Kam-bui Liu may one day be known as the father of paleotempestology, the study of past tropical cyclone activity. According to an article in American Scientist, the term “Paleotempestology” was coined in 1996 by Kerry Emanuel, a meteorologist at the Massachusetts Institute of Technology, to describe Liu’s research techniques. The statistical data for hurricanes on the National Oceanic and Atmospheric Association Web site only lists statistics for storms as recent as the 1850s. While this information would be vital in the prediction of hurricane trends, there is no reliable documentation of the weather before this time. But this is changing due to the new research techniques created by Kam-bui Liu, paleotempestologist and professor in the Department of Oceanography and Coastal Sciences. Liu has spent the last 16 years digging core samples from the sediments beneath coastal lakes and marshes along the coast of the Gulf of Mexico. Liu studies the sand deposits found in the core samples in order to derive information about the powerful hurricanes of the past. “Basically we push the rods and tubs down to the bottom of the lake, and we raise a core of sediments,” Liu said. “By using this method and some strong graduate students, of course, we can get up to nine or 10 meters or about 30 feet of mud.” Liu then examines the sediments in the core samples for defined layers of sand, which signal the presence of a powerful hurricane from the past. “These layers of sand are derived from the sand dunes in front of the lake. The idea was that when a strong hurricane makes landfall, it creates a storm surge,” Liu said. “And the stronger the hurricane, the higher the storm surge. The storm surge would overtop the beach barrier and wash the sand from the beach and the dunes into the bottom of the lake, which will form a sand layer.” If there is a time period without any powerful hurricanes, the sediment at the bottom of the lake for that time would be dark and without sand, he said. “By identifying the sand layers and by radiocarbon dating to find out the age of each sand layer, we can get a prehistoric record of these very strong hurricane strikes going back as far as 5,000 years,” Liu said. Liu said the research does not detect minor hurricanes because only a Category 4 or Category 5 hurricane would have a strong enough storm surge to overtop the beaches or sand dunes. According to the NOAA Web site, a hurricane must have winds greater than 155 mph and a storm surge above 18 feet to be classified as Category 5. “This is like ‘paleohurricane’ CSI. We try to find the fingerprint or evidence left behind by these monster hurricanes,” Liu said. The data collected by Liu’s research shows a given location was hit about 10 to 12 times over the past 3,000 to 4,000 years, he said. This comes to an approximate average of one hit every 300 years. “For each year, on average, there is about a 0.3 percent probability for any place like New Orleans, Mobile or Pensacola to be directly hit by a Category 4 or Category 5 hurricane,” Liu said. Liu’s research is important because it gives insight into the probability of encountering a Category 5 storm based on data from as far back as 5,000 years. Previously, scientists could only predict hurricanes based on documented information from the past two centuries. “This kind of information is very important for engineers in deciding on the building codes for levees, bridges, roads and high-rises,” Liu said. “That is why a long-term geological record is absolutely necessary for our society to better prepare ourselves for the next storm to come.” Another important discovery from Liu’s work is evidence of a “hyperactive period” of hurricane activity on the gulf’s coast. Between 1,000 and 4,000 years ago there were three to five times as many hurricanes hitting the gulf coast than there have been in the past 1,000 years. “If we think we have seen the worst in the last couple of years, we haven’t seen anything yet,” Liu said. “The climate system is capable of delivering more hurricanes than what we can even imagine based on the historical record.” According to a University news release, Liu was recently granted $690,000 from the Inter-American Institute for Global Change Research for his new project “Paleotempestology of the Caribbean Region,” which will to run for five years. Liu said paleotempestology has branched out since the time he began his research. There are some new techniques that show potential, such as examining tree rings, stalagmite deposits in limestone caves and coral reefs, but the most proven technique is the one he pioneered 16 years ago, he said.
—–Contact David McCoy at [email protected]