Nonlinearities are an important consideration in evaluating risk management combinations. Nonlinearities have been estimated in global and regional mitigation costs and potential economic damages from climate change  ; . Nonlinear mitigation costs mean increasingly higher costs for each additional incremental reduction in emissions . Nonlinear increases in estimated economic climate damage means increasingly higher damages for each additional incremental increase in climate change . However, the evidence on whether damages increase at an increasing or decreasing rate is mixed . Nonlinearities are also suggested in estimated changes in key risks and adaptation costs . However, to date, they have not been as explicitly characterised. These nonlinearities imply nonlinearities in climate risk management synergies and trade-offs with sustainable development. Not only do trade-offs vary by climate level, as do synergies, but they increase at an increasing rate and their relative importance can shift across climate levels . Some of this is evident in results such as those shown in Figure 18.5 for mitigation . Uncertainty about the degree of nonlinearity in mitigation, climate damages, key risks and adaptation costs creates uncertainties in the strength of the trade-offs and synergies, but also represents opportunities. For instance, additional mitigation options and more economically efficient policy designs have been shown to reduce mitigation costs and the nonlinearities in mitigation costs  . The same is true for adaptation options and adaptation costs.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report