THE FROZEN IN BOSPHORUS AND ITS PALEOCLIMATIC IMPLICATIONS - A SUMMARY OF THE HISTORICAL DATA -

The first evidence of a frozen Bosphorus has been noted during the times of Herodotus. Analysis of the historical data about the freezing events in Bosphorus (Istanbul, Turkey) merits the presence of four main cold periods since 0 AD.

The first period was around the 1^st century. Although the temperature was close to or perhaps a little lower than, that of the present, Ovidius indicates 3 successive freezing events between 7-17 AD. The second cold period was in the 4^th century. At that time Scaliger reports another freezing event in 401 AD. Then there was a slight increase in temperature up to the beginning of the 8^th century. The third cold period extending from the middle of the 8^th century to the 13^th, during which the Bosphorus, and even parts of the Black Sea, were repeatedly frozen, and floating ice masses were present in the Sea of Marmara in 739, 753, 755, 762, 928, 934, 1011 and 1232. Winters were markedly mild for 400 years from the middle of the 13^th century to the middle of the 17^th. The fourth colder period starting in the early middle of the 17^th century and lasting up to the present day was characterized by severe winters (with freezing of the Bosphorus, the Golden Horn and parts of the Black Sea in 1620, 1669, 1755, 1823, 1849, 1862, 1893, 1929, 1954). However, the intensity of the winter cold has gradually diminished during this interval.

These four episodes are more or less contemporaneous with the phases of glacial advances in the Northern Hemisphere. As the accuracy of the historical data increases with time, evidences of events are more condense in the fourth period. During this interlude that coincides with the Little Ice Age, freezing events are not all contemporaneous with the central European evidences. This can be explained by the low index of North Atlantic Oscillation that resulted in higher precipitation ratios.

Currently, the examination of glacial features in Anatolia contributes little to the interpretation of the Quaternary paleogeography and climate, and investigations of glacial features are incomplete and a sound chronology is non-existent. Our aim is to evaluate existing historical data on the modern cold periods, to analyze instrumental meteorological data and to correlate with the amplitude and frequency of paleoglacier advances both in the Alps and in Anatolia.