Abrupt Climate Changes

THROUGHOUT RECORDED HISTORY, and in studies of geological and other records from much earlier periods of the Earth's history, there have been a number of abrupt climate changes. These significant and widespread shifts in climate heavily impacted many parts of the world. Current studies of these changes draw from details revealed from ice core samples, especially from Greenland and northern Canada, and also from records compiled showing signs of geological changes. More recent information has emerged from examinations of the fluctuations in the size of tree rings, and also from historical accounts.

The quantity of these abrupt climate changes has led some academics, often labelled climate change skeptics, to explain the current global warming in terms of these trends. They suggest or state that the current changes are, or could be, merely a part of a cycle of global warming and cooling, similar to those that have occurred over hundreds of thousands of years.

Explaining global warming in the 1990s and 2000s by studying these abrupt climate changes gained much publicity around the world through the article “A Pervasive Millennial-Scale Cycle in North Atlantic Holocene and Glacial Climates,” which was written by ten leading scientists, Drs, G, Bond, W. Showers, M, Chesby, R, Lotti, P, Alamsi, P, de Menocal, P, Priore, H, Cullen, I, Hajdas, and G, Bonani, and published in the journal Science in November 1997, This article, and related work, led to a substantial body of research on abrupt climate changes—when the Earth's temperature has either significantly increased or decreased over a short period of time—and also the possible causes of these changes, A development of this theory came from two other scientists associated with those skeptical of global warming, S, Fred Singer of the University of Virginia, and Dennis Avery of the Hudson Institute in New York, They raised the possibility of a fifteen hundred year climate cycle, especially in the North Atlantic region, with hot temperatures every 1,500 years, The present global warming could be a part of this cycle. Certainly a part of this theory clearly rests on the extreme weather patterns experienced around the world during the years 535–36 CE. They are recorded by the Byzantine historian Procopius, and also in Irish annals, as well as in records kept in China—all showing that the climate change occurred across a large number of areas. [Page 2]

The Little Ice Age, which lowered world temperatures from about 1600 to 1750, froze large rivers and canals in Europe. This engraving depicts a fair held on the ice of the frozen River Thames in London in 1683.

These historical accounts are confirmed by a tree ring analysis undertaken by the dendrochronologist Mike Baillie from Queen's University of Belfast, Northern Ireland, which showned little growth in Irish oak trees during this period. Similar data emerging from a study of tree ring samples conducted on trees from Scandinavia, California, and Chile. The rise in temperature during these years seems to have led to a widespread series of famines around the world, and the collapse or destruction of a number of empires including that of the Persians, and the Mesoamerican city of Teotihuacan.

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