Understanding Trends and Drivers of CO2 based on OCO-2 and GOSAT satellite measurements over Texas, California, and Florida

As climate change intensifies, understanding the trends and drivers of greenhouse gases (GHGs) is vital to developing effective climate mitigation strategies and safeguarding human health. This study investigates carbon dioxide (CO₂) trends in the top three CO₂ emitting states (i.e., Texas, California, and Florida) in the United States by analyzing key influencing factors, including population changes, gross domestic product (GDP), energy consumption from nonrenewable and renewable sources, and the normalized vegetation difference index (NDVI). We assess the correlation of these factors with the column-averaged CO₂ (XCO₂) as measured by the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory-2 (OCO-2) satellite using the Pearson’s correlation method. Comparing data from these two satellites, which cover different periods (2010-2020 for GOSAT and 2015-2022 for OCO-2), provides a comprehensive understanding of XCO₂ trends in these states. In this study, we account for background XCO₂ concentrations and calculate the interannual changes of XCO₂ beyond these background levels to understand how anthropogenic activities in each state influence the rate of XCO₂ increase over the study periods. We analyze the variation of NDVI over time within each state, with a particular focus on its relationship with XCO₂ during summertime, when photosynthetic activity is at its peak. Each state exhibits unique patterns of energy consumption, including both nonrenewable energy (such as coal, natural gas, nuclear, and petroleum) and renewable energy (such as solar, wind, hydroelectricity, and biomass waste). As changes in the consumption of nonrenewable and renewable energy, driven by socioeconomic factors, vary from year to year, our correlation analysis of these key factors with XCO₂ in Texas, California, and Florida supports a better understanding of the annual trends and drivers of CO₂. The findings from this study can help state governments better prepare for and mitigate the impacts of climate change.