Mapping Earth's CO₂

After months of delays, a satellite designed to help generate the first detailed, time-resolved global maps of carbon dioxide sources and sinks is slated for launch on Feb. 23.

The daily detailed measurements from NASA's Orbiting Carbon Observatory (OCO) will give vastly more information than the sparse CO₂-monitoring stations that now dot Earth. By knowing where and when CO₂ is being emitted and taken up, scientists may be able to understand how the gas influences climate change and, in particular, global warming.

The orbiting observatory is "a huge stepping stone toward answering these questions," said Anna M. Michalak, OCO scientist and engineering and atmospheric sciences professor at the University of Michigan, at a press conference at NASA headquarters on Jan. 29.

Previously set to launch last fall, OCO was postponed after a series of technical problems. The craft carries near-infrared absorption spectrometers designed to monitor, in high resolution, concentrations of CO₂ from Earth's surface to the top of its atmosphere.

Humans produce, via fossil fuel and biomass burning, about 2% of the 300 billion tons of CO₂ emitted into the atmosphere each year. About 50% of this human-generated CO₂ remains in the atmosphere, and 30% is taken up by the ocean, but the global distribution of the remaining CO₂, presumed to be taken up by plants and soil, is unknown.

Data from the satellite are "going to be very useful for understanding the carbon cycle," says Atul Jain, an atmospheric sciences professor at the University of Illinois, Urbana-Champaign, who develops computer models of carbon cycling. "We don't understand where the sources and sinks are.