OSLO (Reuters) - Total greenhouse gas emissions by China and other emerging nations since 1850 will surpass those of rich nations this decade, complicating U.N. talks about who is most to blame for global warming, a study showed on Thursday.

Developing nations accounted for 48 percent of cumulative emissions from 1850 to 2010, according to the study by the PBL Netherlands Environmental Assessment Agency, research group Ecofys and the European Commission's Joint Research Center.

"Somewhere in the current decade the share of the cumulative historical emissions of developing countries will surpass that of developed countries," a statement said.

Developing nations' emissions are rising fast and the report predicted that their share of cumulative emissions would reach 51 percent by 2020.

Almost 200 governments will meet in Warsaw from November 11-22 to discuss plans for a new, global deal to fight climate change meant to be agreed in 2010 and to enter into force from 2020.

"Discussions at the U.N. climate negotiations tend to focus on which countries have contributed most to climate change," the study said.

The biggest emitters since 1850, taken as the start of widespread industrial use of fossil fuels that emit greenhouse gases when burnt, were the United States, China, the European Union and Russia, it said.

China, with 1.3 billion inhabitants, argues that its per capita emissions since 1850 are still far below those of developed nations, meaning it has less responsibility to rein in emissions than rich nations.


Separately, the PBL Netherlands Environmental Assessment Agency said that world emissions of carbon dioxide rose by just 1.1 percent in 2012 to a record 34.5 billion tones, a slowdown from annual gains averaging 2.9 percent since 2000.

"This is remarkable, as the global economy grew by 3.5 percent," it said in a statement. "This development signals a shift towards less fossil-fuel-intensive activities, more use of renewable energy and increased energy saving."

The figures were similar to a report by the International Energy Agency in June, which said that worldwide carbon dioxide emissions rose by 1.4 percent in 2012, with gains by China offsetting falls in the United States and Europe.

(Reporting By Alister Doyle; editing by Ron Askew)