The Arctic sea ice zone (SIZ) affects atmospheric composition and climate, and it is responding rapidly to climate change. We urgently need to quantify its influence on the regional/global atmosphere so we can predict how this may change in the future. Arctic research is logistically and scientifically challenging, and continually relies on new international partnerships, shared science expertise, data, and logistics. This scientific context and modus operandi entirely reflects our focus and approach within the proposed ABSCISSA project. Our scientific focus is the potential of the Arctic SIZ to be a source of sea salt aerosol (SSA). Aerosols are small particles in the atmosphere which play several critical roles. They affect the transmission of sunlight and the formation of clouds. They host the production of halogen compounds to the atmosphere which in turn affect atmospheric oxidation chemistry and the availability of mercury to the food chain - a major current health concern for Arctic people. When they are deposited on polar ice caps, sea salt aerosols leave a record of past conditions that can be accessed by drilling ice cores. So it's important to pinpoint and quantify sources of SSA. There is strong evidence that in the polar regions, the source is the effect of wind blowing on salty snow on the sea ice surface. If this is right, it opens the possibility of using ice core data to derive changes in sea ice extent over long time periods. It is therefore important to understand the sources of polar sea salt aerosol and to be able to predict how they may vary with, and feedback to, climate. Field work within the SIZ is challenging - the area is hard to access and very few ship-based programmes operate there, particularly during the winter. However in winter 2015, the Norwegian Polar Institute (NPI) will host a cruise on their research ship, Lance, deep within the Arctic SIZ. We have negotiated a chance to participate but need funding for the mandatory financial contribution. We have established new project partners in NPI with whom to work. Our scientific aim is to determine whether wind-blown snow on sea ice really is the dominant source of Arctic sea salt aerosol, and to make a series of measurements needed to parameterise this process in numerical models. We will use the same methodology, equipment and personnel deployed by us during a previous successful winter cruise to the Antarctic SIZ (funded by NERC), thus using previous NERC investment as a springboard for this Arctic research. The Arctic SIZ is substantially different from that of the Antarctic so to assess sea salt sources and impacts in the Arctic, we must have data derived directly from the Arctic SIZ. The collaboration with NPI is highly mutually beneficial: NPI logistics will enable access to an otherwise inaccessible region; we will make novel measurements, needed, but not made by our NPI partners; similarly, their data will fill gaps in our measurement suite; we will all contribute expertise for data interpretation. Such working practices provide considerable leverage, and build strong collaborations for the future. Strategically, the project fits within a government-level MoU that aims to increase scientific collaboration between the UK and Norway. The project fits NERC aspirations for BAS to assume an increased role in the Arctic. In the longer-term, we will use our data i) to scale up to derive an Arctic regional source, ii) to compare with sea salt production over Antarctica, iii) to assess the impact on chemical composition of the atmosphere, and iv) to assess the suitability of sea salt aerosol as a sea ice proxy. Our results thus contribute to a range of different academic groups, raise the profile and momentum of UK science within the Arctic, and contribute to an area of intense scientific, political and public interest: the socio-economic and climatic implications and feedbacks associated with reducing Arctic sea ice extent.

Antarctic Bottom Water (AABW) is an important water mass in the cooling and ventilation of the World's deep ocean. One of the principal sources of AABW has its roots in the production of cold, dense water that results from wintertime sea-ice production over the continental shelf of the southwestern Weddell Sea. However, there remains great uncertainty about the processes controlling the initial import of the source waters onto the continental shelf, and the export of the dense waters from the shelf regime. The uncertainty results from the extremely challenging sea ice conditions existing in the southern Weddell Sea, especially during winter. Conditions in the area of interest during winter are exceptionally difficult for any ship-based work, and instruments deployed in the ocean during the rather less difficult summer months, and which are left to monitor the water properties over the Winter period, are vulnerable to dredging by passing icebergs. We will tackle the problem using a technology that has recently come of age. We propose to attach conductivity-temperature-deph (CTD) tags, miniaturised oceanographic instruments, to Weddell seals (Leptonychotes weddellii). The tags have a satellite transmitter that relays the oceanographic data collected during the seals' dives, together with the dive location. The tag is glued harmlessly to the animal's fur using standard marine two-component epoxy and comes off again during the annual moult about eleven months later. A pilot study undertaken by the British Antarctic Survey involved the tagging of four seals, three of which supplied over-winter datasets. Although the coverage was impressive from only three tags, emphatically confirming the practicality of the technique, the region of interest is nearly 500,000 km^2 in area and a comprehensive dataset requires substantially more tagged animals. We will tag 20 Weddell seals at the eastern end of the shelfbreak north of the Filchner-Ronne Ice Shelf during the late Austral summer of 2010/2011. The resulting dataset resulting from the animals' dives during the winter will give the most comprehensive picture to date of the ocean conditions over the southern Weddell Sea continental shelf. By mapping the temperature of the water near the sea floor we will determine the locations where dense waters leave the shelf, and the processes involved: either a direct flow down the slope under gravity, or initially mixing at the shelf edge with waters from off the shelf before descending down the slope. We will also be able to determine where the source waters come on to the shelf. Weddell seals are very accomplished divers, diving repeatedly for long periods and to depths regularly reaching the on-shelf seafloor. Among Antarctic seals, Weddell seals also inhabit the southernmost waters, and remain within the pack-ice in winter when the ice expands northward. These characteristics make Weddell seals ideally suited for the proposed study. Although primarily an oceanographic project, the movements and diving behaviour of Weddell seals is of great interest to seal biologists who wish to understand differing behaviours in different parts of Antarctica. These variations were ably demonstrated by the extraordinarily diverse behaviour of the animals tagged during the pilot, and by comparisons with previous tracking of this species in other parts of the Antarctic. The long-ranging movements displayed by some of the seals tracked during the pilot study are untypical for the species, at least at other Antarctic locations, and may be related to the local oceanographic conditions. It is widely recognised that multidisciplinary studies such as proposed here will provide us with the tools to better predict how the distribution, behaviour and ultimately population status may be affected by changing ocean and climate conditions.

