NASA’s Orbiting Carbon Observatory 2 (OCO-2) satellite, launched in 2014, measures atmospheric carbon dioxide levels with a spatial resolution of 3 km2. Data from the satellite will help scientists understand the global carbon cycle—and how that cycle may change in response to global warming. A set of five papers in Science analyzes OCO-2 data collected from 2014 to 2016, identifying seasonal effects on the carbon cycle as well as the influence of the 2015–16 El Niño weather event.
In one study, a team led by Junjie Liu of NASA’s Jet Propulsion Laboratory determined that tropical regions all released more carbon to the atmosphere during the El Niño event than average and that the releases had different origins—biomass burning in Asia, lower precipitation in South America, and higher temperatures in Africa (Science 2017, DOI: 10.1126/science.aam5690). These results, combined with expected precipitation and temperature changes in response to global warming, suggest that tropical lands may be a source rather than a sink of carbon in the future.
Another study looked at whether scientists may quantify plant biomass production by measuring solar-induced chlorophyll fluorescence via satellite, as suggested by previous research. Researchers led by Ying Sun of Cornell University and Christian Frankenberg of Caltech validated the space-based approach by comparing OCO-2 fluorescence measurements with ground and airborne data (Science 2017, DOI: 10.1126/science.aam5747).