The Science

Future energy and land-use patterns are important factors in Earth system models, but the standard approach is to feed these into the factors in the Earth system without permitting the Earth system to in turn affect the energy and land-use. Researchers identified and measured inconsistencies associated with this approach. They found that inconsistencies can be eliminated by creating feedback loops. By passing data between human and Earth system models, the impacts of Earth system change influence the energy-economic systems. For example, higher carbon dioxide levels led to higher crop yields, lower crop prices, and less conversion of forest to cropland.

The Impact

The research described a vital source of uncertainty in most global-scale models. The study showed that a fully coupled human-Earth system model eliminates this uncertainty and improves constraints on future Earth system projections. These projections are useful to energy system analysis.


Through this research, scientists learned that synchronous two-way coupling of an Earth system model with an energy-economics model can eliminate important sources of Earth and human system projection uncertainty. The research identified and quantified inconsistencies associated with asynchronous, one-way coupling of human and Earth system models, and eliminated those inconsistencies by designing and implementing a synchronous two-way coupled model of human and Earth system processes. By passing information on biospheric processes from the Earth system model to the human system model, impacts of climate and Earth system changes were allowed to influence the energy-economic systems. Higher carbon dioxide concentrations led to increased vegetation productivity, higher crop yields (including biomass energy crops), lower crop prices, and reduced conversion of forest to cropland. Feedbacks in the energy system led to reduced energy consumption and fossil fuel emissions, and feedbacks in the Earth system led to increased land carbon storage. The research suggests that significant uncertainty reduction in the area of future climate projection could be achieved by adopting two-way coupling between Earth systems and human systems as a standard practice for multi-model analyses.


The U.S. Department of Energy, Office of Science, Biological and Environmental Research supported this work as part of the Improving the Representations of Human-Earth System Interactions and Accelerated Climate Modeling for Energy (ACME) projects of the Earth System Modeling (ESM) program.


P. Thornton, K. Calvin, A. Jones, A. Di Vittorio, B. Bond-Lamberty, L. Chini, X. Shi, J. Mao, W.D. Collins, J. Edmonds, A. Thomson, J. Truesdale, A. Craig, M.L. Branstetter, and G. Hurtt, "Biospheric feedback effects in a synchronously coupled model of human and Earth systems." Nature Climate Change 7, 496-500 (2017). [DOI: 10.1038/nclimate3310]

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Journal Link: Nature Climate Change 7, 496-500 (2017). [DOI: 10.1038/nclimate3310]