"Among the most vocal of the cadre of scientists who have questioned some of the IPCC's recent work is John R. Christy, director of the Earth System Science Center at the University of Alabama-Huntsville and a former contributor to a big 2001 IPCC report. He, like several other of the critics, was repeatedly criticized in the hacked emails.
Dr. Christy spent years comparing temperature data from satellites with ground stations. He concluded that the reliance on a few well-known ground-based measuring stations may vastly overstate how much temperatures have risen. He suggests that surface temperatures are actually measuring an increase in human development—more and bigger cities, more asphalt, more air-conditioning—and not rising temperatures in the atmosphere. Most climate scientists, by contrast, ascribe rising temperatures largely to man's introduction of greenhouse gases into the atmosphere.
Some dissenters have focused on the complex effect of clouds. Richard Lindzen, a professor of meteorology at the Massachusetts Institute of Technology and a past contributor to an IPCC report, says that the role of clouds and water vapor—the main greenhouse agents in the atmosphere—is one of the least understood factors in climate science. It's a limitation that the IPCC acknowledges.
Prof. Lindzen says the key issue is "climate sensitivity"—how much will temperatures rise when carbon-dioxide levels double. He asserts that current climate models include a "positive feedback" effect whereby clouds and water vapor act to amplify CO2's greenhouse effect. In response to a doubling of carbon-dioxide levels, the IPCC has found climate sensitivity to be between 1.5 degrees and five degrees Fahrenheit. Prof. Lindzen says those figures, derived from models, overstate the case.
Prof. Lindzen recently published a study based on radiation measurements taken from satellites—not models—and concluded that climate sensitivity as a result of clouds and water vapor was more likely in the 0.3 degrees to 1.2 degrees range, much lower than the figure accepted by most climate researchers. "The observational analysis implies that the models are exaggerating climate sensitivity," he concludes in a second, yet-to-be published paper on the same subject.
Dr. Willie Soon, a professor at Harvard University, believes that changing levels of solar radiation, especially the amount that hits the Arctic, are driving huge, slow changes in the earth's climate—much as they did in past centuries. The theory rests on the fact that the sun emits different amounts of energy at different times."
Wednesday, February 17, 2010
Climate-Research Controversies Create Opening for Critics
From the Wall Street Journal (2/16/10):
Posted by MS at 11:35 AM