A Tool for Exploring State-Level Changes Across Multiple Systems
GCAM-USA is a modified version of the Global Change Analysis Model (GCAM), which incorporates state-level detail of multiple sectors in the United States (U.S.). It is an integrated model that captures interactions between the economic, energy, water, and land systems in a globally consistent framework. Researchers recently introduced several key improvements to GCAM-USA, which now includes data pertaining to water supplies and demands as well as an improved representation of electric power plant operations. GCAM-USA can be used to explore how changes in population, economic growth, technology, or policy affect the production of and demand for energy, water, and crops at the U.S. state level while maintaining consistency with broader global conditions.
Models like GCAM-USA capture important interactions between regions, sectors, human systems, and the Earth system to explore how they may evolve in the future. Similar models often operate at coarse spatial and temporal scales, dividing the world into at most three dozen regions and running in half-decade time periods. GCAM-USA offers more spatial (dividing the U.S. into 50 states and D.C.) and temporal/process detail (power plant operations by day and night for each month) than comparable models. This helps capture important regional dynamics that affect these systems while maintaining consistency with international conditions.
A recent paper provides a detailed description of GCAM-USA’s capabilities, with an emphasis on several recent model improvements. GCAM-USA represents the U.S. economic and energy systems for all 50 states and D.C. It includes state-level data pertaining to water demands (multiple scales), water supplies (river basin level), and agriculture and land-use decisions (river basin level). The latest version of GCAM-USA includes a new electric power module that separates multi-decadal decisions about power plant investments from the plant operational decisions needed to meet electricity demands during the day and night each month.
The paper outlines key assumptions and future trends embedded in GCAM-USA’s default reference scenario. Applying the model generated four illustrative scenarios varying across two dimensions: population and economic growth (default vs. high growth) and energy system evolution (current trends vs. a long-term transition toward low-carbon technologies). The work presents results including total energy supply; electrification of end-use sectors (e.g., buildings, industry, transportation); power sector capacity, generation, and technology utilization; water withdrawals by state and sector; water supply by source; and changes in land allocation at multiple scales to demonstrate GCAM-USA’s broad capabilities.