There has been a "decoupling" of energy-related carbon dioxide emissions from economic growth over the last two years, according to the International Energy Agency.

The Paris-based group that monitors global energy needs says the amount of carbon dioxide emitted over the past two years has flattened, coming in at 32.1 billion tonnes in 2015, about the same as 2013 and 2014.

Meanwhile global GDP grew by 3.4 per cent in 2014 and 3.1 per cent in 2015.

"The new figures confirm last year's surprising but welcome news: we now have seen two straight years of greenhouse gas emissions decoupling from economic growth," IEA executive director Fatih Birol said in a news release.

The change is because of the rapid adoption of renewable energy, especially for electrical generation, the IEA said.

Electricity generated by renewables accounted for around 90 per cent of new electricity generation in 2015, with wind alone producing more than half of new electricity generation.

The IEA's conclusion that economic growth can continue without needing increased amounts of fossil fuels is preliminary, like its data, which will be explored in a more complete report in June.

China, U.S. emit less CO2

Two of the world's largest emitters have been making the transition from coal generation to renewables.

In China, CO2 emissions declined by 1.5 per cent and in the U.S., emissions declined by 2 per cent. China's official growth figure is 6.9 per cent for 2015 while the U.S. latest estimate is 2.4 per cent.

The declines in China and the U.S. were offset by increased emissions in other Asian developing countries, the Middle East and a moderate increase in Europe.

There has been concern among the economists about a slowing of global growth in the past two years and fears that the agreement to curb carbon emissions reached in Paris last fall might weigh heavily on GDP around the world.

The IEA points out that in other periods when emissions flattened or fell – such as the early 1980s, 1992 and 2009 – there was global economic weakness.

Critics say there will be limits to what renewables can achieve as it becomes harder to get consistent electricity generation when renewables make up a larger part of the system.

However, there is still a lot of low-hanging fruit to pick in the move to control greenhouse gases, including control of methane emissions as proposed by a pact between Canada and the U.S.