After 2009's dip in carbon emissions caused by the world economic crisis, levels hit a record high last year.
According to the latest estimates by the International Energy Agency (IEA), emissions are estimated to have climbed to a record 30.6 Gigatonnes (Gt), five percent higher than 2008's previous record.
The findings cast grave doubt on countries' ability to hit 2010 emissions targets: some 80 percent of projected emissions from the power sector in 2020 are already locked in, as they'll come from power plants that are currently in place or under construction today.
"This significant increase in CO2 emissions and the locking in of future emissions due to infrastructure investments represent a serious setback to our hopes of limiting the global rise in temperature to no more than 2ºC," says Dr Fatih Birol, the IEA's chief economist.
The 2°C target was agreed at the UN climate change talks in Cancun in 2010 - but relies on the long-term concentration of greenhouse gases in the atmosphere staying below 450 parts per million of CO2-equivalent, only five percent up from 2000. For things to go to plan, global energy-related emissions in 2020 must not be greater than 32 Gt.
However, to achieve this, over the next ten years, emissions would have to rise less in total than they did between 2009 and 2010 - something that today's figures show is highly unlikely.
"Our latest estimates are another wake-up call," says Dr Birol. "The world has edged incredibly close to the level of emissions that should not be reached until 2020 if the 2ºC target is to be attained."
Most of the growth came from developing countries. While 40 percent of global emissions came from OECD countries in 2010, these countries showed an increase of only 25 percent compared to 2009. Non-OECD countries – led by China and India – saw much stronger increases as their economic growth accelerated.
However, on a per capita basis, OECD countries collectively emitted 10 tonnes, compared with 5.8 tonnes for China, and 1.5 tonnes in India.