Carbon emissions may have peaked already in China, years earlier than its leaders pledged, according to a study co-authored by the world-renowned economist Lord Stern.

The country’s emissions have fallen, partly as a result of its globally relevant economic slowdown, and partly owing to government policies to pursue a low-carbon path and reduce the rampant air pollution in its major cities.

If this trend continues it would show that the country’s emissions have already peaked, said Fergus Green, lead author of the report from the LSE.

This would be a landmark in international efforts to tackle emissions and fight climate change, formalised in last December’s breakthrough international accord on climate change signed in Paris. At the summit China, the world’s second biggest economy and the largest emitter of greenhouse gases, agreed that its emissions should peak by 2030.

In the new report, Green and Stern argue that if China’s emissions have not already peaked, then they are very likely to do so within the next decade, bringing the world’s biggest emitter to its internationally agreed target years earlier than expected.

This is an important development, as it means that the world’s biggest emitter is likely to be finally on a downward path of carbon emissions. Although there is a possibility that China’s emissions will pick up if its growth rate recovers, the reduction in emissions is likely to continue, according to Green.

“We are seeing a larger infrastructural change in China,” Green told the Guardian. This was the result of policies and changing industrial conditions, he said. A fall in China’s coal consumption in 2014 accelerated in 2015, according to government statistics published in February.

Facebook Twitter Pinterest Coal use in China fell 3.7% in 2015, following 2.9% drop in 2014, according to government statistics. Photograph: Jason Lee/Reuters

Green also discounted the idea that a reduction in emissions in China, as it moves to a higher value economy rather than the low-wage, high-production model that has fuelled in its past two decades of high growth, would be wiped out by an increase in emissions in other developing economies that are following China’s example.

“It is almost inconceivable [that other countries would make up for these emissions], because China is so large,” he said.

Under the Paris agreement, all countries - developed and developing - are called on to review their emissions targets every five years. Green said this could be key to reducing emissions further. “One of the virtues of the current agreement is the review mechanism, so China will be in a very strong position in 2020 to ratchet up its targets,” he said.

In Europe, however, green campaigners were disappointed last week by a report from the European commission that focused on the core Paris commitment to cut emissions in line with a 2C rise in temperatures. Governments in Paris had also pledged to consider how to cut their carbon in order to limit temperature rises to no more than 1.5C , which would avoid more of the ravages of climate change, particularly on small islands at risk from rising sea levels, but which would be harder to meet.

Bram Claeys, EU climate and energy policy advisor for Greenpeace, said: “The Commission must stop pretending Paris didn’t happen. It has a responsibility to step up climate action to reflect the Paris deal in legislation on renewables and energy efficiency. People won’t trust the EU if it continues to play fast and loose with global warming and delays Europe’s shift to 100% renewable energy.”

On Friday, at a meeting of EU environment ministers, several countries pushed for a stronger 2030 emissions target from the EU than the one agreed at Paris. This was welcomed by green campaigners.

Genevieve Pons, director of the European policy office of WWF, said: “We have seen huge support from member states for increasing the EU’s 2030 climate and energy targets. Doing so is the only way of standing by our commitments in Paris, working to limit temperature rises to 1.5C. EU countries have injected a welcome dose of ambition into the climate discussion, after the Commission’s lacklustre input.”