Late Holocene northeastern Morocco hydroclimate reconstruction revealed from speleothems d18O record
Wednesday, 17 December 2014
Two well dated oxygen isotope (d18O) records of speleothems collected in Chaara cave located in the Northeastern Morocco are used to investigate variations in hydroclimate conditions during the last 2000 years. The results shown in this work confirm the previous works of the North Atlantic Oscillation (NAO) reconstruction during the last millennium and bring new implications concerning its evolution extending the MCA. Our (d18O) results characterized by positive values during the Medieval Warm Period (MWP) and more negative ones during the Little Ice Ages (LIA) are in agreement with those published by Trouet et al., 2009 and Wassenburg et al., 2013. They confirm that the both periods were dominated by persistent NAO+ and NAO-conditions respectively. In addition; they highlight new evidence of the NAO evolution to beyond the last 1000 years. NAO+ conditions recorded during the MCA persist until 500 AD and NAO- conditions dominate the Dark cold Period (DACP) as recorded during the LIA. Finally, the Current Warm Period (CWP) was marked by a clear change in isotope variations linked to decreased precipitation controlled by intensification in NAO + conditions.