is the study of past tropical cyclone
activity by means of geological proxies as well as historical documentary records. The term was coined by Kerry Emanuel
Sedimentary proxy records
Examples of proxies include overwash deposits preserved in the sediments
of coastal lakes and marshes, microfossils
such as foraminifera, pollen, diatoms, dinoflagellates, phytoliths contained in coastal sediments, wave-generated or flood-generated sedimentary structures or deposits (called tempestites) in marine or lagoonal sediments, storm wave deposited coral shingle, shell, sand and shell and pure sand shore parallel ridges.
The method of using overwash deposits preserved in coastal lake and marsh sediments is adopted from earlier studies of paleotsunami deposits. Both storms and tsunamis leave very similar if not identical sedimentary deposits in coastal lakes and marshes and differentiating between the two in a sedimentary record can be difficult. The first studies to examine prehistoric records of tropical cyclones occurred in Australia and the South Pacific during the late 1970s and early 1980s. These studies examined multiple shore parallel ridges of coral shingle or sand and marine shells. As many as 50 ridges can be deposited at a site with each representing a past severe tropical cyclone over the previous 6,000 years. Tsunamis are not known to deposit multiple sedimentary ridges and therefore these features can be more easily attributed to a past storm at any given site.
Coastal sedimentary analyses have been done at the U.S. Gulf coast, the Atlantic coast from South Carolina up to New Jersey and New England, and the Carribean sea. Also, studies on pre-historic tropical cyclones hitting Australia have been made. A study covering the South China Sea coast is soon to be published.
Markers in coral
Rocks contain certain isotopes of elements, known as natural tracers, which describe the conditions under which they formed. By studying the calcium carbonate in coral rock, past sea surface temperature and hurricane information can be revealed. Lighter oxygen isotopes (18O
) are left behind in coral during periods of very heavy rainfall. Since hurricanes are the main source of extreme rainfall in the tropical oceans, past hurricane events can be dated to the days of their impact on the coral by looking at the increased 18
O concentration within the coral.
Speleothems and tree rings
Isotope studies in speleothems and tree rings offers a means by which higher resolution records of long-term tropical cyclone histories can be attained. Unlike the isotope records, the sedimentary records are too coarse in their resolution to register quasi-cyclic activity at decadal to centennial scales. These higher resolution records therefore offer a means for possibly differentiating between the natural variability of tropical cyclone behaviour and the effects of anthropogenically induced global climate change. Recent studies with stalagmites in Belize
shows that events can be determined on a week-by-week basis.
Before the invention of the telegraph
in the early to mid 19th century, news was as fast as the quickest horse, stage, or ship. Normally, there was no advance warning of a tropical cyclone impact. However, the situation changed in the 19th century as sea-faring people and land-based researchers, such as Father Viñes in Cuba
, came up with systematic methods of reading the sky's appearance or the sea state, which could foretell a tropical cyclone's approach up to a couple days in advance.
Michael Chenoweth used 18th century journals to reconstruct the climate of Jamaica.
In China, the abundance of historical documentary records in the form of Fang Zhi (semiofficial local gazettes) offers an extraordinary opportunity for providing a high-resolution historical dataset for the frequency of typhoon strikes.
- Elsner, James B.; Kara, A. Birol (1999). Hurricanes of the North Atlantic: Climate and Society. New York: Oxford University Press.
- Liu, Kam-biu (2004). Hurricanes and Typhoons: Past, Present, and Future. New York: Columbia University Press.
- Paleotempestology. In Encyclopedia of Quaternary Science (3, 1978–1986). (2007). Elsevier. .
- Nott, Jonathan (2004). "Palaeotempestology: the study of prehistoric tropical cyclones—a review and implications for hazard assessment". Environment International 30 (3): 433–447.
- Revkin, Andrew C. "Experts Unearth a Stormy Past". New York Times. .