Large and seasonally varying biospheric CO <sub>2</sub> fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon
J. B. Miller, Scott J. Lehman, K. R. Verhulst, Charles E. Miller, Riley Duren, Vineet Yadav, Sally Newman, C. Sloop
Abstract
Significance Megacities contribute significantly to national and global CO 2 emissions and are an increasingly important element of emissions mitigation efforts. Atmospheric monitoring helps to characterize urban emissions, but CO 2 measurements alone cannot distinguish between biogenic and fossil fuel contributions to observed CO 2 enhancements. We use measurements of CO 2 and the fossil fuel tracer 14 CO 2 to demonstrate that even for highly urbanized and arid environments such as Los Angeles, the managed urban biosphere contributes significantly to the local carbon budget. These findings highlight the need to understand and quantify urban biospheric CO 2 in order to more accurately measure and track fossil fuel–CO 2 emissions and the impact of urban greening campaigns, as needed to evaluate and optimize emissions mitigation strategies.