Regional-Scale Earth System Models to Inform Land and Water Management Decisions: Limitations and Current Developments.

One of the grand challenges of the 21^st Century is to understand biogeochemical cycles in the biosphere, and in particular, to understand how to manage nitrogen (N) in the environment to maximize agricultural productivity while minimizing negative environmental effects.  Developing a clear understanding of climate and human-induced changes in environmental N cycling in tightly coupled atmospheric, terrestrial, and aquatic systems, including how these changes feed back into the climate system, is critical to addressing this challenge. In this presentation, we give an argument for why current Earth system models (EaSMs) may be limited in their ability to be useful for many agricultural and natural resource management decisions, and we provide an overview on the current development of EaSMs to address these shortcomings. We provide an example of one such model currently in development for the Pacific Northwest region of the US. The overarching goal in developing this model, the Biosphere-relevant Earth system model (BioEarth), is to improve our understanding of the interactions among C, N, and H₂O at the regional scale in the context of global change to inform decision makers’ strategies regarding natural and agricultural resource management.  The approach is to create a regional modeling framework by integrating a network of state-of-the-art process-based models that are currently in existence and that are undergoing continuous development. The rationale is that by choosing among the most sophisticated models for each Earth system component, and either linking these models (or fully integrating them where possible), the integrated modeling framework can be continually improved as each contributory component develops. The framework includes atmospheric models (for meteorology and atmospheric chemistry), land surface models (for hydrology, cropping systems, and biogeochemical cycling), aquatic models (for reservoir operations and nutrient export in rivers), and economic models. The end product will be a state-of-science regional Earth system modeling framework that explicitly addresses N and C flows in the context of inter-annual and decadal climate variability. Relevance and utility to decision-makers will be enhanced through integrated stakeholder input throughout model development. Communications research will be used to assess and improve the relevance of the new model for land management decision making.