Over the last 200 years human activity has increased CO2 in the atmosphere by around 40%, roughly 25% of which has been absorbed by the oceans. This has increased oceanic acidity by around 30%. Many studies have shown negative effects of lowered pH on biological functions in a wide range of marine animals and algae. There is widespread concern from scientists, policymakers and conservationists over the effects this change is having, and will increasingly have, on marine life and on the stability of marine ecosystems. This is especially so for species with high requirements for CaCO3 to make skeletons (Royal Society 2005, IPCC 2007). There is thus a need to understand better how marine species can cope with lowered pH, how those currently living in environments of different pH are adapted to those conditions, and how these groups have coped with varying pH in the past both since industrialisation and in deeper geological time. The best way to address questions of this type is to study a marine group that is heavily calcified, has widespread distributions in sites of different pH and has a long and well represented fossil record. In this respect living articulated brachiopods are, if not the best candidate group, then certainly one of the best. They inhabit all of the world's oceans from the poles to the tropics, and from the deep sea to the intertidal. They are possibly the most calcium carbonate dependent on Earth. Over 90% of their dry mass (in some species over 97%) is accounted for by calcareous skeleton. They also have one of the best fossil records in terms of representation and abundance over long geological periods of any marine animal group. There are excellent museum collections for this group, including repeat samples of the same species over the last 150 years and extensive collections at the family level for several major geological periods from single sites. They are, therefore ideal for investigating questions associated with changing environmental pH. We will use up to date SEM and ion probe techniques to quantify articulated brachiopod skeletal characteristics (shell thickness, primary & secondary layer thickness, crystal morphology, major & minor elemental composition) to address questions in four main areas. Firstly we will investigate the effects of varying pH in current environments by sampling populations of key species living in sites of different pH. Terebratulina retusa is distributed from the Mediterranean to Svalbard, with populations living in sealochs and harbours where pH is lower than offshore. Calloria inconspicua inhabits a similar range of sites around New Zealand. We will sample populations living in different pH conditions and analyse their shells. We will also monitor pH in the areas sampled for at least a year. This will allow us to identify skeletal responses to being raised in reduced pH in the natural environment. Secondly we will quantify changes in skeletons that have occurred since the industrial revolution, when CO2 levels have been consistently rising. Both our key species have good museum collections from given localities covering the last 50 years, and T. retusa collections date back to 1870 in the BM Nat Hist. Collections of the Antarctic L. uva also date back to the 1960's. We plan to exploit these collections to identify skeletal changes over the recent past as oceanic CO2 has risen. Thirdly we will analyse shell characteristics in Articulated brachiopods from different geological periods when CO2 levels in the environment were markedly different from today. This will allow evolutionary scale responses to be addressed. Finally we will hold our key species in culture systems with altered pH conditions and assess changes in skeletal composition and structure. These approaches should provide a very good understanding of how marine species have and can respond to acidification over as wide a range of time and spatial scales as possible.

