The predictability barrier of climate instabilities

Abstract Anthropogenic warming bears the risk of climate instabilities, some of which might have already been initiated. Due to their multidecadal to millennial transition times, their interaction with weather has rarely been investigated and their discounted economic impact has been considered relatively low. Here we show that (1) even rapidly changing, i.e. weather-induced, forcing influences systems with multidecadal collapse times such as the Atlantic overturning and the Amazon rainforest, (2) approaching their tipping temperature immediately increases weather-induced volatility long before the tipping point is reached and well after the tipping point is passed, (3) unpredictability of these systems is further increased by noise-enhanced tipping and (4) for multidecadal systems variability increases by up to 120\% and unpredictability by more than 300\%. The faster the internal system time the stronger the increase in variability and unpredictability. Thus, in addition to the fundamental long-term changes, volatility poses an immediate societal and economic risk from climatic tipping that is directly related to the tipping process itself.