Science Needs for a Terrestrial Biosphere Tipping Point Early Warning System

Abstract

Abstract

Abstract Tipping points in the Earth system have the potential to cause major detrimental impacts to the biosphere and societies. Their inherent nonlinearity implies that even relatively small additional increases in external forcing might result in disproportionately large adjustments to components of the Earth system. In some cases, tipping points may lead to alternative states that would be difficult to return from. Here, we discuss ways to maximize the usefulness of Earth Observation (EO) data to improve Early Warning Systems of tipping points in the terrestrial biosphere. We focus on the terrestrial biosphere because it provides critical ecosystem services, offers more tractable dynamics for early warning development, and is exceptionally amenable to remote sensing across multiple spatial scales. We synthesize two key elements: potential tipping elements and dynamics in the terrestrial biosphere, and corresponding mathematical theory and methods that can determine resilience levels. With such combined knowledge, we discuss the feasibility of generating warnings of approaching tipping points, filtered through consideration of what can be remotely sensed. EO data is generally of short length in time but has extensive spatial coverage at fine resolution, leading to emphasis on spatial‐temporal resilience sensing and building early warning indicators that may incorporate parallel data on system forcing. We describe how “space‐for‐time” substitutions may capitalize on EO's strong areal coverage to understand whether ecosystems might be nearer to tipping depending on location, enabling more complete assessment of emerging signals on the approach to strong nonlinearities.