Exploring dynamics in global human-Earth system influences, responses, and feedbacks

Interactions between human and natural systems are at the heart of many economic, environmental, and national security issues facing the United States and the world today. Understanding and accounting for these interactions poses challenges because human and natural systems evolve over time in response to a wide range of short- and long-term influences. Understanding these complex dynamics requires innovative tools that can represent not only the fundamental drivers of change and responses of individual systems, but also how different systems interact and co-evolve.

The goal of the Global Change Intersectoral Modeling System (GCIMS) scientific focus area is improving the understanding of the complex interactions among energy, water, land, climate, socioeconomics, and other important human and natural systems at regional to global and seasonal to centennial scales. GCIMS has an emphasis on developing and applying an internally consistent, open-source, and computationally efficient modeling framework that captures the evolution of the integrated human–Earth system. The GCIMS team seeks to simultaneously resolve the effects of:

  • compounding short- and long-term influences on energy, water, land, climate, and socioeconomic systems over the next 10–100 years;
  • the responses of these systems to those influences; and
  • previously unresolved feedbacks that fundamentally alter the frequency or intensity of influences.


The GCIMS focus has evolved. In its early days, GCIMS focused on a limited number of highly aggregated systems. Today, the team considers multiple interactions (energy-water-land-economy-climate) at greater temporal, spatial, and process resolution (regional-national-global and seasonal to centennial). The research team focuses on the following central science questions for this current research phase:

  1. How will compounding human and environmental influences affect the coevolution of energy, water, land, climate, and socioeconomic systems? And what individual and combination of influences lead to compounding effects within the U.S. and globally?
  2. How will regional teleconnections via resource supply networks and trade create, amplify, or attenuate the responses associated with different influences in the U.S. and other parts of the world, and how will varying assumptions about the ease or difficulty of trade alter these teleconnections?
  3. How will human responses to short-term influences through investments in long-lived capacity and in storage technologies in the energy, water, and land systems affect the long-term dynamics of these systems? How will these investments affect the ability to respond to future influences in the U.S. and globally?
  4. How could the response of the human–Earth system to influences create feedbacks that are currently not captured in integrated modeling frameworks, and which feedbacks will result in substantial changes in the evolution of human and Earth systems?


The GCIMS project develops and uses the Global Change Analysis Model (GCAM) along with a suite of dedicated, open-source systems models that include Demeter (global land-use downscaling), Hector (climate emulator), Xanthos (global hydrology), fldgen (climate variability emulator), and Tethys (global water demand downscaling). Notably, GCAM is recognized as a leading human-Earth systems model since its inception more than three decades ago. 

With a large domestic and international user base and model training program, GCAM has made critical contributions to the understanding of how energy technology, the integrated water cycle, land-use change, and other human activities influence Earth system dynamics. It has also been the foundation for developing future scenarios that are used in science-based environmental and energy research. Over the years, the complexity of GCAM has evolved commensurate with scientific questions about how human and earth systems interact.

At its core, GCAM is an economic model with detailed physical system representations of energy, water, land, biogeochemistry, and climate components. GCAM is also used to represent the human component of the U.S. Department of Energy’s Energy Exascale Earth System Model (E3SM).


GCIMS research is positioned to lead to scientific advances by improving the integrated understanding of influences, responses, and feedbacks in the coupled human-Earth system. A key focus is understanding how human and Earth systems interact with one another globally and regionally in response to short- and long-term influences, and the implications of these responses and feedbacks for the co-evolution of energy, water, land, socioeconomic, and climate systems.


GCIMS is funded by the U.S. Department of Energy’s Office of Science as part of the MultiSector Dynamics program area within the Earth and Environmental Systems Modeling program.