Repeated Warning Signals for Sudden Climate Warming Consequences on Possible Sustainability Policies

Climate evolution is revisited in terms of the Theory of Dynamical Systems, successfully used in predictions of catastrophic events as avalanches, landslides, or economy and civilization collapses. Such tippings are announced by warning signs, named “critical softening”, allowing a tipping date estimate through well-known equations. In the case of climate the warning signs are extreme events of increasing amplitudes. In such a context, numerical simulations cannot predict incoming tipping points, due to a divergence of computational time at the singularity. This is probably the reason why numerical predictions are systematically revised upwards with every new IPCC report. Based on such warning signals, a recent publication of Copenhagen University shows that the Atlantic Meridional Oceanic Circulation is likely to collapse well before the end of the century, triggering switchover cascades, eventually culminating in global climate tipping. Paleoclimatic studies also show that tippings occurred in the past, particularly during the PETM event 56 Myrs ago. If this was to happen now, average global temperatures might reach an unbearable level, with a deadline much closer than expected. This extreme emergency has major consequences on implementation times of sustainability policies, in energy production, mobility, agriculture, housing …, that absolutely must be operational on time.