This research project addresses a scientific issue that is of first-order importance, deglacial ocean ventilation rates. Ocean ventilation rates describe the time elapsed since a water mass last 'saw' the atmosphere. This age information is important because ocean ventilation rates are intimately linked to climate change through the formation of deep waters at high latitudes. Most of the carbon in the coupled ocean-atmosphere system is located in the deep ocean, which exerts an important influence on climate via the greenhouse gas connection. Small changes in the rate of deep water formation are likely to have a large impact on the atmospheric carbon budget. Geochemical analyses of marine sediments cores show that many such changes in ocean circulation have happened in the geological past. The most recent large amplitude changes occurred during the last deglaciation (~20 to 10 thousand years ago), a time when the large ice sheets in North America and Northern Europe were retreating. Measurements of the radiocarbon content of deep-sea corals indicate that during the last deglaciation, the ocean was flipping back and forth between different modes of operation (i.e., different water mass distributions and different flow rates). However, it is impossible to convert the radiocarbon contents of water mass masses directly into ventilation rates, if we do not know the mixing proportions of water masses derived from high northern and southern latitude sources. This hurdle can be overcome by measuring the neodymium (Nd) isotopic composition in deep-sea corals from the western North Atlantic Ocean. Deep-sea corals are reliable recorders of the Nd isotopic composition of the water mass in which they grow. The Nd isotopic composition of the water mass in turn, is closely tied to the age of the continents in its formation area, leading to very different Nd isotopic signatures for high northern versus southern latitude waters in the Atlantic Ocean. These distinct signatures enable us to 'un-mix' the composition of waters in the western North Atlantic during abrupt climate events of the last deglaciation. Applying this knowledge of water mass mixtures to the existing radiocarbon data set on the same, absolutely dated samples, we can unravel how rapid and from where ventilation of the Atlantic Ocean occurred during the last deglaciation. Information such as this has not been obtained before, and has the potential to revolutionise our understanding of the ocean's role in rapid climate change.

Sediment deposited in deep water on continental margins is eroded from the adjacent landmasses and thus represents a record of the tectonic and climate history of that region. Decoding this sedimentary record is however not simple because a grain of sand eroded from the peaks of the Himalayas has a long and complex pathway to its eventual resting place in the Indian Ocean. Nonetheless, the rewards for understanding this sediment record are great, as they often provide the only evidence of how mountains now long eroded behaved. This is especially important in South Asia where it has been suggested that uplift of mountains, and especially the Tibetan Plateau, after the India-Asia collision has caused major climate changes, most notably the intensification of the Asian monsoon. However, proving the link between climate and tectonism has not yet been possible, though the sediments delivered to the sea by the Indus River likely hold out the best hope of reconstructing the series of tectonic and climate events that lead to the present day situation. Given that the monsoon now sustains 66% of mankind understanding its causes must be a high scientific priority. In this project scientists who have previously been working on the river and delta systems of the Indus onshore in Pakistan now propose to follow the sediment transport offshore across the shelf. Initial studies of shelf sediment show that this may not be derived from the river at all, but could be transported along the coast from the west. If so, where does the sediment in the river go to? Comparisons of 19th century and more recent charts, as well as generations of satellite images, show that the delta has been building out towards the top of the deep submarine canyon that supplies sediment into the deep sea. Does the sediment in the river bypass the shelf and run straight into the canyon? This seems hard to imagine when the coast was initially drowned by rising sea level caused by the end of the last ice age. Rising sea level would result in sediment being captured close to the mouth and an end to sedimentation in deep water. In this project we propose to map out where sediment has been accumulating in the recent past in order to see where sediment reaching the ocean from the Indus has been deposited, how quickly the deep sea started to receive sediment again after sea-level rise, and whether the types of sediment delivered to the deep sea changed with climate during deglaciation. If there was a long time gap in sedimentation in the deep sea caused by sea-level and climate change then this will affect how much erosion history we can reconstruct from those sediments. We shall survey the inner Pakistan Shelf, landward of previous surveys, with special attention to the region between the delta and the top of the Indus Canyon. We shall use seismic reflection methods to map out sediment bodies and see how the delta began to build out to the top of the canyon after initial drowning. We shall use two styles of seismic survey, one providing a very detailed, but shallow record, and one providing greater penetration into the seafloor but with less detail. Coring of the sediments in eight chosen locations will allow the age of the sediment to be determined by carbon dating of shell debris and other organic material or through the analysis of radioactive 210Pb. Furthermore, the sands and clays can be analyzed for Nd isotopes to constrain their sources (i.e., from the Indus or along the Makran coast), noting if this changes over short time spans and whether changes on the shelf correspond to those known from the delta. X-Ray analysis of clay minerals will be used to record changes in the nature of weathering in the sediment source regions, which can be matched to the known history of the monsoon at this time. Particle size analysis will be performed on a selection of 200 samples in order to constrain the depositional processes and the power of the currents active on the shelf.

