Loch Lomond Stadial (Younger Dryas) glaciers and climate in Wales



Former cirque glaciers in the Aran and Berwyn mountains, North Wales, indicate a cold and wet climate during the Loch Lomond Stadial (Younger Dryas), with values of annual accumulation close to modern values of precipitation. Climate at the equilibrium line altitude (ELA) of these glaciers was reconstructed using a simple degree–day melt model and a regression relationship between summer precipitation + winter balance. These different approaches utilized published palaeoecological proxy data to isolate summer temperature and annual temperature range, in order to reconstruct values of annual accumulation and summer precipitation+winter balance. The degree–day model predicts that annual accumulation of 1920–2586 mm water equivalent (w.e.) would have been required to offset ablation, whilst the regression approach predicts a value of 2428–2985 mm w.e. for summer precipitation + winter balance. The degree of divergence between values of annual accumulation and summer precipitation + winter balance calculated by the two approaches depends on summer temperatures and also annual temperature range, which effectively determine the proportion of precipitation that falls as rain or snow. Copyright © 2009 John Wiley & Sons, Ltd.