Speleothem records decadal to multidecadal hydroclimate variations in southwestern Morocco during the last millennium

•High resolution reconstruction of hydroclimate variability during the last millennium in Southwestern Morocco.•Coherent regional climate signals showing dry conditions during the MCA and the CWP and wetter conditions during the LIA.•Substantial responses to the AMO, NAO and Sahara Low over the hydroclimate variability in Southwestern Morocco.

This study presents the first well-dated high resolution stable isotope (δ18O and δ13C) and trace element (Mg and Sr) speleothem records from southwestern Morocco covering the last 1000 yrs. Our records reveal substantial decadal to multidecadal swings between dry and humid periods, consistent with regional paleorecords with prevailing dry conditions during the Medieval Climate Anomaly (MCA), wetter conditions during the second part of the Little Ice Age (LIA), and a trend towards dry conditions during the current warm period. These coherent regional climate signals suggest common climate controls. Statistical analyses indicate that the climate of southwestern Morocco remained under the combined influence of both the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) over the last millennium. Interestingly, the generally warmer MCA and colder LIA at longer multidecadal timescales probably influenced the regional climate in North Africa through the influence on Sahara Low which weakened and strengthened the mean moisture inflow from the Atlantic Ocean during the MCA and LIA respectively.