Global carbon dioxide emissions may be dropping slightly this year, spurred by a dramatic plunge in Chinese pollution, research suggests.
The unexpected dip could either be a temporary blip or true hope that the world is about to turn the corner on carbon pollution as climate talks continue in Paris, said the authors of a study published in the journal Nature Climate Change.
"That shouldn't tell us we don't need to do anything, but that shows there is action," Janos Pasztor, the United Nations assistant secretary general for climate change, told The Associated Press at the Paris climate talks. "Things are going in the right direction. All we need is a strong agreement."
Using preliminary data to October 2015, the international team of emission trackers project that worldwide emissions this year will end 200 million metric tonnes of carbon dioxide less than the 35.9 billion metric tonnes they calculated for 2014 - a 0.6% decrease.
But there's a margin of error - so the difference from last year to this could be as big a drop of 1.6% or actually a 0.5% increase, the study said.
The projected global emissions for 2015 calculate to the world spewing on average 68 million kilograms of carbon dioxide each minute.
Study authors said this would be the first time global carbon dioxide emissions have dropped, even if only slightly, while the world economy grows. Global emissions fell during the last big recession.
The team's emissions figures for 2014 - not projections but hard data - show a 0.6% increase from 2013, about 200 million metric tonnes.
That is much lower than previous annual rates. From 2000 to 2009, world heat-trapping gas emissions grew about 3.3% a year and in recent years it was in the 1 to 2.5% range, said study co-author Corinne Le Quere of the University of East Anglia. But it could also be a blip with emissions going right back up, she said.
"We have a mountain (of emissions) in front of us," Ms Le Quere said. "Maybe the mountain is a bit less and steep than we thought. But it's still a mountain."
US environmental protection administrator Gina McCarthy said: "I will take the blip any day; it's much better than saying it's increasing. But I think it may just represent a strategy that will be more long term."
Greenpeace's international climate politics chief, Martin Kaiser, said this is not enough of a reason to celebrate or be complacent, as emissions have to come down fast in order to save the planet.
Stanford University's Ken Caldeira expressed even deeper caution. He offered to bet the authors 10,000 US dollars that emissions have not peaked yet, a bet the authors were not willing to take.
Ms LeQuere said she also thinks world emissions, including China's, will go back up and 2014 will not end up being the peak year. She said emissions could go up or down a bit from now on.
The whole apparent drop is driven by China, said study co-author Glen Peters of the Centre for International Climate and Environmental Research in Oslo. Their study shows a nearly 4% drop in emissions for the first eight months of the year when compared to the same time last year. China's plans do not have the country hitting carbon dioxide peak emissions until 2030, which is 15 years from now.
One factor may be issues concerning emissions reporting accuracy with China - and the monitoring and verification of emissions is a major hurdle in climate talks. Mr Peters is confident that his figures based on industrial activity are good. But when asked if he trusts Chinese official emissions reporting figures, he paused and said, "you certainly have your doubts".
China has dramatically increased its renewable energy and is capping its coal burning, much of it driven by the effort to clean up traditional air pollution that is choking cities like Beijing, said study co-author Dabo Guan of the University of East Anglia. Those efforts are aimed at coal because "coal is the criminal for that and they are reducing lots of coal consumption in the urban areas where most of the industry is based," he said.
US emissions in 2015 dropped by about 1.5%. Ms Le Quere only had 2015 estimates for China and the US. But in 2014, Europe's emissions went down 6% or by 200 million metric tonnes - which was the same amount by which India's emissions rose, Mr Peters said.