ucar Highlights 2007

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Winds of Change


Understanding the most critical environmental threat of our time—a climate in flux—is one of the prime goals of NCAR scientists and their university colleagues. Their work flows from NCAR’s rich and sustained program of basic research on the Earth system.

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The character of change | Top of the world | Shaping the atmosphere | Models and molecules |

How to talk about climate change | Oceans and carbon dioxide | A tropical tempest

 
HIGHLIGHTS Multimedia

web iconDon Wuebbles (University of Illinois at Urbana-Champaign)

 

Models and molecules: Interactive chemistry comes of age

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Don Wuebbles

Analyzing which chemicals matter most to climate—and how much difference each one makes—is the forte of Donald Wuebbles. Director of the University of Illinois’ School of Earth, Society and Environment, Wuebbles is also part of the team working to bring more realistic chemical interactions into the NCAR-based Community Climate System Model (CCSM).

At Lawrence Livermore National Laboratory in the 1980s, Wuebbles devised the concept of ozone depletion potentials. This index shows the relative power packed by each type of ozone-threatening molecule. Wuebbles helped transmute the concept into global warming potentials, a key tool for policymakers. The new index is based on the heat-absorbing ability and lifespan of each greenhouse gas. Methane is far more powerful than carbon dioxide, for example, but it stays in the atmosphere for much less time. (There’s also much less of it.)
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The chemistry-oriented version of the Community Climate System Model can track a variety of constituents and their interactions with the atmosphere.

“I’m intrigued, as are a lot of other people, in looking at how global change interacts with atmospheric chemistry and biogeochemical cycles,” says Wuebbles. He and colleagues at Livermore built a pioneering three-dimensional model of air chemistry in the early 1990s. “We were doing well, but when I came to Illinois I said, I’m not going to develop another model. These are expensive tools, and they take a lot of time.”

Instead, Wuebbles took advantage of NCAR’s community-based model development. He began working with NCAR lead Guy Brasseur on MOZART (Model for Ozone and Related Chemical Tracers). The model soon became a flagship tool for analyzing more than 100 airborne compounds. However, it wasn’t designed to show the two-way interaction between chemicals and climate change.

That’s now changing. In an effort led by NCAR’s Peter Hess, MOZART is now being incorporated into the CCSM in a fully interactive fashion. The upgraded model will depict salt, dust, soot, and a wide range of other particles and gases that influence cloud formation and radiation. Tests began in 2007 on this chemistry component of CCSM. “I think we’re going forth with a version that has all the right stuff,” says Wuebbles. “There could be some interesting surprises.”


The character of change | Top of the world | Shaping the atmosphere | Models and molecules |

How to talk about climate change | Oceans and carbon dioxide | A tropical tempest