Omitted from the 2007 IPCC Fourth Assessment Report on Climate Change was the potential contribution from ice sheets to global sea level. This reflected the level of uncertainty with respect to the ice dynamics (motion) and mass balance (snow and ice accumulation vs. snow and ice loss) of the extant ice sheets in Greenland and Antarctica. One potential key control on ice dynamics is glacier crevassing which can facilitate the routing of surface melt water to the ice sheet bed leading to increased sliding velocities on outlet glaciers. Additionally, crevassing controls the production of icebergs at marine terminating margins, through which the Greenland Ice Sheet disposes of ~50% and the Antarctic Ice Sheet almost all of their respective annual ice loss. Iceberg production (calving) may be through a combination of both bottom-up and top-down crevassing but atmospheric warming, by increasing the availability of melt water to fill surface crevasses, is likely to be the main driver of change, in the short term at least. Only recently have advances been made in the development of physics-based crevassing/calving relationships with incorporation into predictive numerical models. These advances are vital for improving our predictions for the response of the big ice sheets to future warming. However, only one study to date has tested these physics-based crevassing relationships and then only for shallow water-free crevasses. Given the current research focus on glacier crevassing, there is an urgent need to test crevassing models. To do this in the field is however challenging, due to difficulties of working in crevasse zones of glaciers, measuring the depth of what ultimately ends in a hairline crack at depth and associating the crevasse with the instantaneous stress/strain field. Project Partner DB has a project in preparation to deploy instrumentation for continuous water level monitoring in crevasses on Kronebreen, Svalbard. Geophysical imaging is currently problematic for example signal attenuation on 'warm' temperate glaciers, signal interference from adjacent crevasses in crevasse fields and obtaining the resolution to image the crevasse (crack) tip. Likewise controlling water-depth to force crevasse penetration would present significant challenges for example, the volume of water needed for filling a crevasse or connection with the englacial drainage system leading to water loss etc. Field monitoring of glacier crevassing is thus in its infancy. A modelling approach therefore represents an ideal way forward. However, lab-floor models are useless because the stresses relevant to crevasse propagation increase as a function of both the self-weight stress (gravity x ice density x ice thickness) and crack length i.e. the crevasse depth. The geotechnical centrifuge is a unique modelling tool which allows the magnitude self weight stresses to be reproduced, with stress equivalence between the prototype (real world) and the model by scaling down the dimensions in the model but 'enhancing' gravity. This is achieved by 'flying' (spinning) the model in the centrifuge such that an Nth scale model flown at N times gravity generates the same self-weight stress as the prototype. Scaling relationships are already established for all the parameters relevant to this study so no scaling issues are anticipated, but the standard modelling of models centrifuge technique will be employed to confirm this. Then a series of models will be run, replicating the stress levels experienced in a prototype glacier section ~50x80x50 m. Pre-cast crevasses will be filled with water to facilitate step-wise full-depth crevasse penetration allowing the current state of the art physics-based models to be tested. This project will provide a proof of concept which will facilitate further grant applications where more complex models (e.g. bottom-up and top-down) can be built and used to test and develop physical models.

Diel vertical migration (DVM) by zooplankton is a prominent feature of many marine ecosystems. Animals move quickly tens to hundreds of meters vertically around dawn and dusk in migrations that comprise the most massive periodic shifts in biomass on Earth. The classical view is that DVM occurs as a trade off by individuals between food acquisition and predator avoidance. Herbivorous zooplankton move upwards to feed at night under the cover of darkness in the near-surface where primary production occurs but where the risk from visual predators is greatest. This upward/downward migration redistributes C fixed by photosynthesis near the surface to deeper waters, and may reduce the rate of atmospheric CO2 accumulation. In the open sea DVM periodicity varies with latitude and season as day length varies. The occurrence and amplitude may also vary as a function of light intensity, resulting in unusual patterns at high latitudes during continuous daylight. Sea ice cover impacts underlying waters physically (eg shading) and biologically (eg reducing photosynthesis and excluding surface diving predator) and so may impact zooplankton abundance/behaviour. However, due to major logistic difficulties associated with sampling under ice, little is known about the behaviour of plankton there. Sea ice in the Arctic is already reducing, and the rate of loss is predicted to increase in the coming years as a consequence of climatic warming. There may be no summer sea ice in the Arctic by 2030. The loss of ice may well change the behaviour of plankton and impact significantly on C cycling in the region. Furthermore, most ice will be lost initially around the Arctic rim, over the shallow coastal seas where fisheries production is greatest: understanding consequences to zooplankton will also be vital if predictions on the effect of plankton-dependent fish species are to be made. We propose taking advantage of moorings (scientific instruments suspended in mid water on floats anchored to the seabed) already in place (supported by 'Oceans 2025' and the Norwegian Research Council) in ice-free and seasonally ice-covered fjords at Svalbard (c. 80 deg N in the Atlantic) to explore zooplankton behaviour year-round in these contrasting environments. The moorings are equipped with acoustic Doppler current profilers (ADCPs) that can track plankton migrations, sediment traps that collect plankton and their fecal matter, and temperature and salinity probes to monitor watercolumn physical properties. Any apparent differences between sites will give useful insights into how ice loss may affect the marine ecology of this sensitive region, and will help to predict future changes in presently ice-covered locations following ice retreat. This work fits with Oceans 2025 Strategic Objective 13 'Arctic Shelf Time Series'. Data will be explored in a model framework that will tell us how much fecal pellet production by zooplankton is exported to depth through the process of satiation sinking i.e. feeding at the surface and sinking into the ocean interior to digest, which can occur many times over the day and night. When this behaviour is absent most fecal pellets will remain in the surface layers and be recycled. Where zooplankton perform satiation sinking however, the amount of C particles sequestered in the ocean interior may be increased by 10-25%. The presence of ice and also of continuous light is likely to affect satiation sinking, and we will gauge what effect these factors have on carbon sequestration. We have considerable experience working on plankton migrations and on sea-ice systems. Our collaborative efforts here have the potential to provide much added value to already-funded mooring deployments, and to lead to an improved capacity to predict ecosystem consequences of change in the Arctic. The project will strengthen collaborations between UK institutions and other European/Scandinavian organisations working in Svalbard and in the wider Arctic.

