UVM Geologists Predict Severe New England Weather
Release Date: 10-23-2002
Author: Lynda Majarian
Is New England headed for troubled waters? Significant storms and floods may be ready to wreak havoc, according to geologists at the University of Vermont. Their study of storm and flood patterns in the Northeast over the past 13,000 years will appear in the Oct. 24 issue of the journal Nature, the world's premier information resource for biological and physical sciences.
Funded by a National Science Foundation Career grant, Paul Bierman, professor of geology, led a team of colleagues and students in a four-year project to collect and study core samples from 21 lakes in Vermont and the Adirondacks. Among their conclusions: periods of intense storminess have peaked in the North Atlantic region roughly every 3,000 years over a 13,000-year period.
“The last big group of storms was – you guessed it – almost 3,000 years ago,” says Bierman, who co-authored the Nature paper with Anders Noren, former graduate student of geology at UVM; Andrea Lini, assistant professor of geology; and colleagues in Washington and California. While they cannot predict exactly when the next big storm will hit, the regional patterns they were able to establish are red flags to emergency planners, who rely on early detection to quickly evacuate people to higher ground when waters rise.
There was no time for warnings, preparations or escape when record rainfall overflowed rivers and partially submerged several Vermont towns in 1927, killing 55 people and destroying $30 million in property. But that disaster, says Bierman, was merely a drop in the bucket compared to earlier – and future – hydrologic hassles.
“If this cycle continues, the frequency and severity of intense rainstorms that can cause massive flooding should continue to increase for the next several hundred years,” agrees Noren, who is lead author of the Nature article. He joined Bierman’s research team as a graduate student and wrote his thesis on the project, building on the thesis of another geology graduate student, Sarah Brown. In a laborious process he calls “a wintry dance,” Noren spent long, cold days helping to collect sedimentary archives by hammering 20-foot pieces of 3-inch diameter PVC pipe into the bottom of frozen lakes and extracting core samples that were later sliced, photographed and painstakingly analyzed.
“In each of the cores we looked for sandy layers of sediment that were washed into the lakes during rainstorm-induced floods,” he explains. During “nor’easters,” cyclones and hurricanes, material stored in upland streams and basin hill slopes is eroded and transported to lake basins. “By getting radiocarbon dates on the organic materials in and around these layers, we were able to determine when floods occurred,” Noren notes. The study’s main conclusions were culled from an analysis of the flood chronologies of all the lakes.
“There may be much bigger floods than the 1927 disaster lurking out there,” Bierman says. “But the most important thing to come out of this research is that, for the first time, we know the history of stormy periods in New England over the past 13,000 years.” The storm rhythms observed in the UVM study are consistent with those recorded in the Greenland ice sheet, which carries signals in its chemical and physical properties that reflect an upswing in storminess over the past 600 years. It is suspected that the impact of human activity, especially the emission of atmospheric greenhouse gases, could speed up storm cycles.
Bierman has conducted additional research on alluvial fans, which collect debris from hill slopes and landslides. Those results support the data collected on regional storms, and will appear in the next issue of the Geological Society of America bulletin.
Noren graduated from UVM in May with a master’s degree in geology. He has returned to his native Minnesota and currently is a research technician at the Limnological Research Center at University of Minnesota in Minneapolis.
Read the Nature article, titled “Millennial-scale storminess variability in the northeastern United States during the Holocene epoch,” online at http://www.nature.com/nature.