I am fascinated by the co-evolution of the Earth, life, and human societies as a complex and dynamic system and what we can learn from this about how best to live on the Earth. I use dynamical system models and numeral analysis to explore how the Earth system functions and evolves, focusing on topics ranging from past perturbations to the carbon-climate system, the puzzle of Earth’s long-term habitability, through to the behaviour and resilience of socio-ecological systems in the present.
Since the Earth formed some ~4.6 billion years ago it has experienced many dramatic changes, from the formation of the oceans and then continents to the emergence of life itself at least 3.8 billion years ago. This history presents a puzzle: how did life survive for so long on despite repeated mass extinctions and the threat of long-term climate change? The sun has grown some 30% hotter over those ~4.6 billion years, but despite some large fluctuations the Earth’s climate has not grown hotter in parallel. Is this the impact of life (the self-regulating homoeostasis of ‘Gaia’), a geochemical inevitability (the drawdown of CO2 by the slow dissolution of silicate rocks), or just sheer chance (we’re just the observers lucky enough to be alive to ask the question)? Now humans are causing changes more rapid than the Earth has experienced for many millions of years. What can we do to ameliorate our impact, and what happens if we don’t?
Earth system science aims to answer these questions by examining the relationships between all of the Earth’s processes (including humans forming socio-ecological systems in recent times), while complexity science gives us useful tools for analysing and understanding complex dynamical systems such as the Earth system. The emergent theme is Earth system resilience: the degree to which the Earth system can quickly recover from short-term perturbations and return to its previous state. High resilience implies an ability for a system to withstand shocks, whereas declining resilience would leave the system vulnerable to passing ‘tipping points’ beyond which regime shifts to a new state becomes inevitable.
My research takes Earth system resilience as a central theme, and covers topics including Palaeoclimate change and the Carbon Cycle (in particular during the last 66 million years, when the Earth moved from a ‘Greenhouse’ to ‘Icehouse’ climate), Earth System Models of the Anthropocene (focusing on climate-biosphere feedbacks), Sustainable Socio-Ecological Systems (such as the sustainable intensification of agroecosystems), and potential metrics of Resilience, Tipping Points, & Early Warnings. You can find a list of current publications coming out of this research here.