New approaches to quantifying global ecosystems including dynamical human interactions

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Global ecosystems are being transformed at rates that probably have not occurred since the end of the Cretaceous, as a result of human activities. Attempts to understand this transformation are being undertaken by many thousands of researchers, yielding a great wealth of detailed knowledge. But these efforts are often isolated within disciplines, so that the full interacting system - including human activity - is rarely studied within a common quantitative framework. This conceptual fragmentation leaves important gaps in the understanding of how entire ecosystems function within the physical environment of the Earth surface, and ignores the valuable information that observations of humans can potentially shed on ecosystem functioning. My research program builds on my background in modeling climate, biogeochemistry and ecosystems, and is now oriented towards a better understanding of the human-ecosystem interface by developing an integrated, quantitative framework that resolves the global ecosystem including its human component. The approach is built on recent advances in macroecology, that provide a novel means to predict whole terrestrial and marine ecosystems from environmental features with relatively few equations, based on body size and principles of energy flow. These ecosystem models will be coupled to simple representations of human activities, suitable for centennial-timescale integrations and tailored to maximize the use of available data constraints. The general goals are to provide a more holistic understanding of ecosystems, including humans, while shedding new light on the functioning of biological systems by leveraging global observations of human activity. This proposal takes a major step forward through four workpackages. First, the development of a global two-dimensional Surface Earth System Model - the first of its kind - will allow terrestrial and marine ecosystems to be fully integrated with human populations in a computationally-efficient design. Second, a major expansion and refinement of our prior size-based marine ecosystem model, will improve realism and connect ecosystem processes with biogeochemical cycling. Third, construction of new size-based ecosystem approaches for the land surface, tailored to use the large global datasets available for model calibration, and to provide the standard basis for the grid-based ecological components. Fourth, a dynamic, interactive, generalized model of human populations and their activities, which can be applied to simulate the large-scale features of biomass extraction by humans, the ecosystem impacts, and how they changed over human prehistory and history. These four workpackages will achieve critical technical advances, paving the way for further steps in the research program, while contributing to hypothesis development and refinement that are likely to produce unexpected discoveries in the short term.