PROJECT SUMMARY The objective of this project is to generate the first empirical estimate of the behavioral cost of carbon – the human health-related behavioral impacts imposed by incremental increases in greenhouse gas (GHG) emissions. The societal behavioral costs and benefits of climate stressors caused by GHG emissions remain unknown in the US and globally. This missing behavioral component of the social cost of carbon (SCC) may blind both climate and health policy responses to the true scope of consequences from climate change. This project will evaluate three hypothesized behavioral costs of carbon. This proposal aims to 1) estimate the first US domestic substance use cost of carbon by linking alcohol consumption observations and substance use panel data with high resolution meteorological data (i.e. weather and climate observations) across the US; 2) evaluate the US and global sleep cost of carbon by applying multi-stage multivariate time-series fixed effects models to estimate associations between local meteorological conditions and both self-reported and actigraphy-recorded sleep outcomes; 3) assess the preliminary physical activity cost of carbon and estimate local climate-behavioral impact projections – statistically accounting for acclimatization – for every county in the US and every region worldwide. In Aim 1, the US substance use cost of carbon will be derived from estimating climate – substance use response functions for daily household alcohol consumption measured by the nationally representative Nielsen-IQ Consumer Panel (NIQCP), self-reported individual substance use registered by the Behavioral Risk Factor Surveillance System (BRFSS), and zip code-level counts of all substance use disorder emergency department visits (HCUP SEDD) and hospitalizations (HCUP SID) in a dataset that includes 95% of US hospital discharges. In Aim 2, US and global estimates of the sleep cost of carbon will be derived from ambient temperature–sleep response estimates using nationally representative US time use survey data (ATUS) and globally extensive actigraphy data (GSSPAD). In Aim 3, nationally representative physical activity survey data (BRFSS) and two large-scale wrist actigraphy and smartphone-based accelerometry datasets from prior research will be linked with global reanalysis (ECMWF ERA5) meteorological data to estimate climate – physical activity response curves which are then coupled with climate model output produced by NASA Earth Exchange (NEX) to inform both the US and global physical activity cost of carbon. This independent research agenda will inform the world's first behavioral cost of carbon (BCC). The BCC will allow healthcare stakeholders and policymakers to anticipate and mitigate the future behavioral costs of societal emissions decisions. The proposed research directly responds to the NIH Strategic Plan's 2021-2025 “disease prevention and health promotion” objective, aligns with the crosscutting themes by “addressing public health challenges across the lifespan” and “promoting collaborative science,” while also building cutting-edge spatial data science capacity at the nexus of climate change and behavioral medicine.

PROJECT NARRATIVE The downstream behavioral impacts of carbon dioxide (CO2) emissions remain unknown in the US and globally, so they are not yet included in the US federal “social cost of carbon,” a metric used to quantify the human damages associated with a one-ton increase in greenhouse gas emissions. This proposed project evaluates the hypothesized behavioral costs of carbon for substance use, sleep outcomes, and physical activity. Characterizing how observed changes in climate, caused by each additional unit of greenhouse gas emissions today, impact future human health behaviors can have major implications for climate and health policies, which currently do not consider the behavioral costs of societies' emissions choices.