CARBON CALCULATOR: The $280 million Orbiting Carbon Observatory, which crashed on launch last year, would collect precise measurements of CO2 output from individual cities and power plants around the world. Image: NASA
Even if world leaders sign a new climate treaty and begin cutting greenhouse gas emissions, it could be years before their progress can be independently verified, says a new National Academy of Sciences report.
Current U.N. rules require countries to submit national emissions inventories, but the data are self-reported, not required regularly from all countries, and there are no independent data to verify it.
Developing the capacity to cross-check those self-reported numbers is at least five years off, according to the NAS analysis released Friday.
That it appears to be possible at all was a pleasant surprise for Stephen Pacala, the Princeton University climate researcher who led the study.
"I went into the effort reluctantly, because I was convinced that we probably couldn't do the job," he said. "That it was not possible to independently verify self-reported estimates by countries unless you had something like on-the-ground inspectors that were off the table."
But what Pacala and his colleagues found was that the technology needed to develop that capability is available now.
Deploying those tools will accelerate a change in viewpoint for scientists who track carbon dioxide and other greenhouse gases. The current global network of ground stations, observatories, aircraft and other instruments emerged during a period when scientists were trying to answer questions about the total amount of CO2 in the atmosphere and how natural sources and sinks contributed to the overall total (ClimateWire, Dec. 14, 2009).
Tools are there, but some are misplaced
That meant situating measuring at sites far away from population centers, where power plants, automobiles and other fossil fuel-powered infrastructure would skew efforts to measure a global average level of CO2, methane and other heat-trapping gases.
"We had focused for years on the much more difficult problem of finding the missing carbon sink," Pacala said. "So for the U.S. to try to estimate emissions from China, or vice versa -- the current technology is terrible. We can't tell if another country is a source or a sink right now."
Today, scientists' aims are shifting as governments debate strict reductions in their CO2 output to stave off severe climate change.
The science academy's president, atmospheric chemist Ralph Cicerone, took the unusual step of initiating the study without a request from Congress, Pacala said, because there was little information about the world's ability to monitor greenhouse gas emissions produced by human activities at the level of detail required to verify compliance with a climate treaty.
"He recognized that we really couldn't say what it would mean to monitor and verify a greenhouse gas treaty," Pacala said. "As one moves towards a treaty with real teeth and bite in it, the need to monitor and verify goes up. It was clear that we didn't know enough about that."
That doesn't mean the current self-reporting system isn't useful, the NAS report notes. In many developed countries, like the United States, the CO2 emissions estimates developed this way carry an uncertainty of 5 percent or less.
But for CO2 estimates from developing countries, and measurements of greenhouse gases aside from CO2, the uncertainty can be much greater.
Copy of failed NASA satellite needed in short term
To upgrade global monitoring of greenhouse gas emissions, the report recommends that the United Nations require developing nations to report their output every year, as developed countries already do. Helping the 10 largest emitters -- a list of nations that includes China, Indonesia and India -- do so would cost about $11 million over five years.