NOC

Sea-level change is one of the most significant threats facing society over the next 100 years and beyond. Measurements of current sea-level change have shown that there has been a mean global sea-level rise of between 10 and 20 cm over the 20th century. A further rise in sea level of between 20 and 80 cm is predicted by AD 2100 due to future global climate change. However, such predictions of future change are subject to very large uncertainties because our understanding of the past behaviour of sea level is poor. It is essential that we quantify sea-level changes in the recent past if we are to provide more accurate and precise predictions for the future. It is clear from measurements and from sea-level reconstructions based on geological data that there has been a significant increase in the rate of sea-level rise from the 19th to the 20th century. We ask the question: Have similar accelerations of sea-level rise happened in the past? Some of our published geological reconstructions give us good reason to believe that there were pre-industrial sea-level accelerations and these require further investigation. We aim to establish the precise timing and magnitude of these rapid rises of sea level by constructing detailed 500-yr histories of sea-level changes in six sites around the North Atlantic Ocean. These records will be based on the remains of fossil plants and animals buried in coastal sediments which are excellent indicators of the past level of the sea. Timing is key, so we will use the most advanced dating methods, in particular ultra-high precision radiocarbon dating techniques, to find out when the rapid increases in sea-level rise occurred. If the changes we observe occurred in various sites at the same time, then it would imply that hitherto unknown episodes of land-based polar ice melt are responsible. There are important processes that obscure the sea-level signal derived from melting ice that may be observed in coastal sediments and tide gauges. These include changes in the density of sea water - leading to expansion/contraction - due to temperature and salinity variations and vertical movements of the coast. We will correct for these processes separately, using models and available tide-gauge and ocean temperature measurements. First, we will create a model that can calculate steric (density) changes along the coast. Measurements of ocean density are available for the past 50 years, but these were taken in the open ocean, not near the coast. Many processes operating on the continental shelves, such as tides, currents and winds, mix the water column in these areas and so using ocean records may be inaccurate. Our model will help us to predict how the water density changes at the coast following a measured change in the middle of the ocean. A second model can simulate ocean steric changes for the past 500 years, a period for which ocean density and temperature data are not available. Some additional corrections for wind, air pressure and tidal changes, are also necessary but these are relatively easy to do. Second, we need to remove the effects of long-term land movements from our records. We will do this by reconstructing sea-level trends over the last 2000-3000 years and subtracting these from the proxy reconstructions. There are also geophysical models and GPS data that can help with this correction. The 'corrected' records of sea level will be analysed to determine whether synchronous episodes of sea-level rise have occurred in the past 500 years. We believe the work is important because it will, for the first time, enable us to test whether accelerations in sea-level in the North Atlantic have occurred at the same time or not, and if they have, we can determine how big they were. These data will provide important 'baseline' constraints for future sea-level predictions.

The seasonal thermocline in temperate shelf seas acts as a critical interface in the shelf sea system. It is a physical barrier to vertical exchange, controlling biological growth through the summer and enabling the sequestration of atmospheric CO2. Once the spring bloom is over the seasonal thermocline separates the sun drenched but nutrient deplete surface waters from the dark nutrient rich deep water. The vertical mixing of nutrients across the seasonal thermocline acts to couple this well-lit surface zone with the deep water nutrient supply, leading to the formation of a layer of phytoplankton within the thermocline (the subsurface chlorophyll maxima). This phenomenon is estimated to account for about half of the annual carbon fixation in seasonally stratified shelf seas, and yet the controlling physics is only just being unravelled. The identification and parameterisation of the physical processes which are responsible for the vertical mixing of nutrients across the thermocline is a vital prerequisite to our understanding of shelf sea ecosystems. Our proposal is to investigate the role of wind driven inertial oscillations in driving vertical mixing across the seasonal thermocline, identifying the mechanisms and processes responsible for their generation and dissipation on both special and temporal scales. The proposal will be achieved through an observational campaign closely integrated with numerical model predictions using both 1D and 3D numerical models.

