UC Santa Cruz

Earth's carbon cycle controls the concentration of the greenhouse gas carbon dioxide (CO2) in the atmosphere, which influences the climate on our planet and thereby affects the many processes that control the carbon cycle. These climate-carbon cycle feedbacks determine the long-term Earth System response to biological evolution, geologic drivers, and events such as anthropogenic fossil fuel use. In Section “Earth's carbon cycle” of this chapter we outline the reservoirs and chemistry of carbon in Earth's surface environment; in Section “Carbon fluxes and dynamic balances” we describe the dynamics underpinning carbon cycle feedbacks, including a discussion of carbon cycle models, and in Section “Climate and the carbon cycle” we survey the observational evidence base for our current understanding of long-term Earth System change by focusing on available proxy records and reconstructions of the climate and carbon cycle across the Cenozoic Era. In facing our collective impacts on Earth's future carbon cycle and climate these concepts are fundamental to human stewardship of our environment.