The Southern Ocean represents less than one-tenth of the area of the global ocean, yet it currently absorbs 43% of the total anthropogenic CO2 and 75% of the heat. Critically, the Southern Ocean's capacity to modulate the atmospheric CO2 concentration is governed by the strength and position of the Southern Hemisphere westerly winds. These winds drive upwelling of carbon-rich deep water, which together with sea ice coverage, determines the ocean surface area available for air-sea gas exchange. Westerly winds are predicted to increase in strength during the 21st century, as a result of anthropogenic forcing, while sea ice is predicted to decrease. The combination of stronger winds over the surface ocean and reduced sea ice cover will enhance upwelling of carbon-rich water from the deep ocean. Thus, the Southern Ocean may switch from a CO2 sink to a CO2 source, potentially releasing CO2 into the atmosphere and accelerating global warming through enhanced radiative forcing. However, our understanding of the role of westerly winds on CO2 release is limited by the short observational records with large uncertainties in the magnitude of projected westerly wind changes in climate models. In order to better constrain future predictions of CO2 emissions and climate change, we urgently require long records of atmospheric CO2, westerly winds and sea ice in the Southern Ocean. Ice cores are the only paleoclimate archive that can reconstruct all three parameters beyond the instrumental period. The aim of this proposal is to provide high resolution records of westerly winds, sea ice and atmospheric CO2 concentrations over multi-decadal to millennial timescales. We will do this by drilling a new ice core in coastal Antarctica, match funded by the National Centre for Polar and Oceanographic Research (NCPOR), Indian Ministry of Earth Science, with additional support secured from the Norwegian Polar Institute and the UK embassy in Delhi. We will conduct state-of-the-art analysis, using newly developed proxies for westerly winds based on marine diatoms. Advanced measurement of the stable isotopic composition of CO2 will take place in the newly established UK Relic Air Extraction and Gas Analysis System (UK RArE-GAS) laboratories and build on the UK's growing expertise in this field. This is an exciting opportunity for UK scientists to collaborate with leading polar research institutes in Norway and India. This tri-national partnership (India/Norway/UK) considerably increases the scientific, societal, and political impact. Disentangling the drivers of CO2 variability over seasonal to millennial scales is essential in predicting future changes in atmospheric CO2 concentrations. If the Southern Ocean switches from a CO2 sink, removing anthropogenic CO2 from the atmosphere, to a CO2 source, releasing CO2 from the deep ocean, is of global concern. Thus, we anticipate this project will have high scientific, political, and social-economic impacts. These social-economic impacts will hit some countries harder than others. India's large coastline and rapidly increasing population, many of whom live in low-lying coastal basins, make it particularly susceptible to future sea level rise. India is the fifth most vulnerable country in the world to the impacts of climate change and is under pressure to reduce its greenhouse gas emissions. Thus, this new collaboration with partners in India provides compelling potential for NERC and UK scientists to support and promote climate science in an ODA country. Working directly with the Indian Ministry of Earth Sciences and facilitated by ongoing collaborations with senior advisor for climate change and environment at the British High Commission in Delhi.

