In 2021, the first full inventory of emperor penguin colonies in Antarctica was generated using satellite imagery. It is therefore not surprising that their population vulnerability to changing climate is not yet well known, with colony movements only having been observed at a small number of sites. As Antarctica responds to warming climate and ocean conditions, sea ice is likely to decline, presenting a potentially significant risk to the viability of emperor penguin colonies because they live on sea ice and rely on its stability for breeding and feeding. The extent of sea ice fell by over 2 million km2 compared to average around Antarctica between 2016 and 2018, and reductions of future sea ice loss suggest that the majority of colonies may become quasi-extinct by 2100 under current greenhouse gas emission scenarios. However, both historic and future colony responses are poorly known. For example, the models which predict future behaviour are based upon breeding factors measured at a single site and behavioural factors measured at only 9 sites over a short time period of 13 years. Thus there is a significant need to improve our understanding of past colony changes and how they link to changing sea ice habitat conditions so that we can better predict future colony vulnerability under a changing climate. Although sea ice loss (and thus emperor penguin habitat) is controlled on a large scale by warming climate and oceans, an additionally overlooked process which may be increasingly disrupting sea ice conditions is the calving of icebergs which can push, or cause the fracturing of, sea ice, leaving an embayment sea ice free. In response to the loss of sea ice, emperor penguins may move to another region where sea ice conditions are more stable, or if no such area is available, they have more recently been observed to climb onto the glaciers themselves. This is a dramatic response, but without it the colony may cease to exist. Such observations of movement are again limited to a few local studies, and the impact of calving-induced sea ice breakout events upon emperor penguin colonies has never been measured. Our aim is to understand the past, present and future vulnerability of emperor penguin colonies to changing glacier and sea ice conditions. We will use existing archives of freely-available satellite imagery to map past colony movements, sea ice and glacier calving conditions at each of the 61 newly identified emperor penguin colonies in Antarctica. This will allow us to establish how historic sea ice conditions have changed at each colony and will also allow us to understand the impact of specific glacier calving events over the last 30-40 years. Our work will allow us to determine whether colony ability to move onto glacier ice or to migrate to new sea ice areas is a common reaction to sea ice loss, or whether this is a new phenomena. Using this information, we will gain better understanding of colony vulnerability to sea ice changes. In areas where colonies currently appear at risk, we will use very high-resolution commercial satellite imagery to establish whether they remain viable as a breeding colony. This understanding will be used to control and enhance numerical models of penguin population dynamics and breeding success under future scenarios of sea ice and glacier calving conditions. In particular, as air temperatures warm or as glaciers calve at a particular frequency, we will test how colonies will respond. The outcome of this work is vitally important for our understanding of the species and its survival over the next century and it expected to form the foundation for a case to establish emperor penguins as a protected species in the face of climate change.

Atmospheric nitric acid (HNO3) is mostly known for its contribution to acid rain and the associated negative effects on plants, soils and buildings. HNO3 is the end-product of atmospheric nitrogen oxidation, but relatively stable itself. Therefore, it is only lost by wet or dry deposition (precipitation or direct transfer to the Earth's surface). HNO3 gas can be converted to or adsorbed onto particles (aerosol) before deposition, which often involves splitting HNO3 into H+ and nitrate ions. Here, we only consider the sum of nitrate species, i.e., gaseous and particulate HNO3 plus particulate nitrate. The precursors to atmospheric nitrate are nitrogen oxides (NOx = NO + NO2). NOx levels are rising on a global scale, due to fossil fuel combustion, biomass burning and aircraft emissions. Higher NOx levels lead to increased nitrate deposition. Even though nitrate is an important plant nutrient, too much of it can cause algal blooms in rivers, lakes and coastal areas. Atmospheric nitrate deposition also contributes to ground water pollution by nitrate fertilisers, which can lead to toxic levels of nitrate in drinking water (causing, e.g., 'blue baby syndrome'). To understand the impacts of human perturbations of the nitrogen cycle, it is important to establish the rate of natural NOx production from soils and lightning. Unfortunately, there is nothing to distinguish natural and anthropogenic NOx sources chemically. However, the stable isotope composition of trace gases and aerosols can provide unique information on their origin and fate in chemical and biological processes. Isotopes are different species of the same element, which react in the same way chemically, but at slightly different speeds. In addition, changes in the 'isotopic signature' of a compound help tracing its way in nature. One of the goals of the present study is to establish the isotopic signature of nitrate dominated by natural NOx sources. We therefore chose to analyse a set of aerosol samples from ships across the North and South Atlantic. The contribution of anthropogenic NOx is large in the Northern hemisphere, but the isotopic composition of aerosol in the remote South Atlantic should reveal the signature of natural NOx. Also, NOx production in the tropical Atlantic is dominated by lightning. There are different pathways of HNO3 formation in the atmosphere, and whereas the source of NOx is encoded in the nitrogen isotopes of nitrate, the relative importance of these pathways (albeit not the absolute magnitudes) can be studied using the oxygen isotopes. NOx inherits an isotopic anomaly from ozone. Depending on the pathways of HNO3 formation, this anomaly is expressed to various degrees in ozone. Different pathways dominate during day and night and we hope to find evidence of their relative contributions in diurnal studies at a polluted coastal site in North Norfolk. We also hypothesise that the isotopic signature of nitrate will help us distinguish between different explanations for the diurnal cycle of nitrate concentrations. Prior to the measurements outlined above, we have to build a suitable method for isotopic analysis of atmospheric nitrate. For these analyses, a specific kind of mass spectrometer is used that can only take gaseous samples. We therefore have to convert nitrate into a gas. The direct conversion to the elements is difficult. Instead we plan to use a bacterial strain that can convert nitrate to laughing gas (N2O). It does this much more efficiently than any chemical method. JK has learnt to use this method in the lab at Princeton University (USA) that is renowned for first adapting it to environmental samples. JK has further developed it to analyse the oxygen isotope anomaly of nitrate. He plans to use this method at a later stage for direct studies of nitrate formation reactions and, possibly, nitrate in old snow samples and polar ice cores, as a constraint on pre-industrial and glacial atmospheric chemistry.

Volatile elements (hydrogen, carbon, nitrogen) played an essential role in the secular evolution of the solid Earth and the eventual emergence of life. Over Earth history, volatiles - including "trace volatiles" such as noble gases - have been transported between Earth's surface, crust, and mantle reservoirs, via subduction and volcanism. Continental cratons are relatively stable and potentially represent a large, yet poorly-constrained volatile reservoir (e.g., Sherwood Lollar et al., 2014). When cratons are disrupted by major volcanic and/or rifting events, they release large amounts of volatiles into Earth's crust and atmosphere. Such events also release economically important gases (e.g., helium and H2), which have long been stored in the stable craton (e.g., Ballentine and Burnard 2002; Lowenstern et al., 2014). The objective of this proposal is to determine the geological processes that control volatile production in the craton, migration through the crust and release at the surface in the form of seeps.

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.

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.