More carbon pollution was spewed into the air globally last year than ever before, chiefly due to China, the U.S. and India, scientists announced as world leaders gathered today in New York City ahead of tomorrow's opening of the UN Climate Summit.

More than 100 world leaders will attend the summit to discuss how to reverse the emissions trend.

According to new scientific reports, the world pumped an estimated 36.1 billion tonnes of carbon dioxide into the air last year by burning coal, oil and gas. That is 706 million tonnes, or 2.3 per cent more, than the previous year.

"It's in the wrong direction," said Glen Peters, a Norwegian scientist who was part of the Global Carbon Project international team that tracks and calculates global emissions every year.

Their results were published Sunday in three articles in the peer-reviewed journals Nature Geoscience and Nature Climate Change.

The team projects that emissions of carbon dioxide (CO2), the main heat-trapping gas from human activity, are increasing by 2.5 per cent this year.

The scientists forecast that emissions will continue to increase, adding that the world in about 30 years will warm by about 1.1 C from now. In 2009, world leaders called that level dangerous and pledged not to reach it.

"Time is running short," said Pierre Friedlingstein of the University of Exeter in England, one of the studies' lead authors. "The more we do nothing, the more likely we are to be hitting this wall in 2040-something."

Chris Field, a Carnegie Institution ecologist who heads a UN panel on global warming, called the studies "a stark and sobering picture of the steps we need to take to address the challenge of climate change."

No countries came close to China, India, U.S.

The world's three biggest carbon-polluting nations — China, the U.S. and India — all saw their emissions jump. No other country came close in additional emissions:

When the extra leap day in 2012 is accounted for:

  • Chinese emissions grew by 4.2 per cent to 10 billion tonnes.
  • U.S. emissions grew by 2.9 per cent to 5.2 billion tonnes.
  • Indian emissions grew by 5.1 per cent to 2.4 billion tonnes.

China, the No. 1 carbon polluter, also had more than half the world's increases over 2012. China's increases are slowing because its economy isn't growing as fast as it had been, Peters said.

The U.S. had reduced its carbon emissions in four of the five previous years. Peters said it rose last year because of a recovering economy and more coal power.

Canada's emissions increased one per cent last year to 503 million tonnes, making it the 10th biggest carbon emitter in the world.

Only two dozen of the about 200 countries cut their carbon emissions last year, led by mostly European countries. Spain had the biggest decrease.

The world emissions averaged to 2.9 million kilograms of carbon dioxide put in the air every second.