Sensitivity and resilience of the climate system: A conditional nonlinear optimization approach

In this paper, we propose the concepts of conditional climate resilience and conditional climate sensitivity as measures of the nonlinear response of a non-stationary background climate state to arbitrary perturbations. Based on the theory of nonlinear stability, we formulate both sensitivity and resilience in terms of a conditional nonlinear optimization problem. As illustrated by results of a zero-dimensional energy balance model, the new measures provide useful information of sensitivity and resilience of the climate system in the presence of bifurcations and under non-stationary external forcing.