Changes in the Earth system affect the energy system; for example, rising temperatures lead to increased air conditioning usage. At the same time, changes in the energy system affect the Earth system; for example, increases in greenhouse gas emissions increase temperatures. Scientists typically quantify these effects separately through different mathematical models. This study quantifies both effects simultaneously and finds that considering the co-evolution of energy and climate results in higher temperatures than modeling the effects in isolation.
Understanding the feedbacks between the human and Earth systems is critical to understanding their future evolutions. This study demonstrates how to quantify these feedbacks in a single computationally efficient model. Using such a model allows researchers to examine the uncertainty in both climate and socioeconomics as well as how those uncertainties affect human-Earth system feedbacks. While the feedbacks between building energy demand and global mean temperature are modest, this study prompts future research on coupled human-Earth system feedbacks, particularly for land, water, and other types of energy infrastructure.
Human–Earth system modeling studies typically analyze feedbacks between the Earth and human systems by passing information between independent models. The reliance on existing Earth system model outputs limits both the ability to explore feedbacks under arbitrary scenarios and the ability to explore large-scale uncertainty in these interactions. This study explores a wide range of climate uncertainties and incorporates the implications of increased emissions from cooling. It employs a statistical relationship between global mean temperature change, produced by Hector, and heating and cooling degree days used in the Global Change Analysis Model. This produces changes in building energy demands at every time step and in every region. There is general agreement in the literature that increasing temperatures will increase cooling and decrease heating energy demands. However, there has not been a fully coupled analysis of this dynamic that would, for example, account for the feedback of increased cooling demands on hydrofluorocarbons. The spatial distribution of temperatures leads to substantial variation in cooling and heating energy change across regions, with the United States, India, and Sub-Saharan Africa experiencing a factor of two differences in cooling demand. While the feedbacks between building energy demand and global mean temperature are modest, this study prompts future research on coupled human-Earth system feedbacks, particularly for land, water, and other energy infrastructure.