Speeding up political action is the most important factor in tackling climate change, according to new analysis.

The study by academics at research institutes IIASA, ETH Zurich and NCAR examined the probability of keeping average global temperatures from rising more than 2°C and claims limiting climate change will become much more difficult to achieve and more expensive if action is not taken soon. Two degrees is the level currently supported by more than 190 countries as a limit to avoid dangerous climate change.

The analysis suggested “the most important uncertainty is political” – the question of when countries will begin to take serious action to cut greenhouse gas emissions and implement other policies that could tackle climate change.

Keywan Riahi, IIASA Energy Programme Leader and study co-author said: “With a 20-year delay, you can throw as much money as you have at the problem and the best outcome you can get is a fifty-fifty chance of keeping temperature rise below two degrees.”

The study found social uncertainties like people’s awareness and choices on energy and the adoption of efficient technologies, which influence consumer energy demand, were second most important.

David McCollum, IIASA researcher and another co-author said: “How much energy the world consumes going forward turns out to be a much bigger swing factor for climate change than the availability of technologies like solar and wind power, biofuels and so on. Energy efficiency, improved urban planning, lifestyle changes – these things on the demand side of the energy equation are so important; yet they receive relatively little attention compared to the supply side.”

Geophysical uncertainties, which refer to the “unknowable” factors about how the climate system will react to greenhouse gas emissions and technological uncertainties, which are to questions about which energy supply and carbon capture systems will be available in the future ranked below political and social uncertainties.