CHURCHVILLE, VA—The Culbin Sands in Scotland are one of the famed historic storm sites in the world. In 1694, the area was rich farmland, with a manor house and numerous tenant farms amid the fields and orchards. Then a “western hurricane” struck the Firth of Moray, and in two nights the howling storm had buried the houses, orchards, and 14 square miles of fields under 30 feet of sand. The sand is there today, though now covered with Corsican pine trees planted in the 1920s to keep the sand from blowing onto neighboring lands.
President Obama recently warned the nation of “storms that are growing stronger with each passing hurricane season.” The Culbin Sands may help us find out whether such massive storms will or won’t be more common in the rest of the 21st century.
Two British researchers have examined the dune fields, which conspicuously dot the Atlantic coasts of Western Europe. Michelle Clarke of England’s Nottingham University and Helen Rendell of Loughborough University found the Culbin Sands—and much of the other notable storm evidence—dated between 1500 and 1900 AD. Those were the years of the Little Ice Age. They also found several earlier periods when dune-building storms were common—including the Dark Ages from 600 to 950 AD, the unnamed cooling before the Roman Warming, which ended about 200 B.C., and two strong cold periods in prehistory about 2000 and 4,000 B.C.
“The Holocene record of sand drift in western Europe includes episodes of [sand] movement corresponding to periods of Northern Hemisphere cooling” they report.
Note that they say “cooling’ Not “warming.” That’s logical, since storms get their power from the temperature differential between the polar regions and the equator. During a warm period, the Arctic may get 3–4 degrees C closer to the temperature of the equator, calming the storm activity. During a cold period, however, the Arctic and Antarctic may get up to 6–8 degrees cooler compared to the equator. This adds lots more power to the storms.
Clarke and Rendell use “optically stimulated luminescence” to date when grains of sand were first buried in a dune or sand sheet. These sand dates can be compared with carbon 14 dating of the associated peat and buried soils to produce a storm/calm history for a given piece of land. The Clarke and Rendell work confirms—again—the solar-linked 1,500-year warming-cooling cycle. These Dansgaard-Oeschger cycles shift global temperatures sharply every 700 years or so—usually about 2-4 degrees C at the latitude of New York and Paris.
If today’s warming had been caused by the Dansgaard-Oeschger cycles instead of by humans burning fossil fuels, the timing and the magnitude of the temperature change would both be about right. The cyclic forecast for the rest of the 21st century would then be for some modest extra warming, probably less than 0.5 degree C. This would probably come in a series of 30–40 year spurts up and down—like the past cooling that lasted from 1940 to 1975, and the warming that followed from 1976 to1998.
What about tropical hurricanes? The British Navy stationed wooden sailing ships in the Caribbean during the last part of the Little Ice Age. Their ships’ logs recorded more than twice as many major, land-falling hurricanes per decade from 1700 to 1850 as we’ve recoded in the last half of the 20th century.
Keep your home insurance current even so.
Sources:
President Obama’s storminess prediction—presented on videotape at the California Governor’s Conference on Global Warming, Nov. 18, 2008.
Dune-building storms of the past: Michelle Clarke and Helen Rendell, 2009, “The Impact of North Atlantic Storminess on western European coasts,” Quaternary International, Vol. 195, pp. 31-41.
British Navy Little Ice Age hurricane records compared with late 20th century: J.B. Elsner et al., 2000, “Spatial Variations in Major U.S. Hurricane Activity: Statistics and a Physical Mechanism.” Journal of Climate, Vol. 13, pp. 2293-2305.
