Global Climate Change Creates Tangled Web Of Interactions

February 17, 1998

Philadelphia, Pa. -- While climate modelers are busy predicting changes in global, regional and local weather patterns, a team of Penn State researchers is trying to determine how those changes will affect everything from drinking water and agricultural production to flooding and public health. "Studying climate change is not just studying the global climate, but what the shifts in climate will do to specific regions," says Brent Yarnal, associate professor of geography. "The climate models are only a small part of an integrated regional assessment of global climate change."

Integrated assessment includes economic and social consequences of global change, the choices that can be made to mitigate or adapt to these changes, and the effects that humans have on climate change. The human elements, especially, feed back into the climate models as policy decisions alter greenhouse gases or, in other ways, affect climate change.

"Penn State's Center for Integrated Assessment (CIRA) focuses on the Susquehanna River Basin and uses overlapping projects to determine how regions and local municipalities contribute to and are affected by global change," Yarnal told attendees today (Dec. 17) at the annual meeting of the American Association for the Advancement of Science in Philadelphia. The Susquehanna River Basin begins near Otsego Lake in New York and, 444 miles later, empties into the northernmost part of the Chesapeake Bay. About 3.8 million people live in the 27,500 square miles of the basin, mostly in Pennsylvania but including small portions of New York and Maryland.

Geographic information systems and complex visualization are the subject of a project by Donna Peuquet and Alan M. MacEachren, both professors of geography, who are trying to put a fourth dimension -- time -- into the assessment. Working with enormous data sets that sometimes have blocks of data missing, the researchers try to capture the Susquehanna River Basin and track the changes through time.

Policy decisions on national, regional and local levels generally influence these changes. Ann Fisher, senior research associate, agricultural economics; Richard Bord, associate professor of sociology; and Robert O'Connor, associate professor of political science, are investigating how people evaluate the risk of global climate change.

"An interesting question is whether the person on the street views the risks in the same way that the policy makers do," says Yarnal. "Also, do perceptions change with scale? Are the risks considered acceptable on a national level, but not on a local level?"

Fisher, Bord and O'Connor look at how water resource managers in the Susquehanna River basin view their vulnerability to climate change. Water resources, especially drinking water, are important in another segment of the CIRA research. A project investigating the vulnerabilities of water resources to climate variation and change, found that the policy decisions made in the Clean Drinking Water Act actually reduce vulnerability to floods and drought.

"Inadvertently, the government, in trying to ensure clean drinking water through institution of the Act, made people in the area less vulnerable to floods and drought and climate change," says Yarnal. "However, areas with small, independent drinking water supplies are still vulnerable because they have been allowed to defer meeting the requirements or are exempt from them."

One thing that climate change will bring is an increased frequency of severe weather events, which increase the potential for flooding. Flooding can bring on epidemics of waterborne diseases like cryptosporidiosis, a diarrheal disease that can pose major health problems for the elderly, infants and those with compromised immune systems. Cryptosporidiosis is found through Pennsylvania in cattle feces and flooding could introduce the cysts into the drinking water system.

"A team of researchers led by Ann Fisher and colleagues at Johns Hopkins University found that only about half the people in an area actually follow boil water directives adequately or at all," says Yarnal.

Increased filtration, boiling water, drinking bottled water and trucking in water are all effective ways to avoid contamination. Balancing the expenses of water treatment with the cost to the community in deaths, hospitalizations, lost work and worker's compensation can establish an economically sound way to deal with potential outbreaks.

"Concerns about global warming are usually couched in worldwide or national terms," says Yarnal. "Our approach is to look at how changes in climate will influence people on a local and regional level."

Other researchers include Eric Barron, professor of geosciences; Jeff Carmichael, research associate Earth System Science Center; Robert Crane, professor of geography; William Easterling, associate professor of geography; Amy Glasmeier, professor of geography; Gregory Knight, professor of geography, Stephen Mathews, adjunct faculty in geography; Adam Rose, professor of energy, environmental and mineral economics; and J. Shortle, professor of agricultural economics.


EDITORS: Dr. Yarnal may be reached at (814) 863-4894 or at by email.

Penn State

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