Colorado State University Professor to Speak Dec. 16 at American Geophysical Union Science Writers Workshop

Colorado State University Professor Scott Denning will speak with reporters and science writers in San Francisco on Tuesday, Dec. 16, about the global carbon cycle and how it relates to NASA’s next Earth science mission, called the Orbiting Carbon Observatory.

Denning, an atmospheric scientist and expert in climate change, will speak at noon MST at the fall meeting of the American Geophysical Union Press Conference Room (Room 3015) of the Moscone Center. He’ll conduct the workshop with David Crisp, the principal investigator for the mission at NASA’s Jet Propulsion Laboratory.

NASA’s Orbiting Carbon Observatory, which is scheduled for launch in 2009, is intended to track small changes in the amount of atmospheric carbon dioxide and locate sources, such as fossil fuels, and "sinks" by observing where and when the amount of CO2 changes as the air passes over cities, forests, oceans and farms.

A team of atmospheric scientists led by Denis O’Brien at Colorado State University have developed the computer program that will convert the spectroscopic measurements captured by the Orbiting Carbon Observatory to atmospheric CO2 data. Denning’s group will analyze their estimates and account for winds and clouds to produce time-varying maps of sources, such as fossil fuels, and sinks of CO2, to help understand the processes and mechanisms involved.

"We hope this mission will lead to much better prediction models for climate, oceanography and ecology," Denning said.

Atmospheric CO2, which has been increasing rapidly due to the combustion of fossil fuels like coal, oil and natural gas, is a cause for concern because it is likely to cause global climate change, Denning said. But only about half of the CO2 released from fossil fuel stays in the atmosphere – the rest has been dissolving into the oceans and incorporated into land plants and soils known as "sink," which helps to remove about half of the world’s industrial greenhouse emissions.

The oceans can only absorb a certain amount of CO2 because warm ocean water on top prevents it from being absorbed by colder, denser water. Plants on land convert CO2 to wood, leaves and roots during photosynthesis, but the carbon comes right back out as CO2 when the plants die and decay.

"The fact that land plants currently take up nearly 25 percent of the world’s fossil fuel emissions means that, at the planetary scale, plants are growing faster than they are dying, which is quite remarkable," Denning said. "This apparently reflects such land-use change as forest fire suppression and abandonment of farms to woodlots in the developed world and changes in nutrient cycles worldwide. Many scientists expect these carbon sinks to saturate and stop taking up carbon in the coming years."

The orbiting observatory will measure the spectrum of reflected sunlight from 700 kilometers up, using absorption lines in these spectra to estimate the total amount of CO2 under the spacecraft. It also will help scientists quantitatively account for where the sinks operate, precisely how they work, or whether they will continue to operate in the future. If the sinks were to saturate – or even slow down substantially – atmospheric CO2 would increase a lot more quickly, Denning said.

Colorado State University’s College of Engineering and the Cooperative Institute for Research in the Atmosphere, or CIRA, have worked with NASA on other Earth science missions. CSU scientist Graeme Stephens conceived of CloudSat, the world’s first cloud-profiling radar in orbit, which NASA’s Jet Propulsion Laboratory launched on April 28, 2006. CIRA scientists are collecting CloudSat’s data and distributing it to the scientific community worldwide.