Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Organic‐rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence,recording deep‐sea anoxic events. The timing of sapropel deposition coincides with precession minima,which are associated with the northward migration of the monsoon rain belt over North Africa. Theresultant increase in monsoon precipitation over the Sahara caused an increase in low‐δ18O freshwaterrunoff into eastern Mediterranean surface waters, which is reflected by negativeδ18O anomalies in therecords of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitudeof monsoon intensification and freshwater runoff, along with its influence onδ18O, remains elusive. Here,we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for theperiod of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of theMediterranean Sea, which represents different water masses, and has been calibrated usingδ18O fromplanktic foraminiferal species of different depth and seasonal habitats. The model was constrained withexisting records of sea level and sea surface temperature then inverted to deconvolve theδ18O signal of thesurface‐dwelling foraminiferal speciesGlobigerinoides ruber(w) and calculate the freshwater runoff volume.Our calculated African monsoon runoff suggests large increases in freshwater discharge to the easternMediterranean (up to ~8.8 times the modern pre‐Aswan Nile discharge). Rapid onset of S5 depositionfollowing the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterraneanfor sapropel deposition. Our study also provides insight into the stratification and warming of easternMediterranean surface waters during the S5 interval.This work was supported by Australian Research Council (ARC) Australian Laureate Fellowship FL120100050 (E. J. R.) and Discovery Early Career Researcher Award DE190100042 (K. M. G.). G. M. acknowledges support from the University of Vigo program to attract excellent research talent and a generous start‐up package

Quantification of african monsoon runoff during last interglacial sapropel S5

Organic‐rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence, recording deep‐sea anoxic events. The timing of sapropel deposition coincides with precession minima, which are associated with the northward migration of the monsoon rain belt over North Africa. The resultant increase in monsoon precipitation over the Sahara caused an increase in low‐δ 18 O freshwater runoff into eastern Mediterranean surface waters, which is reflected by negative δ 18 O anomalies in the records of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitude of monsoon intensification and freshwater runoff, along with its influence on δ 18 O, remains elusive. Here, we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for the period of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of the Mediterranean Sea, which represents different water masses, and has been calibrated using δ 18 O from planktic foraminiferal species of different depth and seasonal habitats. The model was constrained with existing records of sea level and sea surface temperature then inverted to deconvolve the δ 18 O signal of the surface‐dwelling foraminiferal species Globigerinoides ruber (w) and calculate the freshwater runoff volume. Our calculated African monsoon runoff suggests large increases in freshwater discharge to the eastern Mediterranean (up to ~8.8 times the modern pre‐Aswan Nile discharge). Rapid onset of S5 deposition following the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterranean for sapropel deposition. Our study also provides insight into the stratification and warming of eastern Mediterranean surface waters during the S5 interval.Australian Research Council | Ref. FL120100050Australian Research Council | Ref. DE190100042Australia-New Zealand IODP Consortium | Ref. LE140100047Australia-New Zealand IODP Consortium | Ref. LE16010006

The value-add of tailored seasonal forecast information for industry decision-making

There is a growing need for more systematic, robust and comprehensive in-formation on the value-add of climate services from both the demand and supply sides. There is a shortage of published value-add assessments which focus on the decision-making context, involve participatory or co-evaluation approaches, avoid over-simplification and address both the quantitative (e.g. economic) and qualitative (e.g. social) value of climate services. The twelve case studies which formed the basis of the European Union-funded SECLI-FIRM project were co-designed by industrial and research partners in order to address these gaps, focusing on the use of tailored sub-seasonal and seasonal forecasts in the energy and water industries. For eight of these case studies it was pos-sible to apply quantitative economic valuation methods: econometric modelling was used for five case studies while three case studies used both cost-loss (relative economic value) analysis and avoided costs. The case studies illustrate the challenges in attempting to produce quantitative estimates of the economic value add of these forecasts. At the same time, many of them highlight how practical value for users – transcending the actual economic value – can be enhanced, for example, through the provision of climate services as an exten-sion to their current use of weather forecasts and with the visualisation tailored towards the user

Deconvolving eastern Mediterranean planktic foraminiferal δ18O; a focus on sapropels and sea-level reconstruction

