Mangini, A., Verdes, P., Spotl, C., Scholz, D., Vollweiler, N. and Kromer, B. 2007. Persistent influence of the North Atlantic hydrography on central European winter temperature during the last 9000 years. Geophysical Research Letters 34: 10.1029/2006GL028600.
Based on an analysis of δ18O data obtained from three stalagmites (SPA 12, SPA 128, SPA 70) found within Austria's Spannagel Cave (47.09°N, 11.67°E), Mangini et al. (2007) developed what they demonstrated to be a regional δ18O history covering the last 9000 years; and applying the calibration curve derived for SPA 12 by Manginni et al. (2005) to the new δ18O curve, it can readily be determined that the peak temperature of the Medieval Warm Period (AD 800-1300) was approximately 1.5°C higher than the peak temperature of the Current Warm Period.