– IIASA News Release
Limiting climate change to target levels will become much more difficult to achieve, and more expensive, if action is not taken soon, according to a new analysis from IIASA, ETH Zurich, and NCAR.
The new study, published this week in the journal Nature, examined the probability of keeping average global temperatures from rising more than 2°C above preindustrial levels under varying levels of climate policy stringency, and thus mitigation costs. In addition, the study for the first time quantified and ranked the uncertainties associated with efforts to mitigate climate change, including questions about the climate itself, uncertainties related to future technologies and energy demand, and political uncertainties as to when action will be taken.
The climate system itself is full of uncertainty – an oft–used argument to postpone climate action until we have learned more. “We wanted to frame the problem in a new way and try to understand which uncertainties matter in trying to limit global warming by specific climate action,” said Joeri Rogelj, ETH researcher and lead author on the paper, who carried out the research at IIASA.
The most important uncertainty, according to the study, is political – that is, the question of when countries will begin to take serious action to reduce greenhouse gas emissions and implement other policies that could help mitigate climate change. Keywan Riahi, IIASA energy program leader and study co-author said, “With a twenty-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.” Two degrees is the level that is currently supported by over 190 countries as a limit to avoid dangerous climate change.
Social uncertainties, which influence consumer energy demand, were second-most important, the study found. Social uncertainties refer to things like people’s awareness and choices with respect to energy and to the adoption of efficient technologies.