A theory of TPs and their early warning signs is well-established for slowly varying systems that are close to being autonomous, based on behaviour near bifurcation points in stochastically perturbed dynamical systems [Ashwin et al., 2012; Kuehn, 2013]. However, this theory is not always adequate for the problem of abrupt climate changes for a variety of reasons. There may be no effective time scale separation, the behaviour in idealized models may not be present in more detailed models and systems may be non-autonomous over a range of timescales. Considerations become even more complicated for the control problem of assessing the impact of emissions scenarios and avoidance of crossing planetary boundaries to sustainable development.
This work package aims to extend the theory of TPs taking into account transient climate change, making use of recent developments in the theory of non-autonomous and random dynamical systems. In particular it will work to expand and apply this theory in a purpose-specific way that applies to the commonly used climate modelling methodologies, from conceptual deterministic temporal models to stochastic spatio-temporal models. The concrete objectives of this WP are:
- To understand the robustness of TPs across the climate model hierarchy.
- To further develop and apply non-autonomous dynamical systems theory appropriate to understand climate tipping phenomena in the presence of a variety of GHG emissions scenarios.
- To develop and evaluate novel early warning signals (EWS) for non-autonomous climate problems and associated statistical forecasting and detection tests.