Paleoclimatic Changes recorded in Deep-Sea Sediments Antje Voelker Laboratorio Nacional de Energia e Geologia (LNEG) & CIMAR L.A. Delegate to ECORD Science Support and Advisory Committee (ESSAC) of IODP

Major Research Topics Changes in the thermohaline or meridional overturning circulation (MOC) and their impact on productivity => positions of hydrographic fronts; depth/ strength of MOC Proxy Calibration + Sea Surface Temperature: microfossils, biomarkers, Mg/ Ca (e.g. posters by Rodrigues et al.; Salgueiro et al.) + Productivity: microfossils, Sr/ Ca in coccoliths + Nutrient levels: trace element ratios (poster by Salgueiro et al.) + Land – ocean linkages: pollen, terrestrial biomarker (e.g. posters by Naughton et al.; Santos et al.) + Salinity: freshwater diatoms (e.g. poster by Lopes et al.) + Overturning strength: Pa/ Th -> not yet done in Portugal + Proxies for subsurface and intermediate depth water masses -> in progress Abrupt/ rapid climate change => high resolution climate series; multi-proxy reconstructions

Interhemispheric Linkages Core MD off Sines (Shackleton et al., 2000) Under glacial climate conditions: the surface ocean off Iberia reflects northern hemisphere variations and the deep ocean (>2500 m) southern hemisphere variations

Sea Surface Temperature Changes Antarctica MD & MD MD MD south of the Azores (37°N 32°W) (Martrat et al., 2007) (Jouzel et al., 2007) (Calvo et al., 2001) (Rodrigues et al., 2010) (Rodrigues et al., submitted) SST recorded millennial- and orbital-scale changes The Portuguese margin experienced more variability than the waters near the Azores due to stronger impact of subpolar waters.

Thermocline Temperature Changes FCT project INTER-TRACE IODP Site U1313 Open North Atlantic MD Upwelling off Portugal More nutrients During warm climate periods thermocline temperatures were similar at both sites. But open ocean IODP site U1313 experienced higher variability in temperature and nutrient levels.

Deep Water Circulation Changes AABW MD m Eastern Basin IODP Site U m Western Basin MIS 12 FCT project PORTO During warm climate phases NADW with similar properties filled both basins Under cold climate conditions overturning was reduced and AABW bathed both sites; BUT during glacial MIS 12 the eastern basin was better ventilated. NADW AABW NADW (Curry & Oppo, 2005) At Present NADW/ AABW boundary at 4000 – 4500m years ago NADW/ AABW boundary at 2500 – 3000m MOC reduced by 30% (McManus et al., 2004)

Mediterranean Outflow (MOW) Variability Flow velocity of Lower MOW core strengthened during ice-rafting and cold climate events (Voelker et al., 2006; EPSL) FCT project MOWFADRI Millennial-scale changes in the Gulf of Cadiz MD MD During cold climate periods MOW settled >400 m deeper in the water column Orbital- and millennial-scale changes on the Estremadura Spur (1895 m) FCT projects PORTO and INTER-TRACE MOW NADW

Impacts on Productivity: The Upwelling System 43.2°N 40.6°N 37.8°N (Salgueiro et al., 2010; QSR) FCT project INGMAR Breakdown of productivity during ice-rafting events Breakdown of productivity during ice-rafting events and higher glacial productivity Greenland Higher glacial productivity and sometimes also during ice-rafting events

Impacts on Productivity: The Open Ocean (Nave et al., in prep.) ESF (FCT) EuroMARC project AMOCINT NADW AABW Higher productivity during cold climate periods when overturning circulation was reduced

Potential Future Research IODP Exp. GUCADRILL (proposal #644 & 763 APL) with RV Joides Resolution planned to be drilled in Nov to Jan IODP Exp. GUCADRILL (proposal #644 & 763 APL) with RV Joides Resolution planned to be drilled in Nov to Jan D. Hodell (UK) & F. Abrantes (PT) proposal submitted since April 2010

Potential Future Research: Variability in the Azores Front position and impacts on Iberian margin hydrography Problem: Shiptime!!! and access to equipment for long (> 10m) core recovery! Proposal submitted to Eurofleets call

Future Needs Proxy calibration, e.g. for subsurface water masses and MOW More information on the role of subsurface and intermediate (MOW) water masses in abrupt climate change (start and recovery) Impacts of climate variability on human societies For better international competitiveness: + Laboratory facilities + Shiptime! Shiptime! Shiptime! + Education in integrated oceanography The role and position of the Azores Front in abrupt climate change