Local or Global Problem?


Though their results drew national media attention from many sources, all the scientists involved in the research agree that the scientific arena is where the results should be evaluated. Pielke hopes these results will convince scientists to give the land cover-climate connection more attention. In the past, he has been frustrated by the lack of attention to the topic.

Gordon Bonan is a climate modeler for the National Center for Atmospheric Research in Boulder, Colorado. “It’s definitely true that historically, the emphasis in global climate change research has been on other climate forcings—greenhouses gases, solar variability, aerosols—and that the role of land cover has been neglected. Roger’s work, his persistence, has really played a large role in bringing people around to the importance of it.” Bonan thinks people are finally beginning to listen.

So far, what research has been done on the global-scale influence of land cover change on climate seems to suggest it plays a minor role. That’s not surprising, says Bonan, considering how small the Earth’s land surface is compared to its oceans and that our most common metric for climate change is global mean temperature. Even significant changes in the temperature where we live can get “washed out” (at least for a while) in the global average of a world mostly covered by oceans.

“Nobody experiences the effect of a half a degree increase in global mean temperature,” Bonan says. “What we experience are the changes in the climate in the place where we live, and those changes might be large. Land cover change is as big an influence on regional and local climate and weather as doubled atmospheric carbon dioxide—perhaps even bigger.” That’s the idea Pielke says he has been trying to get across for years. “Climate change is about more than a change in global temperature,” he says. “It’s about changes in weather patterns across the Earth.” Even if it turns out that land cover change doesn’t significantly alter the globally-averaged surface temperature of the Earth, it’s still critically important. “The land is where we live. This research shows that the land itself exerts a first order [primary] influence on the climate we experience.”

If land cover change can cause Florida to have hotter, drier summers and chillier, longer-lasting cold spells, then that is a perfect example of why, Pielke says, “we can’t keep looking solely at increasing carbon dioxide as the only important forcing of climate by people.”

  • References
  • Davis, Steven M., and John C. Ogden. 1994. Everglades: The Ecosystem and Its Restoration. Delray Beach, FL: St. Lucie Press.
  • Marshall, C.H. Jr., R.A. Pielke Sr., L.T. Steyaert, and D.A. Willard. 2004. The impact of anthropogenic land-cover change on the Florida peninsula sea breezes and warm season sensible weather. Monthly Weather Review. 132: 28-52.
  • Marshall, C.H., R.A. Pielke Sr., and L.T. Steyaert. 2004. Has the conversion of natural wetlands to agricultural land increased the incidence and severity of damaging freezes in south Florida? Monthly Weather Review. 132: 2243-2258.
  page 4

Print this entire article