Setting up the physical principles of resilience in a model of the Earth System

TL;DR

This work defines physical resilience for the Earth System within a thermodynamical framework by extending a Landau-Ginzburg model with a cubic term in the free energy and dissipative dynamics. It shows how metastable states and energy dissipation, arising from PB interactions and a cubic nonlinearity in $F(\psi,H)$, can bound ES trajectories and prevent a transition to a Hothouse Earth. The model introduces a tunable anthropogenic forcing $H$, which policy actions (mitigation, transformation, restoration) can shape to realize resilient states characterized by $(\psi_M,h_{iM})$ under specific stability conditions. The results link PB dynamics to resilience, highlighting urgent, multi-faceted governance to steer the Anthropocene away from irreversible climate tipping points.

Abstract

Resilience is a property of social, ecological, social-ecological and biophysical systems. It describes the capacity of a system to cope with, adapt to and innovate in response to a changing surrounding. Given the current climate change crisis, ensuring conditions for a sustainable future for the habitability on the planet is fundamentally dependent on Earth System (ES) resilience. It is thus particularly relevant to establish a model that captures and frames resilience of the ES, most particularly in physical terms that can be influenced by human policy\footnote{See page 4 for examples of strategies}. In this work we propose that resilience can serve as a theoretical foundation when unpacking and describing metastable states of equilibrium and energy dissipation in any dynamic description of the variables that characterise the ES. Since the impact of the human activities can be suitably gauged by the planetary boundaries (PBs) and the planet's temperature is the net result of the multiple PB variables, such as $\text{CO}_2$ concentration and radiative forcing, atmospheric aerosol loading, atmospheric ozone depletion, etc, then resilience features arise once conditions to avoid an ES runaway to a state where the average temperature is much higher than the current one. Our model shows that this runaway can be prevented by the presence of metastable states and dynamic friction built out of the interaction among the PB variables once suitable conditions are satisfied. In this work these conditions are specified. As humanity moves away from Holocene conditions, we argue that resilience features arising from metastable states might be crucial for the ES to follow sustainable trajectories in the Anthropocene that prevent it run into a much hotter potential equilibrium state.

Figures (2)

• Figure 1: A schematic illustration of the evolution of the Earth System with a start from the Neolithic revolution ( 12.000 years ago). Leading up to its current state (i.e. "warm Holocene Earth state") 7 of 9 planetary boundaries have been transgressed. A continuation on this pathway suggests that the Earth system may end up in a Hothouse Earth state (Steffen et al. 2018) (left pathway). However, explicit dissipation of energy, and policies and actions geared at building resilience of a metastable "Holocene-like Earth state" (see also Fig. 2) could provide an opportunity to build a trajectory toward a future "cooling Earth state" (right pathway).
• Figure 2: Free energy in function of the temperature, planetary boundaries $(H)$ and resilience features (matastable state).