Carbon dioxide emissions from burning fossil fuels have soared in the last 20 years, giving the world much less chance of avoiding dangerous climate change, new data show.
The research was published as lead negotiators were arriving at the UN climate talks in Durban, South Africa, where prospects of a new global treaty on climate change appeared to have stalled, with deep divisions between developed and developing countries.
Emissions from burning fossil fuels rose by 5.9% in 2010, bringing the total rise since 1990 - the baseline year for calculating emissions under the Kyoto protocol - to 49%. Measured over two decades, that is an average annual increase of 3.1%.
Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research at the University of East Anglia, and an author of the research, said the data showed that little had been achieved over 20 years in reducing the risks from climate change.
"There have been efforts to use more renewable energy and improve energy efficiency but what this shows is that so far, the effects have been marginal," she said. "We need to do something about the 80% of energy that still comes from burning fossil fuels."
She said the problem was urgent, as the chances of holding global temperature rises to less than 2 degrees Celsius above pre-industrial levels beyond which climate change becomes catastrophic and irreversible, were dependent on emissions peaking by 2020 at the latest. Scientists regard the 2-degree target as the limit of safety.
Governments meeting in Durban this week are focusing on a new treaty that, if it can be achieved, would not come into force until 2020. "That would be too late, unless strong actions are taken in the meantime," said Le Quéré.
Some governments and policy advisors have been advocating a different approach to the climate negotiations, suggesting that a system of voluntary reductions in emissions undertaken by national governments and industries could be more effective than a "top-down" global treaty. But this so-called "bottom-up" approach did not appear to be working currently, Le Quéré said, as efforts to cut emissions so far had little impact outside Europe, where emissions have been successfully reduced.
The study, published in the peer-reviewed journal Nature Climate Change, found that global carbon emissions were likely to carry on increasing at a rate of about 3% per year. It was accompanied by another study offering new proof that climate change is linked to human activities, including burning fossil fuel.
Chris Rapley, professor of Climate Science at University College London, said: "These two new results offer a stark message. Human carbon emissions are certainly disturbing the climate system upon which we depend, and in spite of the economic slowdown, and despite all the efforts by governments, businesses and people to reduce them, our emissions are reaching new highs. The climatic consequences, already emerging, will grow over time, and are irreversible.
"A new level of decisive action is required now to achieve real emissions reductions. World leaders at the climate negotiations at Durban know the score; the opportunity to act consistent with their responsibilities and rank lies before them. We can only hope that they rise to the challenge."
Julia Steinberger, lecturer in ecological economics at the Sustainability Research Institute, University of Leeds, said the research showed that even the recession had barely made a dent on the rise in greenhouse gas emissions.
"The worst economic crisis in decades was apparently a mere hiccup in terms of carbon emissions: a temporary drop for the richest countries in 2009, and hardly perceived by emerging economies," Steinberger said. "These findings are truly shocking, and constitute a global wake-up call.
"The economic crisis should have been an opportunity to invest in low-carbon infrastructure for the 21st century. Instead, we fostered a lose-lose situation: carbon emissions rocketing to unprecedented levels, alongside increases in joblessness, energy costs and income disparities. Surely the transition to a green economy has never seemed more appealing."