The Scientific and Societal Importance of the Orbiting Carbon Observatories

In July 2014, under foggy skies, the second Orbiting Carbon Observatory (OCO-2) satellite successfully lifted off from Vandenberg Air Force in California into low earth orbit, following the failed launch of the original OCO satellite in 2009.  It was followed by the installation of it’s near twin, OCO-3, on the International Space Station in 2019.  Together, OCO-2 and OCO-3 measure and monitor two primary aspects of the earth’s carbon cycle, the column-mean concentration of carbon dioxide (XCO₂), and Solar-Induced chlorophyll Fluorescence from terrestrial plants (SIF).  The OCOs make these measurements with their high-spectral resolution near-infrared spectrometers, which measure the spectra of reflected sunlight in three spectral bands centered on 765 nm, 1610 nm, and 2060 nm wavelength.  OCO-2 and OCO-3 are funded and managed by NASA, and have been making measurements for over 11 and 6 years, respectively. Further, both instruments are healthy and should be able to continue observations for many years to come.

In this presentation, I will discuss the importance of these measurements, from both a scientific and societal point of view.  NASA’s space-based measurements of XCO2 and SIF have led to a much-improved understanding of carbon uptake by the land biosphere, a key service by the earth to limit the growth rate of atmospheric CO₂.  They have led us to be able to better predict agricultural-relevant quantities such as crop yields and flash droughts.  We have quantified mean biospheric uptake of CO₂ from dozens of the larger nation-states on earth, helping to better quantify their total carbon emissions.  Crucially, this success has led to a large international effort to build next-generation satellite instruments based on the same technology, but with significantly enhanced capabilities related to spatial sampling and coverage.   Continuing to operate these uniquely-capable satellite instruments will enable us to continue measuring and monitoring critical aspects of the earth’s carbon cycle for years into the future, bridging the gap until the next-gen instruments come online.