Worldwide greenhouse gas emissions will fall in 2015, in what would be the first time they have declined while economies continued to grow substantially, researchers have said,.
While emissions have fallen in previous years because of financial crashes, such as the global slump in 2007, this would be the first time that emissions have fallen at a time the world economy continued on a growth path, says the report published in the journal Nature Climate Change.
A decline in coal consumption by China, the world's carbon juggernaut responsible for more than a quarter of emissions, alone is projected to lower global carbon emission levels by 0.6 per cent this year. China's own emissions are expected to drop 3.9 per cent in 2015, after a decade of rising by nearly 6.7 per cent a year.
However, the report warns that the emissions fall may only be temporary and that a switch away from fossil fuels to clean sources of energy needs to be accelerated if dangerous warming is to be avoided.
''One wonders: is this peak emissions? It depends in large part in the immediate term on what happens in China, and how they deal with their economy instability and restructuring, what they call the 'new normal','' said Prof Corinne Le Quéré, director of the Tyndall Centre at the University of East Anglia and author on the paper.
''The Chinese themselves think their emissions are going to go up. So the prognosis for global emissions is also probably for resuming an upward trajectory.''
Rapid growth in emissions in other emerging countries dependent on coal, such as India, means that emissions are likely to go upward again in a few years. India, despite having a similar population to China, emits the same amount of greenhouse gases as China did 25 years ago.
''If history repeats itself and India becomes the new China in five-10 years, then the [global] emissions go up again,'' said Le Quéré.
India has emerged as a key player at the Paris talks. Prime Minister Narendra Modi has simultaneously pushed solar power as a way to cut emissions – signing up a global alliance of 120 countries to back the technology. But, at the same time, he signaled that India would not accept curbs on its development.
The new paper shows that Indian emissions in 2015 are likely to have shot up 6.7 per cent this year. Millions are still without access to electricity in India, and coal is expected to provide much of that new power.
Le Quéré said that while the global picture in 2015 was a welcome change to recent years of high growth, if emissions continue at such a level they would lead to disastrous warming, of 3-4 degree C above pre-industrial levels.
''It's really, really large warming. It means fundamental changes in rainfall patterns ... coastal areas would be impacted by sea level rises, both these things are pointing to increased risks of floods. That kind of warming level has a really strong influence on ecosystems and influence on risks for a range of pest and disease outbreaks.''
World leaders have agreed at previous climate talks to limit warming to 2C, and some countries at the current summit, including France and Germany, are fighting to have a goal of 1.5C enshrined in any Paris agreement.
''3-4C is pulling out the Earth really far from its natural equilibrium with the society and the way we have nature in relative balance now,'' Le Quéré said. ''2C is already pulling it away but at least it's not too much of a stretch. 3-4C is really big.''
However, the study did highlight signs of hope for bringing emissions from the power sector and industry down to zero, which is where scientists believe they must be by 2070 to avoid warming of more than 2C.
Solar and wind are highlighted as particular successes, with the amount of wind power installed in 2014 the same as the entire world capacity a decade ago. Nuclear is described as having been ''less successful'' in cutting emissions due to a stall in global capacity, while the report notes that ''little progress'' has been made on other technologies, such as carbon carbon and storage.
''Is this the beginning of the end of global warming? Probably not. But let's hope it is the end of the beginning,'' said Myles Allen, professor of geosystem science at the University of Oxford, who was not involved in the paper.
The study, Reaching Peak Emissions, said that emissions in 2015 were projected to be 35.7 gigatonnes (GT) of CO2 in 2015, down from 35.9 GT CO2 in 2014. Last year's stall happened despite global economic growth of 3.3-3.4 per cent a year during 2012-2014, and this year's decline with a forecast of economic growth at 3.1 per cent in 2015.
''This indicates that the old assumption of economic growth being dependent on rising fossil fuel use is broken. It should cheer anyone concerned that climate change might be insoluble, and encourage ministers meeting at the UN climate summit in Paris that pragmatic curbs on their carbon emissions are compatible with economic development,'' Richard Black, director of the UK-based thinktank, the Energy and Climate Intelligence Unit, said.
More than 185 countries submitted plans to cut emissions for the Paris climate talks, where ministers this week hope to reach a deal on Friday for cuts beyond 2020.