Orbital, ice sheet, and possible solar controls on Holocene moisture trends in the North Atlantic drainage basin

Abstract

Holocene patterns of hydroclimatic change in the North Atlantic region are poorly understood despite the importance to climate of the region9s freshwater flux to the ocean. Here we reconstruct the history of moisture balance in the North Atlantic drainage by compiling lake-level records from 95 lakes in Europe and North America. We show that recent millennia were significantly wetter than much of the Holocene in both regions. Only 15% of lakes studied in the North Atlantic basin were low in the past millennium. In contrast, 50% of lakes were low at 10 cal kyr B.P. Low moisture levels in the early Holocene likely resulted from high summer and fall insolation and the influence of the continental ice sheets; water levels rose in many areas as these influences diminished. A principal components analysis of the lake-level data, however, also indicates that Holocene atmospheric circulation changes, possibly driven by solar activity, generated additional moisture variation, including low water levels at 5–2 cal kyr B.P. in eastern North America and Scandinavia.