John Christy

Dr. John Christy says increasing greenhouse gases have had no significant impact on the State of Alabama.

Michael Mercier | UAH

A new report by Alabama State Climatologist and University of Alabama in Huntsville (UAH) professor Dr. John Christy says that increasing greenhouse gases (GHGs) in the atmosphere have had no significant impact on the State of Alabama.

Dr. Christy’s report, “A Practical Guide to Climate Change in Alabama” contains charts and graphic representations that he says show numerous and important Alabama climate variables.

Dr. Christy is the distinguished professor of Atmospheric Science and director of the Earth System Science Center (ESSC) at UAH, a part of the University of Alabama System. He also serves as UAH’s interim vice president for research and economic development.

Beginning in 1979, Dr. Christy teamed with Dr. Roy W. Spencer – then a NASA scientist and now an ESSC principal research scientist – to develop a global temperature data set from microwave data observed by satellites. For this achievement, the Christy-Spencer team was awarded NASA's Medal for Exceptional Scientific Achievement in 1991.

Dr. Christy says the word “practical” in his report’s title was used for a specific purpose.

“The word practical was used because of the dynamic nature of the topic,” he says. “Few issues have been so politicized while simultaneously fraught with a lack of scientific understanding regarding the changes in our climate, whether considering Alabama, the United States or the entire globe.”

According to Dr. Christy, the latest theoretical climate model simulations have been unable to replicate the types of changes in climate variables that Alabama has experienced since the late 19th century and so they offer little guidance for the future.

In his report, he says that during the past half-century, Alabama’s sea level has risen at variable rates along the Gulf Coast, and he says a reasonable estimate for the Alabama portion is a continued rate-of-rise of about 1 inch to 1.5 inches per decade.

Dr. Christy says that any climate variable will show some type of change between different periods, whether those periods are weeks, months, years or millennia. He says we can’t know for certain why such changes occur because the climate system is an expression of two chaotic and turbulent fluids – the atmosphere and the ocean – which together can create an infinite variety of weather and climate patterns all on their own.

“Included in this report, we demonstrate the lack of changes from greenhouse gases through charts and visual representations on variables in Alabama’s weather,” Dr. Christy says.

He listed those variables: Changes in temperature; changes in temperature extremes; temperature changes in the future; changes in precipitation; changes in precipitation extremes; changes in drought; changes in snowfall; changes in sea level; changes in hurricanes; and changes in tornadoes.

“This report provides a tour through the climate metrics that are of interest to Alabamians, displaying how they have varied and changed over time,” Dr. Christy says.

“As indicated, there hasn’t been a detectable impact on these metrics from the extra greenhouse gases,” he says. “These GHGs, for the foreseeable future, will continue to accumulate in the atmosphere as a result of energy production that sustains human life – we just haven’t been able to detect with confidence their impact on climate in Alabama.”