Observations of e.g.\ ice cores and tree rings tell us that the Earth's climate system is changing all the time. With the ocean occupying over 70\% of the Earth's surface, fluctuations in the climate system are strongly affected by the ocean and its currents. One key element in the climate system is the communication between the atmosphere and ocean interior, which is what scientists called 'ventilation of the ocean interior'. Through the ventilation process, momentum, heat and gases are exchanged at the ocean surface, transferred into the ocean interior and distributed around the globe by ocean currents. The climate system is sensitive to the rates and pattern of ocean ventilation since these dictate the speed of transmission and the pathways of anomalous climate signals that travel through the ocean interior and re-appear at the surface to feedback to the atmosphere. However, what puzzles scientists at the moment is, although they know the climate change is mediated by ocean ventilation, they don't know exactly what controls the rate of ocean ventilation. Having said that, scientists do know that ocean ventilation is largely forced by buoyancy flux at the surface (the combined effect of heating from the Sun and exchange of heat and moisture with the atmosphere). If surface waters cool (or become salty) they becomes denser and then mix vertically with underlying lighter waters, bringing these deeper waters up to the surface. When the surface warms again, the lower part of this column of ventilated fluid is cutoff from the surface again and may move down into the ocean interior. However, there is a further complication by which small-scale (~ km to 100 km) features---called eddies---also affect the ventilation rate by mixing dense and light water horizontally near the surface. This is particularly important in the Southern Ocean where eddies are known to be very energetic as a result of strong westerly winds blowing over the world's largest current, the Antarctic Circumpolar Current (ACC). As these small eddies are very difficult to observe---you need many measurements covering a wide region over a long period---scientists use approximate rules (`parameterizations') that estimate the presumed effect of the eddies in terms of the large scale flow. To this date, scientists are not sure whether these parameterizations correctly predict the effect of eddies on oceean ventilation because computer models that simulate ocean eddies seem to disagree with some of these predictions. It is important to resolve this conflict because if eddies are important in controlling ventilation, then they need to be properly incorporated in the climate prediction models which cannot simulate them explicitly with the present day computer power. The goal of our study is to improve our understanding of the role of small scale processes on controlling the ventilation rate in the Southern Ocean. We will conduct a series of idealised model experiments which simulate a simple ACC system in the Southern Ocean. The advantage of using simple models is that we can isolate the effect that eddies have on the ventilation rate of the ocean from that due to seasonally and annually varying forcing. The insight gained from these experiments will tell us a great deal about how these eddies help or hinder the ventilation of the Southern Ocean. The Southern Ocean is one of the world's largest carbon sinks where carbon is taken away from the atmosphere to be locked up in the deep ocean so it does not contribute to the global warming. Any changes in the Southern Ocean that may impact on its ability to absorb carbon concern all of us in every part of world. Our study aims to improve our understanding of a key element of the Earth system which ultimately determines how nature will respond to changes wrought by human activity.

