Description
Working with a six-meter-long ocean sediment core and a shorter 80-cm-long core extracted from the bottom of the Blue Hole of Belize's Lighthouse Reef (17.5°N, 87.5°W), the authors measured the δ¹⁸O of the fine-grained calcium carbonate sediments contained therein. Then, they report that "after a δ¹⁸O high [(indicative of colder temperatures)], probably reflecting the end of the Migration Period Pessimum (AD 400-800), there is a long δ¹⁸O low during the Medieval Warm Period from AD 1000-1400, another δ¹⁸O high around AD 1500, representing the Little Ice Age, followed by a δ¹⁸O drop." And based on a graphical representation of their results, the MWP was likely cooler than the last two to three decades of the 20th century.