Long-term changes in soil water tables over the past 4500 years: Relationships with climate and North Atlantic atmospheric circulation and sea surface temperature

A record of mean annual water table changes in England over the past 4500 years is derived from a transfer function applied to protozoan assemblages in peat profiles. A 100-year running mean value based on three profiles shows short-term changes which are closely related to instrumental records of mean annual temperature changes (past 300 yr) and documentary records of summer wetness and winter severity (past 900 yr). Long-term (> 1000 yr) changes in this composite record are positively correlated with the GISP2 ice accumulation record, suggesting moisture budgets were in phase across the North Atlantic region over at least the last 2000 years and probably changed due to north-south movements of major pressure centres. This hypothesis is further supported by comparisons with indicators of sea surface temperature and ocean circulation. Existing regional climate predictions may underestimate the impact of future warming on soil moisture status, with significant implications for agriculture and water supply in northwestern Europe.