Peter Hess works to make sure climate models take atmospheric chemistry into account.
As climate models grow more sophisticated, they are increasingly incorporating the effects of chemistry, says Hess, such as the effects of nitrogen. “In natural systems, nitrogen acts a plant fertilizer, so it affects the biosphere which in turn takes up more carbon from the atmosphere,” he says.
Sulfate aerosols, a component of air pollution, are another example of how atmospheric chemistry affects climate. Sulfate particles in the atmosphere reflect some of the sun’s heat, partially offsetting the carbon dioxide-driven greenhouse effect. “The observed surface temperature increase has been such that, up to now, it seems sulfates have counteracted some of the potential warming,” says Hess. “But sulfates are well controlled now here in the West, and the idea is that as China starts to control sulfate emissions, that effect will go away.”
Before joining Cornell as an associate professor without tenure, Hess worked for 15 years at the National Center for Atmospheric Research in Boulder, Colorado. His work there was referenced in reports by the Intergovernmental Panel on Climate Change, which shared the 2007 Nobel Peace Prize with former Vice President Al Gore. “Creating models like the Community Climate System Model used in the IPCC report is a huge group effort,” he says. “It’s really the joint effort of many, many, many people.”
Cornell has become a family affair for Hess, who graduated from the university in 1979 with a B.A. in physics. Not only is his father George a professor here (in biochemistry and molecular and cell biology), but his wife Natalie Mahowald is a new faculty member in Earth and Atmospheric Sciences. The two met at NCAR.
Hess and Mahowald live in Cayuga Heights. They usually walk to work and have a hybrid electric vehicle for longer trips. But Hess knows that just one or two flights per year to academic conferences can wipe out all his efforts at reducing his carbon footprint. “The other ironic thing,” he says, “is that to run these models takes a huge amount of energy to cool the computers. In fact, the facility I use is moving to Wyoming to be closer to energy supplies.”
Alternative energy sources might help, but before large public investment, their full impact on climate must be understood. A couple of research areas Hess has delved into since coming to Cornell aim to do just that. “I’m looking at the impact on climate and atmospheric chemistry of growing and burning biofuels,” he says. “And the impact of ground-level ozone on plants. Plants exposed to ozone don’t grow as much, impacting the carbon cycle.”
The chance to explore such new areas is part of what drew Hess to Cornell. “I was ready for a change and I like the university environment,” he says. “It tends to be a little more intellectually stimulating than a research institution.”
Prof. Hess' Web site