The motivation for the proposed study is the difficulty in managing water abstraction in the absence of good information about the degree of charge of aquifers, the growing consensus that groundwater recharge will diminish in arid and semiarid areas in sub-Saharan and western Africa, and the ever-increasing pressure on aquifers from increased abstraction. The aim of the proposed work is to determine the feasibility of using a NERC-developed instrument (ApRES) to aid the management of water resources in arid and semi-arid regions by allowing water-table depths to be monitored without recourse to boreholes. The challenge has both technical and societal aspects. The Autonomous phase-sensitive Radio Echo Sounder (ApRES) was jointly developed by the British Antarctic Survey and University College London to monitor the changing thickness of the floating portion of the Antarctic Ice Sheet. Lightweight, robust and relatively inexpensive, ApRES was designed to be deployed on an ice sheet for a year or more, withstanding the harsh conditions of the Antarctic winter. The problem of detecting the changing depth of the base of an ice sheet is essentially the same as that of detecting the depth of the water table in an otherwise dry environment. ApRES can therefore potentially be used as relatively inexpensive (compared with boreholes) method for monitoring the depth of the water table, providing a tool to assist in the management of water abstraction. Our choice of country for this study is Morocco. Morocco boasts a useful range of soil types, climatic conditions, and water table depths. Its many boreholes provide the necessary ground truth by offering an independent measure of the depth of the water table. A short pilot study was undertaken in Morocco in March 2017, funded through a NERC ODA Innovation pump-prime grant, and locally facilitated by the partners on the present proposal. The results were promising. Several sites were visited, with varying water table depths, primarily to find a suitable location for a multi-hour deployment. The instrument was able to detect the water table at most of the sites and was able to monitor its changing depth over a 6-hour (overnight) trial. The promising results from the pilot now prompts the next step - a comprehensive study in Morocco, alongside our Moroccan partners, to determine more precisely the envelope of capability of the instrument, and to reduce impediments to its use in monitoring groundwater depth: ease of use, robustness, cost. In the proposed study visits to different field sites in Morocco will allow the utility of ApRES to be assessed for a range of soil types, soil moisture contents, water table depths, local conditions (urban/rural) and seasons (wet/dry). The instrument and antennas will be scrutinised to see where costs can be reduced and what hardening will be needed to deal with the non-polar conditions. Finally, the data-processing steps will be rationalised such that a non-expert could carry them out. The societal aspect of the challenge, how to ensure uptake of any new technique, will be addressed in two ways. An independently resourced, but parallel study that we have instigated (to be delivered by Development i-Teams in October and November 2017) will investigate how having the ability to monitor the discharge and recharge of aquifers in real time can be used to improve the sustainability of groundwater exploitation in water-scarce regions. Second, our project partners in Morocco will prepare an implementation pathways document to define how the technology could be rolled out in Morocco. Should the project that we are proposing here confirm the technical feasibility of using ApRES for ground water monitoring in arid regions, the outcomes of the i-Teams study and the implementation pathways report will put us in a strong position to take the project forward to the next level of application, both within Morocco and beyond.

Large blooms of single celled phytoplankton which make their shells out of silica, the diatoms, are responsible for transporting the majority of carbon from the surface ocean to the deep ocean. Changes in the productivity of diatoms therefore control how much carbon dioxide resides in the atmosphere and how much is conveyed and stored in the deep ocean. The aim of this proposal is to investigate the role of diatoms in driving changing climate on long and short timescales using a characteristic and novel signature of diatom productivity, namely the d30Si. Our intention is to find out whether major changes in diatom productivity which would have enhanced the draw-down of carbon dioxide from the atmosphere to the deep ocean, during the last ~ 50 Myrs could have contributed to Earth's transition from a greenhouse world with no or little ice, to the modern ice house world with the current bipolar ice sheets. Further, we aim to build on some preliminary evidence that diatoms are flourishing with global warming and find out whether diatom productivity could act as a negative feedback on anthropogenic emissions of carbon dioxide. As glaciers retreat around Antarctica and the meltwater flux increases into this highly productive coastal zone, there is the potential for increased input of nutrients and also enhanced stability of the water column, each of which can lead to enhanced diatom productivity. We shall construct a record of diatom productivity, again using d30Si, over the last 500 years in rapidly accumulating sediments of the Antarctic Peninsula. By targeting the last 500 years, our analyses will capture the last glacial advance and recovery from the Little Ice Age period (ending 1850) of the Holocene and allow us to test whether diatoms consistently increase productivity as glaciers retreat, and assess whether the diatom response to the anthropogenically forced glacial retreat is unprecedented on this timescale.

