A new analysis of climate risk has shown that even moderate carbon-reduction policies now can substantially lower the risk of future climate change.
To illustrate the findings of their model, MIT (Massachusetts Institute of Technology) researchers created a pair of 'roulette wheels.'
This wheel depicts their estimate of the range of probability of potential global temperature change over the next 100 years if no policy change is enacted on curbing greenhouse gas emissions.
It shows that quick, global emissions reductions would be required in order to provide a good chance of avoiding a temperature increase of more than 2 degrees Celsius above the pre-industrial level - a widely discussed target.
But without prompt action, they found, extreme changes could soon become much more difficult, if not impossible, to control.
According to Ron Prinn, co-director of MIT's Joint Program on the Science and Policy of Global Change and a co-author of the new study, said that "our results show we still have around a 50-50 chance of stabilizing the climate" at a level of no more than a few tenths above the 2 degree target.
However, that will require global emissions, which are now growing, to start downward almost immediately.
That result could be achieved if the aggressive emissions targets in current US climate bills were met, and matched by other wealthy countries, and if China and other large developing countries followed suit with only a decade or two delay.
That 2 degree Celsius increase is a level that is considered likely to prevent some of the most catastrophic potential effects of climate change, such as major increases in global sea level and disruption of agriculture and natural ecosystems.
"The nature of the problem is one of minimizing risk," explained Mort Webster, assistant professor of engineering systems, who was the lead author of the new report.
hat's why looking at the probabilities of various outcomes, rather than focusing on the average outcome in a given climate model, "is both more scientifically correct, and a more useful way to think about it," he added.
One interesting finding the team made is that even relatively modest emissions-control policies can have a big impact on the odds of the most damaging climate outcomes.
"These results illustrate that even relatively loose constraints on emissions reduce greatly the chance of an extreme temperature increase, which is associated with the greatest damage," the report concluded.