With some help from the massive eruption of a Philippine volcano, scientists from North Carolina State University and the National Climate Center of China believe they have solved a climate change mystery.
That mystery, which has puzzled meteorologists in recent years, involves long-term climate trends in the southeastern United States and eastern China. According to experts' predictions, temperatures should warm globally, but should cool in both regions because of the presence of manmade air pollutants called aerosols. But while the Southeast has seen a mild cooling trend, the climate in China has actually warmed slightly over the last 50 years.
Dr. Vinod Saxena, NC State professor of meteorology, says the opposite temperature trends may result from the presence of differing types of aerosols, or airborne particulate matter, in the atmosphere over China and the southeastern United States.
Saxena and his colleagues outline their findings in the Feb. 15 issue of the peer-reviewed journal Geophysical Research Letters.
"The Southeast receives sulfate aerosols blown over the Appalachians from industrial manufacturing in the Ohio River Valley," Saxena explained. "Sulfate aerosols are believed to decrease temperatures by having the same effect as painting a house roof white: They reflect solar radiation back into space.
"The aerosols over eastern China are mostly carbon soot particles from the burning of coal and wood for cooking and heating, and from unregulated industrial emissions," he said. Those aerosols tend to result in higher temperatures by absorbing solar radiation especially in the winter, when more coal and wood is burned.
The research by Saxena and his colleagues found that the amount of carbon soot pollution over China increased during the last half century, at the same time average annual temperatures nudged upward. The temperature increase was most pronounced during the winter months.