Climatic signal of ice melt features in southern Greenland

Abstract

The stratigraphie record of melt features in intermediate depth polar ice cores has provided valuable data on past summer climate1–3. The thermal drilling technique used in previous studies precluded extending this record beyond a few hundred years. Recently, however, a 901-m deep ice core was mechanically drilled in southern Greenland. The excellent core quality and improved techniques for measuring melt features have resulted in an ∼2,200 yr record with consistently high quality data. We report here that the temporal variations in melt feature abundance, expressed as annual melt per cent (AMP), provide proxy data on summer climate that can complement other records extending back thousands of years. The AMP profile indicates that relatively warm summers prevailed from about AD 950 until AD 1500 culminating in the thirteenth and fourteenth centuries. The periods from about 300 to 150 BC, AD 350 to 550, and AD 1550 to 1800 had relatively little summer melting.