Major Hydroclimate shifts in Europe during severe glacial periods (MIS 16 and MIS 12)

Global warming and unprecedented increase in CO2 urgently call for improved understanding of the climate system. The acceleration of ice sheet and sea ice melting, the weakening of the Atlantic Meridional Overturning Circulation (AMOC) to a tipping point for its collapse, and the observed anomalous distribution of heat in the North Atlantic region are severely contributing to an intensification of climate hazards (droughts, wildfires, storms and floods) in vulnerable regions. Understanding ocean-atmosphere dynamics and its role in precipitation distribution and intensification of hydroclimate hazards in highly vulnerable regions, as SW Europe, is a key priority.
We studied two severe glacial periods such as the Marine Isotopic Stages (MIS) 16 (621–676 ka) and MIS 12 (424–478 ka) and their terminations (TVII:  ~ 625 kyr and part of the TV: ~ 430 kyr, since there is a hiatuses). Each glaciation was characterised by expanding global ice-sheets from the time of glacial onset to the beginning of the deglaciation and are marked by instabilities of Northern Hemisphere ice sheets during the glacial inception, before the peak glaciation and during deglaciation. Northern Hemisphere ice sheets instabilities are however stronger after the peak glacial as revealed by maxima of ice-rafted detritus deposition in the North Atlantic. The major difference between the two glacials has been attributed to a more northern position of the Artic front during MIS 16 when compared to MIS 12. 
Here we present direct land-sea- comparison (including pollen, alkenone derived SST, % C37:4 and benthic 18O) of IODP Site U1385 (Expedition 339), SW Iberian margin, covering MIS 16, TVII, MIS 12 and partially TV. Both glacials are marked by 3 main episodes of semi-desert plants expansion (dry) intercalated by two episodes of heathland expansion (wet). Although these hydroclimate changes are mainly controlled by precession, the distribution of moisture in the north Atlantic region, including the western Iberian Peninsula and northern Hemisphere ice sheets is completely dependent on the position and intensity of both the Arctic front and polar jet stream. The comparison of Site U1385 Sea Surface Temperatures (SST) with other available North Atlantic records allows us to infer the position and intensity of the Jet Stream in each processional cycle. Furthermore, the driest Iberian Peninsula phases within MIS 16 and MIS 12 seem to have been amplified by pulses of meltwater from the Eurasian ice sheets as previously demonstrated for the last glacial period.