A prototype Earth system impact metric from cross-scale Earth system interactions

The planetary boundary framework sets limits on the human pressures that maintain the Earth system in a Holocene-like state that supports human wellbeing. A sub-global assessment of these interactions between these pressures is needed to enable businesses and other actors to assess the systemic environmental impacts of their decisions. Here, we analysed interactions between important boundaries for climate change, surface water runoff, and vegetation cover using the dynamic vegetation model LPJmL. Using a feedback model, we then studied how these interactions amplify environmental impacts. For example, we showed that interactions more than triple the Earth system impact of deforestation in South American tropical forest. Finally, we created a prototype Earth system impact metric by combining these amplification factors with an assessment of the current state of the Earth system. We envision that future versions of our prototype metric will allow businesses and other actors to better assess environmental impacts of their decisions.