Feeling lucky? Spin these roulette wheels and see where the future lies: on the left, if the world takes decisive action to reduce emissions over the next 100 years, and on the right if we don’t. If we do: most likely an increase of 2 – 2.5ÂºC. If we don’t: most likely is 5 – 6ÂºC. Produced by the Joint Program on the Science and Policy of Global Change at MIT, the wheels are a novel way to express the uncertainties associated with projections of future climate and the way they interact with policy decisions. The message for policy makers is clear, according to study co-author Ronald Prinn:
“There’s no way the world can or should take these risks,” Prinn says. And the odds indicated by this modeling may actually understate the problem, because the model does not fully incorporate other positive feedbacks that can occur, for example, if increased temperatures caused a large-scale melting of permafrost in arctic regions and subsequent release of large quantities of methane, a very potent greenhouse gas. Including that feedback “is just going to make it worse,” Prinn says.
Climate change deniers hate these models. Why, they say, should we base current policy on scenarios and computer programmes rather than observable facts? But that’s the trouble with the future: you can’t observe it. If you reject the world’s most sophisticated models as a means of forecasting likely climate trends, you must suggest an alternative. What do they propose? Gut feelings? Seaweed? Chicken entrails?
Tea leaves, obviously…