...
Climate changes have important implications for regional and global energy system, land use, agriculture, water, human health, and settlement. These systems, in turn, have important implications for climate change. Many of the existing climate change projections use emissions scenarios developed by assuming that feedbacks from a changing climate will not influence emissions. Thus, these scenarios potentially miss important feedbacks between humans and Earth systems. To assess these feedbacks and to better understand how climate change and human systems interact, we have developed a new scientific tool, the integrated Earth system Model (iEAM). The iESM is based on coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling infrastructure. Three experiments were designed to introduce the development steps: 1) Experiment 0: Coupling land use and land cover information from GCAM to CESM, 2) Experiment 1: Additional coupling of climate change effects on ecosystem productivity from CESM to GCAM, producing a two-way coupling (or feedback loop), 3) Experiment 2: Additional coupling of energy and industrial CO2 emissions from GCAM to CESM, and completing a second feedback loop. Each development step was designed to answer different science question. Our results show that terrestrial systems interact strongly with human systems, and the nature of those interactions can have a significant impact on climate change on decadal scale. This two-way coupled Earth system model evolves differently from others that ignore feedbacks from the climate to human system, which can be used for the future climate change projects.Im