A wide range of infrastructure underpins our day-to-day lives, yet our intense reliance on these potentially vulnerable systems is often forgotten. Road and rail provide transport, pipelines carry energy and water, and cables transmit and distribute power and communications. Some of these networks are over 100 years old, while others involve brand new technology, but all of them have potential weaknesses to environmental hazards. Several recent network failures caused by such natural hazards have provided a sharp wake up call. Examples include the Dawlish railway collapse due to storms in 2014, damage to homes, bridges and roads in Cumbria in 2014/15, and flooding in Somerset leading to widespread loss of power in 2013/14. These events had profound impacts on people's lives, as well as large costs (>£Ms) to the local and UK economy. Such events may become more likely and more intense as the world continues to warm. In extreme cases, environmental hazards can have global implications. The 2010 Eyjafjallajökull eruption in Iceland, for example, caused worldwide disruptions to air traffic, yet prior to its occurrence the effects of ash on aircraft engines had not been considered a major risk. Thus, there is a need to better understand the risk posed by environmental hazards to infrastructure. This is particularly important as we experience changes in our climate, as new technology is developed, new areas are explored, and populations grow. This fellowship aims to help address this risk through identifying gaps in our knowledge and assessing how future research can fill them. Importantly, this fellowship is supported by several industry organisations that are directly involved in assessing the risk posed by natural hazards to a wide range of infrastructure. The proposed work will involve time spent with those specialists, to understand the potential impacts, lessons learned, and how ongoing and future research can make real changes and improvements to assessing environmental risk. First, the fellowship will determine whether industry has missed any key hazards, such as the Icelandic ash cloud and its impact on air travel. An inventory of potential hazards will be compiled and assessed by a joint academic and industry panel. This may include new hazards such as the breakage of subsea communication cables by underwater avalanches of sediment ('turbidity currents'). Such cables transport 99% of the world's communications including important financial data and the internet. Extreme events are difficult to predict as we have not typically experienced many (if any) since accurate records have been kept. Despite this, they can be the most damaging events. The fellowship will explore different techniques and tools for predicting and assessing extreme hazards such as developing new statistical methods that are more often used in medicine or financial studies. Such tools will need to include the effects of future climate change. Often, individual large events may not damage infrastructure, but the combined or successive effect of smaller natural hazards may be catastrophic. Here, it is proposed to summarise the lessons learned from a number of infrastructure owners, consultants and contractors to understand how we can better understand compound or cumulative impacts, and how that can inform the development of models in future. In the same way as you go to the doctor to get a health check, it is important to understand the health of infrastructure. Historically this has been done by in-person inspections, but step changes in technology now enable remote and real-time monitoring. New technologies that can be used to monitor natural hazards and their impact on infrastructure will be summarised. Groups of researchers and industry representatives will be paired up to see how we can define best practice for industry in real-time monitoring of environmental hazards and increase cost-effectiveness of such efforts.

The oceans play a major role in determining the world's climate. In part this is due to the production of oxygen and the consumption of carbon dioxide by very small, single celled organisms, which are referred to as the photosynthetic picoplankton. Marine cyanobacteria of the closely-related genera Prochlorococcus and Synechococcus are the prokaryotic components of the photosynthetic picoplankton. Current and previous work in my lab has demonstrated that the in situ community structure of these organisms is fairly complex, with specific ecotypes or lineages occupying different niches to populate the world's oceans, allowing them to grow and photosynthesise under a broad range of environmental conditions. Whilst such molecular ecological studies can effectively map the spatial distributions of specific genotypes, the factors that dictate this global community structure are still poorly defined. This is important because changes in dominant picocyanobacterial lineages indicate major domain shifts in planktonic ecosystems and by observing and interpreting their distributions and physiological states we are essentially assessing changes in the rates of biogeochemical cycles. Athough the role of macronutrients, particularly N and P has received previous attention still there is a relative dearth of data on factors controlling picocyanobacterial community composition. Certainly, little if anything is known of the role of trace metals in this process. Thus, we hypothesise that in oceanic ecosystems genetically distinct picocyanobacteria are restricted to specific niches by their ability to acquire (limitation) or regulate trace metal accumulation (toxicity). In order to address this topic we propose to investigate trace metal (and macroelement) cell quotas in i) representatives of specific marine Prochlorococcus and Synechococcus lineages and to assess the affect of light stress and macronutrient shifts on these quotas and ii) in natural picophytoplankton assemblages using prior flow cytometric sorting, ICP-MS and X-ray microanalysis techniques. In so doing we will also obtain, for the first time, a real indication of picocyanobacterial cell physiological state over large spatial scales / in effect using elemental quotas as a proxy for what environment a given cell/population of cells is experiencing in situ / and hence can realistically begin to determine those macro and trace elements that are potentially depleted in situ and which are potentially restricting growth rate and/or yield.