The volume of carbon dioxide belched into the atmosphere from human activity this year is on track to decline slightly from last year's emissions, according to a new analysis published in the journal Nature Climate Change on Monday. The anticipated decrease in CO2 emissions comes even as the world economy is growing, suggesting a turning point in clean energy development—and a long-hoped-for "decoupling" of economic growth and increased carbon emissions.
A flattening of emissions in 2014 and this year's expected decrease contrast with the rapid growth of emissions over the past decade. It is, however, far from the zero or near zero emissions required to halt global warming. Some say the trend in declining emissions is only temporary, but others counter that the finding offers a rare glimmer of hope in the fight against climate change.
"I think we could be seeing a new trajectory of CO2 emissions," said Stanford University's Robert Jackson, the paper's lead author. "I hope it's the start of a long and challenging downward trend."
Decreased coal use in China—whose carbon dioxide emissions account for nearly one-third of global emissions—was largely responsible for the decline in global emissions, the researchers concluded. After a decade of rapid growth, China's emissions rate slowed to 1.2 percent in 2014 and is expected to drop by approximately 3.9 percent in 2015, according to the report. More than half of new energy needs in China were met in 2014 from non-fossil fuel sources, such as hydro, nuclear, wind and solar power.
China committed to reaching a peak in its emissions by 2030 in a voluntary climate pledge made prior to the United Nations' ongoing climate negotiations. The talks in Paris have drawn world leaders from around the globe, seeking a global climate agreement reining in greenhouse gas emissions.
Jackson, a professor of earth system science and chair of the Global Carbon Project, the non-profit organization that produced the study, said he thinks China's emissions will rise slightly in coming years but could peak well before 2030. The current decline in emissions comes as the world's economy has consistently grown more than 3 percent per year since 2012.
"The only time in the past when we have had a drop in emissions is when we had global recessions, like the collapse of the Soviet Union, so that is really quite remarkable and it gives us hope," said David Reay, a professor of carbon management at the University of Edinburgh in Scotland. "Maybe this is it, maybe this is the turning point."
Others are less optimistic.
"There are encouraging signs of downward trends in carbon dioxide emissions in many parts of the world, but it is too soon for self-congratulations," said Robert Socolow, a carbon mitigation expert at Princeton University. "There has been a tendency to say, 'well, China has gone over some kind of hump,' which it has, it's not deploying coal plants [domestically] as fast as it used to. But they are both financing and exporting their coal technology all over Asia."
For global emissions to continue their decline, emissions in China, the U.S., and Europe would have to drop faster than the increases in India, Southeast Asia and the rest of the developing world, said Daniel Schrag, director of Harvard University's Center for the Environment. "I think it's possible for a few years but I think it's unlikely in the long run," he said.
The future trajectory of global emissions may hinge on whether wealthy, developed countries agree to fund clean energy development in India and other rapidly developing countries in the final week of negotiations in Paris.
"We are midway through the Paris talks, and [this paper] shows what is possible," Reay said. "We are really at that fork in the road, we could get back on to that climb upwards towards dangerous climate change, or we could start seeing a drop and that would be fantastic."
Schrag says there is little chance wealthy countries will agree to such funding. "The world is not going to pay India not to build coal plants," he said. "I think that is very unlikely."
The cost of inaction, however, would likely be even greater. Failure to reduce emissions now would likely mean an even more challenging remedy in the future: so-called "negative emission technologies" that pull large amounts of carbon dioxide out of the atmosphere in the future. Such yet-to-be developed technology carries significantly higher costs and risk, according to a second paper published by Jackson and others on Monday in the same issue of Nature Climate Change.
Ajay Mathur, the director of India's Bureau of Energy Efficiency, said his country would "absolutely" cut back on coal if it receives international support to reduce the cost of expanding renewable energy, according to recent news reports from Paris.
Such funding for India and other developing countries is becoming a sticking point in the Paris negotiations; still, a resolution could come yet this week.
It "will be a few more late-nighters, I think, before we get any clarification on absolute commitments for money from Paris," Reay said.