Carbon dioxide emission reductions required to limit global warming to 2C are becoming a receding goal based on new figures reported in the latest Global Carbon Project (GCP) calculations published in the advanced online edition of Nature Climate Change. "A shift to a 2C pathway requires an immediate, large, and sustained global mitigation effort," GCP executive-director and CSIRO co-author of the paper, Dr Pep Canadell said.

Global CO2 emissions have increased by 58 per cent since 1990, rising 3 per cent in 2011, and 2.6 per cent in 2012. The most recent figure is estimated from a 3.3 per cent growth in global gross domestic product and a 0.7 per cent improvement in the carbon intensity of the economy.

Dr Canadell said the latest carbon dioxide emissions continue to track at the high end of a range of emission scenarios, expanding the gap between current trends and the course of mitigation needed to keep global warming below 2C.

He said on-going international climate negotiations need to recognise and act upon the growing gap between the current pathway of global greenhouse emissions and the likely chance of holding the increase in global average temperature below 2C above pre-industrial levels.

The research, led by Dr Glen Peters from CICERO, Norway, compared recent carbon dioxide emissions from fossil fuel combustion, cement production, and gas flaring with emission scenarios used to project climate change by the Intergovernmental Panel on Climate Change (IPCC).

"We need a sustained global CO2 mitigation rate of at least 3 per cent if global emissions are to peak before 2020 and follow an emission pathway that can keep the temperature increase below 2C," Dr Peters said.

"Mitigation requires energy transition led by the largest emitters of China, the US, the European Union and India".

He said that remaining below a 2C rise above pre-industrial levels will require a commitment to technological, social and political innovations and an increasing need to rely on net negative emissions in future.

The Global Carbon Project, supported by CSIRO and the Australian Climate Change Science Program, generates annual emission summaries contributing to a process of informing policies and decisions on adaptation, mitigation, and their associated costs. The summaries are linked to long-term emission scenarios based on the degree of action taken to limit emissions.