According to a report by information provider Thomson Reuters and BSD Consulting, a global sustainability consultancy, emissions by 32 energy companies firms, including the final burning of coal, gas and oil, accounted for 11.7 billion tonnes of greenhouse gases, equivalent to 31 percent of the global total in 2013.
Russia's Gazprom is the biggest emitter, Coal India second, ahead of miner and energy trader Glencore, PetroChina, Russian oil firm Rosneft, Royal Dutch Shell and Exxon Mobi.
"This is not a naming and shaming exercise," the authors wrote in the report. "These are all companies that provide vital energy services to the global economy. They are also the companies that can provide the leadership for the next generation of low-carbon energy and or respond to the leadership from competitors, regulators or consumers."