Regional Integrated Assessment Model
Integrated assessment models (IAMs) are one of the key tools for examining the interactions between biophysical responses of the Earth system to climate change and the associated economic responses of human systems. This project seeks to apply a regional IAM framework to the Gulf Coast region of the United States—a region where climate impacts and adaptation, agriculture and land use issues, coastal issues, and energy supply issues are all occurring simultaneously, but for which integrated modeling has not been seriously attempted.
The selected IAM framework is based upon the Global Change Assessment Model (GCAM), developed by Pacific Northwest National Laboratory (PNNL), which is being regionalized to develop a new regional IAM capability (Regional Global Change Assessment Model [RCGAM]). RCGAM will use the newly developed representative concentration pathways (RCPs) to drive global climate simulations with the Community Climate System Model (CCSM). Regional climate scenarios for the Gulf Coast will be developed by downscaling CCSM results using the Weather Research and Forecasting regional climate model coupled to the Regional Ocean Model Systemocean model. Additional modeling of the coastal zone, including the effects of sea-level rise and storms on coastal inundation, will be undertaken with the Finite Volume Community Ocean Model coastal ocean circulation model. This biophysical information will be applied in impacts models coupled with RGCAM to assess climate change impacts at the land-water-energy nexus. A range of mitigation and adaptation experiments subsequently will be applied to RGCAM to test the costs, benefits, and trade-offs associated with different policy options for addressing the risks of climate change.
In developing and applying RGCAM for the Gulf Coast region, there are four key research questions for which it is hoped new insights will be gained:
1) What are the regional characteristics and opportunities for mitigation and adaptation strategies? For example, are there physical or economic constraints that make the implementation of different energy technologies or mitigation strategies more difficult, but that are only appreciated when simulations are done with greater regional specificity than the national or international strategies that are done today?
2) How do changes in mean climate and climate variability affect adaptation and mitigation strategies?
3) What are the interactions between management decisions and natural processes that contribute to rapid, or nonlinear changes in the environment? Where are such nonlinarities, and how do their consequences contribute to climate feedbacks?
4) How will adaptation and mitigation strategies interact in the next few decades?
While IAMs have been in development and use for a number of years, such models have largely targeted large aggregate geographic regions, and thus, regionalized approaches to such modeling are largely unexplored. Yet, increasingly, decision-makers seek insights regarding the implications of climate change and policy responses at more refined scales. Therein lies the utility of developing IAMs for regional applications. In developing such approaches, one of the main objectives is to understand the implications of such integrated modeling at regional scales and how the insights that such models might provide differ from insights derived from models at coarser scales with national or international domains.