Marine sediments from the Mediterranean Sea are ideal climatic archives. The semi-enclosed geography of the basin allows the climatic signals recorded in the sediments to be amplified, and high sedimentation rates enable high-temporal resolution of climatic reconstructions. These advantages have been exploited to develop a methodology to reconstruct sea level changes, a key parameter to understanding past climates. The Mediterranean sea-level method used a planktic foraminiferal stable oxygen isotope (δ18O) record to deliver the first millennially resolved sea-level reconstruction extending beyond 0.5 Myr, which is independent from deep-sea benthic δ18O. However, there are two main issues with the Mediterranean sea-level reconstruction, which I will address in this thesis. First, the Mediterranean’s sedimentary record is punctuated by sapropels: periodic deep-sea anoxic events strongly associated with times of African monsoon intensification. The increased freshwater influx to the basin during sapropels decreases the δ18O of surface waters, creating anomalies in foraminiferal δ18O records which prevent sea-level reconstruction over these intervals. Despite extensive research on sapropels, the magnitude of monsoonal intensification and freshwater runoff, along with its influence on δ18O, remains elusive. To address this issue, I first present a suite of new palaeoenvironmental records from eastern Mediterranean sediment core ODP 967 for 1.4 to 0.6 Ma. The expression of sapropels deposited during different climatic conditions in a range of proxy records is used to characterise different ‘types’ of sapropel. Following this, a multi-site, multi-species dataset of planktic foraminiferal δ18O was compiled for a case study of last interglacial sapropel S5 (~128-121 ka). To quantitatively investigate the spatial variations in foraminiferal δ18O observed for the surface layers during S5, I develop a box model of the Mediterranean which is used in conjunction with the S5 dataset. This approach reveals the importance of surface stratification and a temperature concentration effect in producing light surface water δ18O anomalies during S5. The Mediterranean box model is then used to deconvolve the planktic δ18O signal, and to estimate the volume of African monsoonal runoff during S5. This is the first quantification of monsoonal freshwater runoff during a sapropel event. This method has potential to be applied to other sapropels, and ultimately help continue the Mediterranean sea-level reconstruction through sapropel intervals. Second, the Mediterranean sea-level method assumes a linear relationship between sea surface temperature (SST) and global ice-volume through time. However, recent Mediterranean SST reconstructions for the past 3.5 Myr suggest that this assumption may not be valid. To tackle this issue, I use the available Mediterranean SST records to approximate changes in SST response to global ice volume for the past 2.6 Myr. This is then applied to recalculate the Mediterranean sea-level reconstruction. The new Mediterranean sea-level record has a lower mean sea level than the original, and is in better agreement with deep-sea benthic δ18O based sea-level reconstructions, in particular for interglacials. This work advances our understanding of monsoonal freshwater inputs into the Mediterranean during a prominent sapropel event, and has improved the Mediterranean sea-level method to better constrain the sea-level record for the last 2.6 Myr

Eastern Mediterranean multi-species planktic foraminifera stable isotope measurements for ODP Hole 160-967B and Calypso Core MD81-LC21 for sapropel S5

This data file comprises multi-species stable isotope data for eastern Mediterranean cores ODP 967 and LC21 for sapropel S5. In addition to previously published data this makes up the eastern Mediterranean S5 multi-species stable isotope dataset discussed in the manuscript

Quantification of African monsoon runoff during last interglacial sapropel S5

Organic-rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence, recording deep-sea anoxic events. The timing of sapropel deposition coincides with precession minima, which are associated with the northward migration of the monsoon rain belt over North Africa. The resultant increase in monsoon precipitation over the Sahara caused an increase in low-δ18O freshwater runoff into eastern Mediterranean surface waters, which is reflected by negative δ18O anomalies in the records of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitude of monsoon intensification and freshwater runoff, along with its influence on δ18O, remains elusive. Here, we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for the period of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of the Mediterranean Sea, which represents different water masses, and has been calibrated using δ18O from planktic foraminiferal species of different depth and seasonal habitats. The model was constrained with existing records of sea level and sea surface temperature then inverted to deconvolve the δ18O signal of the surface-dwelling foraminiferal species Globigerinoides ruber (w) and calculate the freshwater runoff volume. Our calculated African monsoon runoff suggests large increases in freshwater discharge to the eastern Mediterranean (up to ~8.8 times the modern pre-Aswan Nile discharge). Rapid onset of S5 deposition following the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterranean for sapropel deposition. Our study also provides insight into the stratification and warming of eastern Mediterranean surface waters during the S5 interval.</p

Plio-Pleistocene planktonic foraminifer Globigerinoides ruber stable oxygen and carbon isotopes from ODP Site 967, Eastern Mediterranean

Here we present stable carbon and oxygen isotope data of the surface-dwelling planktonic foraminifer Globigerinoides ruber (white), sensu stricto, from ODP site 967. The records span the last 5 million years at high sampling resolution (typically every 1-3 cm downcore). Stable isotopes were measured using a Thermo Fisher Scientific Delta Advantage mass spectrometer coupled to a Kiel IV carbonate device

Plio-Pleistocene environmental magnetic data from ODP Site 967, Eastern Mediterranean

Here we present a bulk sediment isothermal remanence magnetism record (“IRM900@120mT”) from ODP site 967, measured using a 2-G Enterprises cryogenic magnetometer. The IRM900@120mT proxy represents isothermal remanence magnetism after imparting a 900 mT induction in a direct current field, followed by alternating field (AF) demagnetization in a peak 120 mT field. The record spans the last 5 million years at high sampling resolution (every 1 cm downcore)