The world pumped an estimated 39.8 billion tons of carbon dioxide into the air last year by burning coal, oil and gas. That is 778 million tons 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.
The team projects that emissions of carbon dioxide, 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 degrees Celsius from now. In 2009, world leaders called that level dangerous and pledged not to reach it.
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"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."
More than 100 world leaders will meet Tuesday at the UN Climate Summit to discuss how to reverse the emissions trend. The world's three biggest carbon polluting nations China, the US and India, all saw their emissions jump. No other country came close in additional emissions.
Indian emissions grew by 5.1 per cent, Chinese emissions by 4.2 per cent and the U S emissions by 2.9 per cent, when the extra leap day in 2012 is accounted for.
China's increases are slowing because the Chinese economy isn't growing as fast as it had been, Peters said.
The US 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.