Non-technical summary Calanoid copepods are key players in World's oceans. They are the largest constituent of oceanic zooplankton biomass and are a major link within global carbon cycles. In the North Atlantic and Arctic, calanoid copepods are a vital food for commercially important fish species such as cod, mackerel and herring. A key feature of many calanoid copepod life-cycles is a phase of overwintering at great depth, in a state analogous to hibernation. This increases their chances of surviving to the next season through avoiding predation at times when there is little else to be gained by remaining within the surface layers. A notable feature of calanoid copepods is that they contain exceptionally high amounts of fat (or lipid). The large lipid store is both a valuable energy reserve and a major determinant of buoyancy. The attainment of neutral buoyancy is important to copepods over winter since they must minimise swimming effort in order to save energy. A balance must be sought between provisioning for the winter without disturbing the ability of the copepod to achieve neutral buoyancy. The best scientific efforts at trying to simulate this balance have so far proved to be unsatisfactory. Recently, two potential additional mechanisms of buoyancy control have been identified. In one study, Sartoris and colleagues found that diapausing copepods contained a different balance of ions in their bodily fluids (haemolymph) compared to active, surface dwelling copepods. In a second study, scientists involved in the present proposal showed that lipids rich in omega-3 polyunsaturated fatty acids (PUFAs) changed from liquid to solid state when under pressures typical of the deep sea. The effect only happened when PUFAs comprised more than 50% of the lipid store which, coincidentally, was commonly found in deep diapausing copepods, but not in those still active at the surface. At present, both of the mechanisms have only been identified in Southern Ocean copepods, although previously 'misinterpreted' evidence in the scientific literature also suggests that northern hemisphere species employ similar techniques. We will carry out surveys across a number of locations in the North Atlantic, Arctic and adjacent sea-lochs to determine lipid composition and haemolymph-ion concentrations in three calanoid copepod species. The surveys take into account environmental influences, particularly the type and availability of the microplanktonic food of copepods. This will determine whether there is any active regulation of the levels of omega-3 fatty acids in the lipid stores. Such active regulation may be of particular importance towards the end of winter as a means of controlling the timing and rate of ascent back into the surface layers. Our sampling strategy, application of novel analytical techniques and datasets generated during the research will allow these questions to be addressed. Secondly, using statistical techniques we will reconsider efforts made so far to simulate overwintering depth and seek improvements through including additional data and mechanisms. For instance, in changing from a liquid to solid state, the volume occupied by a lipid will be decreased and its response to increasing pressure will change. The effects of ionic balance will also be considered, mainly in how it may assist copepods maintain their theoretical neutral buoyancy depth in the face of any physical disturbance. This research proposal is based on our recent discovery, that the biophysical properties of lipids are a major factor controlling the distribution of life in the oceans. This finding gives an exciting new perspective on the role of lipids in marine organisms, opening up a fundamentally new direction for research, with profound implications for our understanding of the entire ocean food web.

Ecosystems are communities of organisms that interact with each other and their environment. They are often considered in terms of food webs or chains, which describe the interactions between different organisms and their relative hierarchies, known as trophic position. Ocean ecosystems provide key services, such as nutrition, control of climate, support of nutrient cycling and have cultural significance for certain communities. It is thus important that we understand how changes to the environment reshape ecosystems in order to manage climate change impacts. The Arctic Ocean is already being heavily impacted by climate change. It is warming faster than any other ocean region and as it absorbs fossil fuel emissions, it is gradually acidifying. Arctic sea ice is declining by 10% per decade. This affects the availability of sea ice habitats for organisms from plankton to mammals and modifies the ocean environment. Finally, the Arctic is affected by changes in the magnitude of water movement to and from the Pacific and Atlantic Oceans and composition of these waters. Thus Arctic ecosystems are being impacted by multiple concurrent stressors and must adapt. To understand how Arctic ecosystems will evolve in response to multiple stressors, it is crucial to evaluate the effects of on going change. Often these questions are tackled by studies that focus on a specific ecosystem in one location and document the various components of the food chain. However the Arctic is diverse, with a wide range of environments that are responding to unique stressors differently. We require a new approach that can provide information on Arctic ecosystems from a pan-Arctic perspective over decadal timescales. To effectively monitor changes to pan-Arctic ecosystems requires tracers that focus on key ecosystem components and provide quantitative information on ecosystem structure, providing information for management and conservation of ecosystem services. Our goal is to respond to this challenge. We will focus simultaneously on the base of the food chain, controlled by the activity of marine phytoplankton, and key Arctic predators, harp and ringed seals. Seals are excellent candidates to monitor the food web due to their pan-Arctic distribution and foraging behaviour, which means they are exposed to the changing environment. Nitrogen and carbon stable isotopes are often used to examine ecosystems as they are modified during trophic transfer up the food chain. Hence, they can quantify seal trophic position and food chain length, key determinants of ecosystem structure. Crucial in this context however is the isotope value of the base of the food web, known as the isoscape, which is itself affected by a range of environmental characteristics and fluctuates in space and time. Equally, by virtue of changing migration patterns, seals themselves may feed on similar prey in different isoscapes, which would affect the interpretation of ecosystem structure from stable isotopes. These are the major challenges in using stable isotopes. We will link stable isotopes to novel tracers of the food web, known as biomarkers. When these tracers are compared against observations of the shifting isoscape and data on seal foraging, they permit seals to be used to monitor the Arctic ecosystem by quantifying their trophic position and overall food chain length. Via a range of observational platforms, our new food web tracers will be mechanistically linked to the spatial and seasonal trends in the Arctic isoscape and seal behaviour. By then combining historical observations from around the Arctic basin with state of the art ocean and seal population modelling, we can quantify past and future changes in Arctic ecosystems. This will provide information on past changes to Arctic ecosystems, but also put in place an approach that can be used to monitor future changes and aid in the management and conservation of ecosystem services.