A leading climatologist urged government space research organizations to jointly fund a five-satellite constellation in geostationary orbit to monitor emissions of carbon dioxide and methane on behalf of a future international treaty to limit global warming.

Berrien Moore, who is one of the authors of the report issued by the International Panel on Climate Change (IPCC), said no major government will agree to limit its greenhouse-gas emissions unless it can be assured that other nations are doing likewise.

“A [geostationary Earth orbiting] constellation gives you constant staring and a way of verifying that everyone is respecting the rules,” Moore said July 19.

Addressing the Cospar congress, Moore urged government officials to strip away the complexity of climate-change monitoring to its core requirement of reducing emissions of carbon dioxide and methane. “These are the two gases that will be subject to treaties that will need verification,” he said.

Moore, who recently became dean of the college of atmospheric and geographic sciences at the University of Oklahoma, also urged NASA to redesign the second model of the Ocean Carbon Observatory (OCO) satellite to replace the original model that was lost in 2009 during a launch failure.

OCO-2, which will be nearly identical to the original OCO, will have only a 10-kilometer swath width, making it “very difficult to use as a treaty verification system.”

In an interview, Moore agreed it may be too late to change the design of OCO-2. Orbital Sciences Corp. already has begun work on OCO-2, and NASA in June announced it awarded the Dulles, Va.-based company a contract to launch the satellite in early 2013 (see related story, page 6).

Taking emissions measurements precise enough to serve as treaty-verification platforms from geostationary orbit 36,000 kilometers above the equator will stretch today’s available technology but does not represent a radical leap into the future, according to Robert Laine, chief technology officer for Astrium Satellites, one of Europe’s principal satellite prime contractors.

OHB Technology of Germany is trying to assemble a consortium to work the problem from low Earth orbit with a satellite called CarbonSat, which would have a swath width of 500 kilometers. Five CarbonSat satellites could provide daily CO2 and methane measurements worldwide. The CarbonSat development model would appear to borrow from the Disaster Monitoring Constellation now in orbit, in which each national contributor finances its own satellite.

Peter B. de Selding was the Paris bureau chief for SpaceNews.