Little Ice Age clearly recorded in northern Greenland ice cores

Four ice cores drilled in the little investigated area of northern and northeastern Greenland were evaluated for their isotopic (δ18O) and chemical content. From these rather uniform records a stable isotope temperature time series covering the last 500 years has been deduced, which reveals distinct climate cooling during the 17th and the first half of the 19th century. Timing of the preindustrial temperature deviations agrees well with other northern hemisphere temperature reconstructions, however, their extent (∼1°C) significantly exceeds both continental records as well as previous southern and central Greenland ice core time series. A 20-30% increase in the sea salt aerosol load during these periods supports accompanying circulation changes over the North Atlantic. Comparison with records of potential natural climate driving forces points to an important role of the long-term solar influence but to only episodically relevant cooling during years directly following major volcano eruptions. © Copyright 1998 by the American Geophysical Union.