Expert: Global warming evidence inconclusive

William Evans

During the transition from winter to spring, weather patterns in Tuscaloosa can disrupt a student’s expectations for what clothing to wear when the temperature seems to shift from day to day.

The dynamic temperature shifts are representative of the climate pattern in the southeastern United States and do not show support for the theory of global warming, said John Christy, climate scientist at the University of Alabama at Huntsville.

“This is the time of year when weather patterns can change drastically,” he said. “You are in winter in Alabama. This is what happens.”

Christy, appointed as the state climatologist in 2000, said rapid temperature changes experienced in Tuscaloosa occur because of the effects produced by sea surface temperatures in the Pacific and northern Atlantic oceans.

Whereas the pattern from the Pacific tends to create warmer and drier weather along the Gulf Coast, the pattern from the northern Atlantic tends to generate colder weather.

Christy said the models he uses to scrutinize the theory of global warming fail to support the argument climate scientists make in support of human-induced climate change.

“To date, we haven’t found that signal that says, ‘This is clear evidence that humans are causing changes of temperature in the weather,’” he said.

He said although greenhouse gas emissions have a warming effect on the atmosphere, some factors in the global climate may be mitigating the warming effect of carbon dioxide vapors.

The convergence of the four seasons during wintertime in Tuscaloosa has produced extreme temperatures but has not led climate scientists to conclude that global warming is the cause, said Jason Senkbeil, assistant professor of geography and the director of the environmental science program.

“In the past year, we have had some seasonal extremes, but it is too short of a time period to jump to conclusions,” he said. “In the southeastern United States, there has not been any statistical evidence of climate change.”

For many southeastern states, the summer of 2010 was the hottest summer to be recorded in a 116-year period, and the current winter will become the top 10 coldest to be experienced, he said.

The weather, however, still follows a predictable pattern, which causes the global warming theory to fall short of being an indisputable fact, he said.

The majority of climate scientists in The Intergovernmental Panel on Climate Change, an intergovernmental body of scientists tasked with providing information on climate change and its consequences, support the theory of global warming, he said.

“The majority of the world’s climate scientists believe there is a human relationship to climate change,” he said.

In a 2007 editorial to the Wall Street Journal, Christy distanced himself from the majority by siding against the consensus on global warming.

“I’m sure the majority (but not all) of my IPCC colleagues cringe when I say this, but I see neither the developing catastrophe nor the smoking gun proving that human activity is to blame for most of the warming we see,” he wrote.

A host of climate patterns lead to the fickle weather experienced in Tuscaloosa during this time of year, which lie outside of the global warming debate, said Kristina Sumrall, observing program manager for the National Weather Service in Birmingham.

“Outside of the whole global warming scenario, there are numerous large risk patterns that affect our climate, and those patterns occur over decades,” she said.