in place, countries would be tasked with getting individuals living beyond that cap to reduce their carbon footprint.
"Most of the world's emissions come disproportionately from the wealthy citizens of the world, irrespective of their nationality," said lead author Shoibal Chakravarty, a research scholar at the Princeton Environmental Institute.
"We estimate that in 2008, half of the world's emissions came from just 700 million people," he added, noting that many emissions owe to lifestyles that involve airplane flights, car use and the heating and cooling of large homes.
The plan, published in the Proceedings of the National Academy of Sciences, proposes to use national income distribution data for each individual country in order to estimate how carbon emissions are shared out among individuals.
After estimating global carbon emissions, the researchers proposed a rule to derive a universal cap on global individual emissions and determine corresponding limits.
The study did not say how the countries would implement the plan, although it noted that "a well-designed national policy would contain costs and not exacerbate inequalities."
About half of global greenhouse gas emissions come from less than a billion of the world's inhabitants, the researchers noted in explaining the logic behind their approach.
"Our proposal moves beyond per capita considerations to identify the world's high-emitting individuals, who are present in all countries," the University of Princeton research team wrote in its study.
The Kyoto Protocol, the current carbon-capping pact, charges rich countries with cutting most of the emissions while developing countries, including rapidly-developing China and India, are not required to reduce the emissions blamed for global warming.
The researchers said they hope their approach will garner the support of rich and poor countries less than six months before key UN climate change talks in Copenhagen.
As an example, they said that if global leaders set a target to maintain carbon emissions in 2030 at today's levels, no individual could emit more than 11 tons (10 tonnes) of carbon per year.
According to the projections, 1.13 billion people would be above the cap out of an estimated 8.1 billion-strong world population in 2030.
Each individual now emits a global average of five tons (4.5 tonnes) of carbon dioxide each year. Each European emits about 10 tons (nine tonnes) annually, while each American produces twice that amount, according to the study.
The researchers noted that some existing strategies based on energy use are considered unfair because they conceal the emissions of wealthy major polluters.
Allocating responsibility for carbon emissions has been the thorniest issue confronting negotiations between developed and developing countries ahead of the UN conference in December, which aims to strike a new global warming pact to replace the Kyoto Protocol that expires in 2012.