Global economic growth did not translate into more harmful greenhouse gas emissions from the energy sector last year, the IEA said on Wednesday, a strong indication that growth and increased pollution no longer go hand in hand.

For the second year running, worldwide CO2 emissions stalled in 2015 while the global economy grew by 3.1 percent, after a 3.4-percent rise in 2014, the International Energy Agency said.

A surge in the contribution from renewable energy sources explains the decoupling of growth and CO2 emissions, with clean energy sources accounting for 90 percent of all new electricity generation in 2015.

Wind alone contributed half of all new electricity generation, the IEA said.

"We now have seen two straight years of greenhouse gas emissions decoupling from economic growth," IEA Executive Director Fatih Birol said in a statement.

"Coming just a few months after the landmark COP21 agreement in Paris, this is yet another boost to the global fight against climate change."

There have been four instances of falling CO2 emissions year-on-year in the last four decades, three of which coincided with economic weakness, in contrast to the scenario seen these past two years.

The two largest greenhouse gas emitters, the United States and China, both registered declines in CO2 production in 2015.

But this was offset by increased emissions in other Asian developing countries, the Middle East and, to a less extent, in Europe, keeping the overall emissions level flat, the IEA said.

Environmental organisation Greenpeace called the IEA's findings "encouraging", saying they were "a sign that national climate and renewable energy policies are working".

But in a statement, it also said that emissions now need to be brought down.

"Few steps have been taken to accelerate clean energy deployment so emissions start to decline," Greenpeace International Global Energy Strategist Emily Rochon said in a statement.

"World leaders now need to double down on making sure global temperature increase remains within the limits agreed in last year's Paris Agreement," added Li Shuo, Greenpeace East Asia senior climate adviser.

Greenpeace also noted that "Europe is the only region in the world that saw investments in renewable energy, particularly wind and solar, decline in the last five years".

The 29-nation IEA provides analysis on global energy markets and advocates policies enhancing the reliability, affordability and sustainability of energy.