Influence of El Niño on atmospheric CO 2 over the tropical Pacific Ocean: Findings from NASA's OCO-2 mission

Spaceborne observations of carbon dioxide (CO ) from the Orbiting Carbon Observatory-2 are used to characterize the response of tropical atmospheric CO concentrations to the strong El Niño event of 2015-2016. Although correlations between the growth rate of atmospheric CO concentrations and the El Niño-Southern Oscillation are well known, the magnitude of the correlation and the timing of the responses of oceanic and terrestrial carbon cycle remain poorly constrained in space and time. We used space-based CO observations to confirm that the tropical Pacific Ocean does play an early and important role in modulating the changes in atmospheric CO concentrations during El Niño events-a phenomenon inferred but not previously observed because of insufficient high-density, broad-scale CO observations over the tropics.