PhD position in climate dynamics and earth system modelling (1.0 FTE)

Concerns are rising that several subsystems of the Earth may respond highly nonlinearly to future levels of anthropogenic forcing from greenhouse gas emissions. These levels are associated with tipping elements such as the Atlantic Ocean circulation, leading to abrupt transitions. As tipping elements are coupled, cascades of abrupt transitions can occur and affect the whole climate system. The mechanisms leading to such cascading behaviour and in particular the physical links between tipping elements are poorly understood. Tipping cascades are high impact events, which urgently need to be understood to estimate the associated societal, economic and environmental risks. This knowledge is also needed to develop emission targets minimizing risks of harmful transitions to undesired states of the Earth system in line with the Paris climate agreement. The aim of this project is to quantify the physical links between specific tipping elements and assess the likelihood of initiating tipping cascades within this century. Our team will identify positive feedbacks between tipping elements that could lower critical atmospheric CO2-levels, and quantify the expected climate response in the presence of cascading tipping behaviour.

For this PhD position you will work on developing the mathematical theory of coupled tipping elements beyond the basic bifurcation induced tipping. In particular, the aim is to extend the analysis to two-way coupled non-autonomous stochastic systems, where in addition to bifurcation induced tipping noise-induced transitions as well as rate-dependent tipping can occur. Examples of tipping elements to be coupled using conceptual models of each include the Atlantic Meridional Overturning Circulation, El Niño-Southern Oscillation and polar ice sheets. Within the team, you will work closely together with a Postdoc who, in this project, will focus on quantifying physical links between different tipping elements. The vacancy for this Postdoc position is posted simultaneously on the website of Utrecht University.

The project is funded through a NWO-Vici grant to Anna von der Heydt. You will work in a multidisciplinary team on the project objectives using numerical simulation and theory development. We will employ a full climate model hierarchy – from conceptual models to the most complex state-of-the-art climate models – to track cascading tipping behaviour. We also work in collaboration with colleagues from EU-H2020 project TiPES and EU-ITN CriticalEarth , as well as the Centre for Complex Systems Studies at Utrecht University.