PROMOTE stands for “Progressing Earth System Modelling for Tipping Point Early Warning Systems” and is a 5-year research project funded under the ARIA’s Forecasting Tipping Points programme. In PROMOTE, we will conduct climate research and modelling to study two parts of the climate system thought to be at risk of tipping: the North Atlantic subpolar gyre (SPG) and the Greenland Ice Sheet (GrIS). We aim to answer some central questions about these two systems: What are the risks of plausible tipping points involving SPG collapse or rapid GrIS loss occurring? How will such tipping happen and what impacts would it have, for example in the North Atlantic ocean and for European weather and climate? How should observational platforms be deployed to detect signs that we are approaching a tipping point?

Because such tipping has not been observed in the instrumental record, physically-based computer simulation is key to addressing these questions. Presently, the only way to simulate plausible tipping points is to use Earth System Models (ESMs) that represent the complex, nonlinear processes fundamental to these tipping systems. In PROMOTE, we will use the UK Earth System Model (UKESM). UKESM is already a world leading ESM in that it contains dynamic and interactive Greenland and Antarctic ice sheets. We will undertake targeted model development to further improve the representation of the GrIS and SPG in UKESM, thus developing an ESM that can serve as the physical model component of a future proof-of-concept tipping point early warning system. These developments will focus on the energy balance at the surface of the GrIS, the export of solid ice and freshwater from the GrIS into the North Atlantic, and the mixing of water masses in the ocean. We will also test the effect of increased model resolution in the ocean and atmosphere.

We will use our newly developed UKESM versions to conduct model experiments of SPG and GrIS tipping. In this context, we will test innovative methods to make the simulation of tipping behaviour more efficient and controlled. We will use these simulations to address the above research questions about tipping risk and impacts, and make our simulations available to the ARIA community of researchers. In one area of work, we will determine how to – according to our model – best make observations to detect or predict tipping, thus informing the design and deployment of observational instruments by other projects in the ARIA FTP programme.