More so than in previous reports, the IPCC focuses on the possibility that the climate may change in a manner that is irreversible. Professor of “tipping points” Marten Scheffer has spent a lifetime studying such systems.
Is the climate subject to tipping points?
‘Certainly. Research by our former PhD Vasilis Dakos shows that eight known climate changes are the result of tipping points. Models also suggest that the climate has certain tipping points. Our current data -changes in the warm gulf stream, for example- show evidence of such tipping points.’
It can no longer be ignoredMarten Scheffer
Nonetheless, the IPCC report states that there is ‘limited’ evidence that the global climate is approaching a tipping point.
‘That depends on what you consider evidence of a tipping point. There is no single tipping point for the entire climate, but rather various local tipping points. In well-known sub-systems such as the Amazon rainforest, the warm gulf stream or the ice caps, self-amplifying effects could lead to a tipping point. The problem is that it is difficult to determine whether we are close to a tipping point. Change may be gradual and slow. Many parts of the climate, such as melting ice caps, have a long timeline. A turnaround point may well take centuries.’
Is the absence of such a global tipping point good news?
‘Well, I wouldn’t put it that way. Local tipping points also have serious consequences. Suppose the warm gulf stream decreases or even stops entirely. This has significant effects on our climate, but also on monsoon rains, for example.’
Is there any good news?
‘The good news is that it is still possible to keep the temperature increase limited to 1.5 degrees Celsius. This IPCC report will be the last in which this is still possible. In six years, it will be too late. The fact that the clear message in this report appears simultaneously with global extreme weather and a few months before the Glasgow climate summit is also good news. The warning from scientists and the developments outside could not be any clearer.’
So, it is still possible?
‘Yes. But the IPCC report also shows how things can go wrong with unprecedented clarity. If we do not act, the world will change tremendously. It can no longer be ignored.’