The Atlantis Massif Oceanic Core Complex (OCC) is one of the best studied locations in the ocean crust, the site of four IODP expeditions so far (304, 305, 340T and 357). It is the site of the very important Lost City Hydrothermal Field (LCHF), venting alkaline fluids rich in hydrogen and methane at 40-90 centigrade. the LCHF has been suggested as an environment where Life may first have evolved on the early Earth > 3 billion year ago. Similar alkaline vents in serpentinising rocks are thought to occur on icy worlds in the Solar System such as Enceladus. Hydrogen, methane, alkanes and organic acids have all been found in the Lost City fluids, and amino acids of probably abiotic origin in previous drill core from the Massif. Our new IODP Expedition 399, sailing in April to June 2023, will seek to understand how these "building blocks of life" can be produced abiotically by interaction of seawater with rocks in the subsurface, and also the conditions under which "extremophile" microbial communities living at high T and high pH can be established and flourish. IODP Hole U1309D, located 5km north of the LCHF, is the deepest (1415m) hole so far drilled in young (<2 Ma) ocean crust; This hole will be deepened in Exp. 399 to depths of 2050 metres below seafloor, and temperatures of around 220 C, inoodre to sample rocks that have never been below the known temperature limit for life, and to study igneous processes of crustal acretion at mid-ocean ridges. However this is not the main target of our proposal here. Instead we will collect new samples from the 100m thick detachment fault zone which caps the Atlantis Massif, which is known to contain zones of reaction permeability, where minerals have been dissolved away by high temperature reactive fluids, and then the fluid filled pore spaces that result filled in by secondary minerals at much lower temperatures, within the limits of life. Other scientists on the Expedition will study microbes that may be trapped in this porosity, and the pore fluid chemistry that may have helped them to grow. We will characterise the same porosity by state of the art techniques of Scanning Electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and computerised X-ray Tomography (XCT). This last technique is the same as the CAT-scan used in medicine, but targeted at a micro scale. We will be able to quantify the porosity and also work out how large it was before it was partially filled by secondary minerals. Reaction porosity and permeability is thought to be important in the formation of some types of ore deposits, and also may be formed in geothermal energy projects, for example in Iceland. the creation and filling in porosity is also important both in petroleum engineering, and in sequestration of carbon in reservoir rocks and perhaps in reactive igneous rocks such as those in the Atlantis Massif. Hence there may be applications of our work both in the search for rare minerals, in renewable energy, and in carbon capture underground all key objectives of geoscience in the aim for net-zero. Not to mention the origin of Life on Earth!

To date, studies that have addressed the impacts of global changes have mainly focused on linking climate variability and/or human disturbances to individual life history traits, population dynamics or distribution. However, individual behavior and plasticity mediate these responses. The goal of this project is to understand mechanisms linking environmental changes (climate & fisheries) - behavioral personality type - plasticity in foraging behaviors - life history traits - population dynamics for a seabird breeding in the southern ocean: the wandering albatross. This project will also forecast the population structure and growth rate using the most detailed mechanistic model to date for any wild species incorporating behaviors in an eco-evolutionary context. Specifically, the investigators will (1) characterize the life history strategies along the shy-bold continuum of personalities and across environmental conditions; (2) understand the link between phenotypic plasticity in foraging effort and personality; (3) characterize the heritability of personality and foraging behaviors; (4) develop a stochastic eco-evolutionary model to understand and forecast the distribution of bold and shy individuals within the population and the resulting effect on population growth rate in a changing environment by integrating processes from goals 1, 2 and 3. To date, this has been hampered by the lack of long-term data on personality and life histories in any long-lived species in the wild. For the first time ever, we have tested in a controlled environment the response to a novel situation for ~1800 individuals for more than a decade to define individual personality variation along the shy-bold continuum that we can relate to the life history traits over the entire species life cycle using unique long-term individual mark-recapture data sets for this iconic polar species. The novelty of this project thus lies in the combination of personality, foraging and demographic data to understand and forecast population responses to global change using state-of-the-art statistical analysis and eco-evolutionary modeling approaches.

This proposal is to study the role of turbulent mixing in the meridional overturning circulation of the Southern Ocean and the dynamics of the Antarctic Circumpolar Current (ACC). The project is motivated by the recent discovery of Southern Ocean regions of remarkably intense and widespread turbulence, an observation that defies current theoretical understanding of the circulation based on the assumption of little mixing in the ocean interior. The project is exciting because it will use innovative instrumentation to measure turbulent mixing in the deep Southern Ocean for the first time, to determine its causes and to assess its impact on the overturning circulation and the transport of the ACC. The focus of the project will be on observing and modelling the circulation and mixing in a standing meander of the ACC north of the Kerguelen Plateau, a dynamically important region of the current system. This novel way of looking at the ACC will provide important new insight into how the the current interacts with bottom topography (a crucial issue for understanding what sets the ACC transport), the dynamical nature of the overturning circulation of the Southern Ocean and how this should be represented in ocean circulation and climate models.