The thermosphere is the uppermost layer of our atmosphere at the edge of space (85 to 1000 km altitude). Within this region orbit thousands of satellites worth billions of pounds that provide essential modern services including satnav, satcomms, and remote sensing. There are also many thousands more orbiting pieces of man-made space debris which present a significant risk to operational satellites because of the chance of collision. We have now passed a tipping point where the increase in debris from collisions exceeds losses, leading to a net growth of the space debris population and thus ever-increasing risk of collisions. Short- and long-term predictions of satellite and debris trajectories are vital to avoid the destruction of satellites in low-Earth orbit. A major factor limiting factor is knowing the density of the thermosphere, which can vary by up to 800% during extreme times. The variability is due to effects in near-Earth space from disturbances on the Sun, collectively called space weather. In the polar regions, where there is the greatest concentration of satellites, the largest uncertainties in thermospheric density arise from "Joule" heating. This is caused by collisions between electrically-charged and neutral particles in the thermosphere, driven by space weather. Crucially, we have yet to properly understand when and where Joule heating will occur and how predictable it is. Accurate models and prediction of Joule heating are vital to safeguard the space assets on which modern society depends. In this project we will develop a better understanding of Joule heating by analysing more than a decade of data from two major international polar instrument networks. We will use a statistical method developed in meteorology called Empirical Orthogonal Function (EOF) analysis, which is capable of uncovering the underlying patterns in a large, noisy data set. In this way we will both resolve the Joule heating in unprecedented detail and separate it into patterns which depend to greater or lesser degrees on the solar sources of space weather. Since these sources can be observed before they cause space weather at Earth, this will allow us to quantify the limits of predictability of the Joule heating. By then assessing the relationship between the Joule heating and satellite trajectories, this will allow us to describe which orbital paths are most at risk from space weather.

In response to global warming, the ice covers of the Arctic and Antarctic are changing, with a significant reduction in the summer extent of Arctic sea ice. The reduction of Arctic sea ice is more rapid and extreme than climate models predict, suggesting that these models do not adequately represent the processes controlling this reduction. The reduced summer Arctic sea ice cover, and changes to the winter sea ice cover, affect the mechanical and thermodynamic coupling between the air and ocean. In fact, observations show that the sea ice cover has become more mobile in the last 15 years and that there has been an increase in the mean ocean circulation beneath the sea ice. Since, over the same period, there has not been an observed increase in wind strength, this suggests that changes to the sea ice cover itself are responsible for an enhanced ice motion and transfer of wind stress to the ocean beneath sea ice. Our project hypothesis is: Changes in the Arctic sea ice cover have resulted in a more efficient transfer of momentum between the air and ocean, resulting in spin up of sea ice and the Arctic Ocean. We will test this hypothesis with a combination of new data, theory and numerical modelling. We will investigate how changes in the roughness of the ice cover, e.g. through a more dilute ice cover having more floe edges exposed, change the drag forces exerted by the air on the ice and the ice on the ocean. We will investigate how a reduction in the ice cover may reduce the resistance of the ice cover to the wind, allowing it to move more easily. In particular we address the question: to what extent is acceleration of the Arctic sea ice gyre the result of decreased ice forces versus increased drag? We will use climate models containing new physics calibrated with, and derived from, new observations, to examine the prediction that: Changes in the sea ice cover will continue to lead to enhanced momentum transfer between the air and ocean, resulting in a more mobile and responsive ice cover and enhanced flow and mixing in the Arctic Ocean. Although we focus our analysis on the Arctic Ocean, where sea ice changes have been more dramatic, we will also examine air-ice-ocean momentum exchanges in the Southern Ocean. This proposal brings together leading researchers in sea ice dynamics, remote sensing, ocean and climate modelling, and builds upon existing expertise in satellite observation, theory, and modelling of sea ice in the Centre for Polar Observation and Modelling. In addition to the scientific outcomes, the proposed work will result in new sea ice drag physics being incorporated into a sea ice climate model and delivered to climate modelling groups. This will directly help scientists investigating and predicting future changes to the sea ice cover in the Arctic and Southern Oceans and also help scientists trying to understand and predict changes in the global climate system.