Collaborative Research: Spatio-temporal changes in Red Sea surface hydrology and controls on deep ocean circulation since the 1700s

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Understanding the variability and long-term trends in hydrography of the Indian Ocean and connected seas (e.g., Red Sea) has implications for predicting the impacts of changes in climate across the region. Red Sea ocean circulation is vital for Indian Ocean circulation and ecosystems. This circulation supplies oxygen to critical marine ecosystems within the Arabian Sea. Evaporation within the Red Sea also plays a fundamental role in the regional hydrologic cycle and freshwater balance. These are critical for the largely agrarian societies in the region. Yet, little is known about how Red Sea ocean circulation varies across years and decades in response to changes in climate. This project will generate four records of past climate and ocean changes using corals from across the eastern edge of the Red Sea. Chemical analyses of the cores will be compared with existing instrumental data to generate records of temperature, salinity and density that extend back 200-400 years. These climate and ocean records will provide insight into how Red Sea circulation patterns change across space and time in response to climate systems. This project will support two early career female scientists. The project will also support the next generation of graduate and undergraduate scientists. These students will receive mentoring and training in marine geochemistry and paleoclimate research. In addition, the PIs will participate in art-science outreach initiatives such as Synergy II. This includes exhibitions to showcase the potential for combining geochemistry and paleoclimate to understand past variability and future threats to vulnerable societies. This project will reconstruct Red Sea surface hydrography using comparisons of multi-century coral proxy records to examine the role of spatio-temporal climate variability in preconditioning the surface ocean for deep water formation. Specifically, the study will use measurements of δ18O and Sr/Ca in coral skeleton to reconstruct seasonal to multi-decadal variability in Red Sea sea surface salinity and temperature over the past 300 years. Links between the precursors for Red Sea deep ventilation in the north and broader surface ocean hydrography will be evaluated using comparisons of coral records spanning 6º of latitude. These records will test the hypothesis that variability in salinity of northward-flowing Red Sea surface currents serves as an indicator for the strength of deep ventilation. Linkages between the spatio-temporal perspective of surface ocean precursors for deep water ventilation and regional atmospheric and climate phenomena (Arctic Oscillation, AO; North Atlantic Oscillation, NAO) will be examined, utilizing observations and instrumental climate indices. These records of Red Sea variability will identify the surface controls of deep ocean circulation and constrain variability during periods of sustained warm/cold climate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.