And at the bottom of the mathematical debate is a question of utility: Would the existence of a real planetary-scale tipping point change how we should confront our environmental challenges, from energy sources to land use?
A more accurate picture would not just let us prepare for rapid climate change, but might help us predict it as well. Marten Scheffer, of Wageningen University in the Netherlands, has done extensive work on ways we can see tipping points coming. On smaller scales, he says, a system can exhibit “critical slowing down”—a slowed ability to recover from perturbations—before jumping to the irreversible new state. Scheffer says, arguing for tipping points, that past global-scale, quick changes in climate appear to have exhibited a similar effect.
And if we agree a tipping point can exist, maybe we can even try and stave it off. As the world seems to be inching closer to addressing climate change, identifying specific targets for the most effective mitigation grows ever more important. In his recent State of the Union speech, Pres. Barack Obama called for unilateral action to address global warming–related emissions; if we can find a tipping point threshold, is that reason to adjust such action to reflect the possibility of rapid global-scale change?
“If there is plausibility to one of these tipping points, which I think there is, then it’s an even more urgent matter to act to slow all of these individual stressors down,” U.C. Berkeley’s Barnosky says, “because the outcomes could be more surprising and more disruptive to society, and happen faster than we have time to react…. I’d much rather err on the side of precaution then ignore the possibility of tipping points and then be unpleasantly surprised when they happen.”