Glimpses of nonlinear dynamics in climate change science

COLLOQUIUM TALK

Title: Glimpses of nonlinear dynamics in climate change science

Abstract: We will provide a glimpse of a few different problems in nonlinear climate dynamics, all of which impinge on the design and use of model hierarchies to investigate problems of climate stability and climate change. We will first give a glimpse of nonlinear dynamics of monsoons, in context of questions about whether the South Asian monsoon is a tipping element of the Earth system, reconciling the absence of tipping dynamics with an explanation for the abrupt seasonal onset of the monsoon. We will consider a low-order model of coupled weather-climate interactions to study ocean overturning circulation dynamics, which exhibits intermingled basins, to explore questions of initial condition sensitivity and model uncertainty, and implications for long-term prediction of slow climate variables. Thirdly, we will discuss the nonlinear dynamics of Volterra gyrostats, which naturally give rise to coupled hierarchies of low order models obtained through model reduction techniques. We will discuss some results from recent work on low-dimensional chaos and briefly speculate on how these models might be used to probe a range of relevant topics related to uncertainty across modelling hierarchies. Amidst this we will discuss wider examples of how tools from nonlinear dynamics are being used in climate change research.