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Dr. John Christy is a climate scientist whose chief interests are global climate change, satellite sensing of global climate, and paleoclimate. He is best known, jointly with Dr. Roy Spencer, for his version of the satellite temperature record. He is a professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville (UAH). He was a key contributor to several IPCC reports, participating with lead authors in the drafting sessions, and in the detailed review of the scientific text. He was appointed Alabama's State Climatologist in 2000. For his development of a global temperature data set from satellites he was awarded NASA's Medal for Exceptional Scientific Achievement, and the American Meteorological Society's "Special Award."

Christy was a lead author for the 2001 UN report by the Intergovernmental Panel on Climate Change and the US CCSP report Temperature Trends in the Lower Atmosphere - Understanding and Reconciling Differences . He received his Ph.D degree in Atmospheric Sciences from the University of Illinois. He also has a master's degree in divinity from Golden Gate Baptist Theological Seminary.

Christy is generally considered a contrarian on some global warming and related issues, although he helped draft and signed the American Geophysical Union statement on climate change . In an interview with National Public Radio about the new AGU statement, he said: It is scientifically inconceivable that after changing forests into cities, turning millions of acres into irrigated farmland, putting massive quantities of soot and dust into the air, and putting extra greenhouse gases into the air, that the natural course of climate has not changed in some way.

More recently, in a study presented to the Washington Roundtable on Science and Public Policy he said:

• "I showed some evidence that humans are causing warming in the surface measurements that we have but it is not the greenhouse relation."

• Christy has also said that while he supports the AGU declaration, and is convinced that human activities are a cause of the global warming that has been measured, he is "still a strong critic of scientists who make catastrophic predictions of huge increases in global temperatures and tremendous rises in sea levels."

The climate trend shown by the satellite data has changed through time, as the climate has varied. During the first several years of data collection the global trend was downward. That has since changed and the most recent long-term average global climate trend seen in the satellite data is +0.14 C (about 0.25° Fahrenheit) per decade, due in large part to warming that began with the 1997-1998 "El Niño of the Century" Pacific Ocean warming event. Average global temperatures from 2001 through 2006 were mostly warmer than their baseline (1979-1998) norms.

Unlike some other major climate data sets, the satellite data are constantly being refined and adjusted as new discoveries are made in the relatively new science of remote sensing. Notable adjustments were made to compensate for the effects of orbital drift and orbital decay. Christy and Spencer use intercalibration between instruments on different satellites to adjust for instrument bias, then confirm the accuracy of their data by comparing it to data gathered by weather balloons and surface stations.

A native of Fresno, CA (where he learned to pan for gold), Christy was a missionary in Kenya for two years. After earning his divinity degree he founded a Southern Baptist church in South Dakota before pursuing a career in science and teaching.

External links

• Homepage
• 1997 hearing before the Senate Committee on Environment and Public Works
• Christy's Satellite Data

• Climatologists
• Global warming skeptics