GHG Database Not Big Enough to Measure Progress

• May 08, 2008

Monitoring Earth's rising greenhouse gas levels will require a global data collection network 10 times larger than the one currently in place in order to quantify regional progress in emission reductions, according to a new research commentary by University of Colorado and National Oceanic and Atmospheric Administration researchers.

CU-Boulder Research Associate Melinda Marquis and NOAA scientist Pieter Tans, said with atmospheric carbon dioxide (CO₂) concentrations now at 385 parts per million and rising, the need for improved regional greenhouse gas measurements is critical. Their comments appear in the April 25 issue of Science. While the current observation network can measure CO₂ fluxes on a continental scale, charting regional emissions where significant mitigation efforts are under way -- like California, New England, and European countries -- requires a more densely populated network, they said.

"The question is whether scientists in the United States and around the world have what they need to monitor regional fluxes in atmospheric carbon dioxide," said Marquis, a scientist at the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and NOAA. "Right now, they don't."

While CO₂ levels are climbing by 2 parts per million annually -- a rate expected to increase as China and India continue to industrialize -- effective regional CO₂ monitoring strategies are virtually nonexistent, she said. Scientists are limited in their ability to distinguish between distant and nearby carbon sources and "sinks," or storage areas, for example, by the accuracy of atmospheric transport models that reflect details of terrain, winds, and the mixing of gases near observation sites.

"We are in uncharted territory as far as knowing how safe these high CO₂ levels are for the Earth," she said. "Instead of tackling a very complex challenge with the equivalent of Magellan's maps, we need to use the equivalent of Google Earth."

Marquis and Tans propose increasing the number of global carbon measurement sites from about 100 to 1,000, which would decrease the uncertainty in computer models and help scientists better quantify changes. "With existing tools, we could gather large amounts of additional CO₂ data for a relatively small investment," said Marquis. "The next step is to muster the political will to fund these efforts."

Scientists currently sample CO₂ using air flasks, in-situ measurements from transmitter towers up to 2,000 feet high and via aircraft sensors. The authors proposed putting additional CO₂ sensors on existing and new transmitter towers that can gather large volumes of climate data. While Europe and the United States have small networks of tall transmitter towers equipped with CO₂ instruments, such towers are rare on the rest of the planet, she said.

Satellites queued for launch in the next few years to help monitor atmospheric CO₂ levels include the Orbiting Carbon Observatory and the Greenhouse Gases Observing Satellite, said Marquis. The satellites will augment ground-based and aircraft measurements charting terrestrial photosynthesis, carbon sinks, CO₂ respiration sources, ocean-atmosphere gas exchanges and CO₂ emissions from wildfires.