Banded corals:

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" Banded corals: "
Druffel, ER

Document Type	:	AL
Record Number	:	917998
Doc. No	:	LA47m0g3fv
Title & Author	:	Banded corals:. Changes in oceanic 14C levels during the Little Ice Age [Article]\ Druffel, ER
Date	:	1982
Title of Periodical	:	UC Irvine
Abstract	:	Radiocarbon analyses and stable isotope measurements are presentedfor two recent cores of banded corals from the Florida Straits. These values provide arecord of variations in the ratio of carbon-14 to carbon-12 in the dissolved inorganiccarbon in the surface waters of the Gulf Stream from A.O. 1642 to 1800. An increasein the carbon-14/carbon-12 ratio of 7 per mil for coral growth during the early 1700'swas most likely induced by an increase in the carbon-14/carbon-12 ratio of 20 per milin the atmospheric carbon dioxide that occurred at about 1700. The ratios of oxygen-18 to oxygen-16 in these coral bands show a small decrease of water temperature(- 1°C) during the latter part of the Little Ice Age (1700 to 1725). These resultssupport the hypothesis that the increase in atmospheric carbon-14 at about 1700, andpossibly the temperature change as well, was caused by a decrease in solar activity(Maunder sunspot minimum).