Energy giants want carbon scheme

In a letter on Monday, the companies appealed to the UN's top climate official, Christiana Figueres, saying the best way to encourage greener investments in the industry was to make polluting more expensive.

A global pricing scheme for carbon emissions would make that possible, they said, and could resemble a European Union emissions trading system. Their suggestions were met coolly by the two largest American oil companies, ExxonMobil and Chevron, who said they would not be party to any European push on global warming.

The letter's authors, which included the heads of France's Total, Norway's Statoil, Italy's Eni, Britain's BP and BG Group and Anglo-Dutch Royal Dutch Shell, highlighted the benefits of burning natural gas, which is both cleaner than coal and already a major source of income for the firms.

"Our request to policy makers as they prepare for the UN talks is not to ask for special treatment for any resource, including natural gas, or any single route to a lower-carbon future," the letter read. "It is rather to ensure that the outcome of these talks leads to widespread carbon pricing in all countries."

Government officials are meeting in the German city of Bonn this week to try and forge a plan for combating climate change that would be finalized in Paris at the end of the year, but prospects of a deal are slim as some climate officials have admitted that national plans to curb emissions will not be radical enough.

More would need to be done, say many scientists and climate advocates, to prevent temperatures from rising two degrees Celsius above pre-industrial levels, a target that has long been identified as a ceiling beyond which extreme changes in weather would only worsen.