HOLOCENE

Abstract: Varved sediments from Nicolay Lake, Canadian High Arctic, record major summer rainfall events over the last five centuries. Increased incidences of summer rainfall occurred during the coldest periods of the 'Little Ice Age ' and were strongly clustered in the years ininiediately following major volcanic events. Compari-son of the summer rainfall and proxy air temperature records thus provides a fuller understanding of the natture and causes of natural climate variability in the Arctic. Study of the synoptic conditions associated with the two most recent large summer rainfall events suggests that they are associated with the incursion of cold low-pressure systems from the Arctic Ocean Basin. Volcanic activity may produce atmospheric conditions more conducive to the fornation of such low-pressure systems, which generate rainfall at low elevations and summer snowfall at higher elevations, thus explaining the correlation between rainfall and summer snow accumulation recorded in ice cores from high-elevation ice caps