Questioning the effect of climate change

A recent study conducted by a USF graduate has climate scientists at odds over what effect rising global temperatures have on hurricane formation in the Atlantic.

The study, conducted by National Oceanic and Atmospheric Administration (NOAA) researcher and USF St. Petersburg graduate Chunzai Wang, was published Jan. 23 and proposes that, contrary to popular belief, increasing global temperatures could decrease the amount of hurricanes that reach landfall in the U.S.

After compiling data from Atlantic Ocean-based hurricanes that made landfall in the U.S. over the last 150 years, Wang claims that an increased global sea temperature could have a preventative effect on the formation of tropical storms in the Atlantic.

“Three oceans – the Atlantic, the Pacific and the Indian – compete with each other for the effects on Atlantic hurricanes,” Wang said. “If the Atlantic Ocean warms up, then we have an increase in hurricanes. However, if the Pacific or the Indian oceans warm up, it decreases Atlantic hurricanes. The total effect depends on which ocean temperature change is larger.”

Observations have shown that a rise in the sea surface temperature of the Indian or Pacific oceans causes an increase in vertical wind shear over the Atlantic, according to the study. Depending on many other factors such as sea surface temperature, atmospheric humidity and sea level pressure, the increase in wind shear could decrease the amount of storms that are formed.

While Wang’s study provides a fresh perspective on the possible effects of global warming on the planet’s climate, there are many scientists disputing the accuracy of the report.

The study’s most notable critic is the Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC), which said that Wang’s study is based on “poor data,” citing that “one in 10 North Atlantic hurricanes hit the U.S. coast, and the data reflect only a small percentage of storms around the globe.”

Wang disputed the IPCC’s statement, saying: “U.S. landfalling hurricanes account for about one third of the total North Atlantic hurricanes instead of ‘one in 10.'” He also said that U.S. landfalling hurricanes account for about 5 percent of all global ocean basin hurricanes. While this is a small percentage, Wang believes that studying the history of landfalling hurricanes is the most reliable method of detecting the long term trends of the storms, considering that the contemporary methods of study – namely the use of aircraft and satellites – have only been used since the mid-1940s and mid-1960s, respectively.

While the IPCC’s refusal to endorse Wang’s study might hurt its credibility in the eyes of some members of the scientific community, many in the field recognize that its opinions are not necessarily absolute.

“The IPCC is a recognized body that publishes a report every five years on the state of the climate,” said Jennifer Collins, an assistant professor of geography at USF. “They generally provide the consensus of what climate scientists think, but even though they provide that report, not all scientists agree with what they report.”

Collins feels that while the backing of the IPCC does add a degree of authority to a study, the lack of endorsement does not automatically disprove its claims.

“It’s important to have their backup because a lot of people hear IPCC and they feel that there’s a certain authority to it,” Collins said. “But I feel if you don’t have the IPCC backing you up, it doesn’t mean that your findings are no good, because there’s a lot of scientists in the past who came up with ideas that didn’t go with the general thinking at the time, and it was only later, after other people provided more evidence that backed up their ideas, that they were accepted.”

Like many others, Collins is reluctant to take the assertions of Wang’s study as fact just yet. Along with sea surface temperature, atmospheric humidity and vertical wind shear, hurricane formation is influenced by many other factors, including the effects of El Nino and La Nina – a global ocean-atmospheric phenomenon that affects ocean and weather patterns – and other long-term atmospheric patterns. With such a wide range of factors contributing to hurricane formation, Robbins feels more evidence will need to be presented before Wang’s theory can be fully accepted or dismissed.

“It is really just a piece of the evidence,” Collins said of Wang’s study. “But then other evidence indicates the opposite effects, so it requires scientists gathering all the evidence and balancing it all. It’s perhaps a bit too early to tell, and we’ll just have to keep gathering all the evidence.”