Life thrives even on the sun-kissed surfaces of glaciers. But does life on ice survive in the darkened depths of Arctic winters and sediments? We know glacier surfaces are home to active microbial ecosystems. We know that in summer these photosynthesis-driven ecosystems fix carbon and darken ice as solar energy is converted to dark organic carbon. As a result, ecosystems on glaciers influence the fate of glaciers in our warming world. Until now, biogeochemists have assumed ecosystems on glaciers are only active when nourished with sunlight and nutrients in liquid meltwater in the brief melting season of summer. This constraint has framed our understanding of glacier surface ecology to the extent that the absence of evidence for active microbial processes on glaciers in winter has been considered evidence of their absence. But we now have year-round data which robustly challenges the assumption life is only active in summer. Our pilot data also reveals methane producers for the first time on ice surfaces. This project therefore tests the simple but powerful idea that glacier surface habitats are perennially active, resulting in unexpected sources of greenhouse gases. Our project proposes to address three interlinked major knowledge gaps in our understanding of glacier ecology. Firstly, we need to know what lives through the winter, secondly, we need to know what lives in thick accumulations of sediments on ice, and finally we need to know how the microbial life forms surviving through darkness influence carbon and nutrient cycles on glaciers. Our project's overall hypothesis is that glacier surfaces host light-independent microbial metabolic activities, thus allowing microbial activities in unexpected conditions with neglected contributions to nutrient cycles and greenhouse gas production. In this project we will go the High Arctic glaciers of Svalbard in every season to compare their microbial communities in the depths of polar night, the cold of the winter, the spring thaw and the height of summer. At each glacier we will collect samples for molecular analyses and measure microbial activities. We will conduct experiments to reveal how the microbes survive in these conditions, and how they interact with the carbon and nutrient cycles of the glaciers. We combine our fieldwork with carefully-controlled incubation experiments in cold labs in the UK, US and Norway. By doing this, we will have a clear picture for the first time of how life survives all seasons on Arctic glaciers and what this means for the ecology of Arctic glaciers as they face an uncertain future in the warming Arctic.

The upper atmosphere at high latitudes is a region which is bombarded by electrons and protons, which are the source of the aurora, often seen as spectacular coloured and dynamic lights in the dark sky. The aurora over Svalbard (lat 78.2 N, lon 16.0 E) where our instruments are located, has special properties which make this an ideal place to study the upper atmosphere. The location is particularly important because it is dark during the daytime in the winter months, a special property of this most northerly site. The colour of the aurora, or wavelength of the light emitted, depends on both the energy of the incoming particles and how that energy is lost during the passage of the particles, and on the composition of the atmosphere that the particles travel through. As a result, optical measurements of specific wavelengths can provide detailed information about the atmosphere, and about the energy of the precipitating populations. This project will use an advanced design spectrograph which makes measurements over a range of different wavelengths simultaneously. One emission is from excited oxygen ions O+, which is a signature of low energy electron precipitation (typically electrons with energies of about 100 eV) and has a peak brightness at around 300 km in height. We have discovered recently (Whiter et al Ap.J 2014) that the processes that produce the O+ ion in aurora have some special properties, and as a result the emission can be used to obtain the temperature of the O atoms in the region where they emit. This temperature is known as the neutral temperature, which in the auroral region has not been easy to measure so far; this project provides an exciting new method to quantify the changes that occur during auroral energy input, and to compare these changes to modelling studies and also to existing empirical models, which are known to have large uncertainties. The neutral temperature is an important parameter for studying changes on more global scales, and although our studies are from one specific location, the data we are using has been continuous during the dark hours since 2003. Another emission that we measure is from hydroxyl molecules which are excited by ultra violet radiation. The emission is known as airglow, and is from a region around 85-90 km in height, known as the mesopause. Precise measurements of these emissions can be used to obtain the temperature of the atmosphere at these heights. Consequently, we can add these observations to those described above (from around 300 km) to determine if there are any correlations, and then try to understand what the mechanisms may be. Moving a little higher up in the atmosphere, one of the strongest emissions is from molecular nitrogen, which has a peak emission height of between 100-150 km. We have developed a "synthetic spectrum" of the emission, which is a theoretical solution of the shape of the emission spectrum. This shape is dependent on the temperature of the molecules, and so we can make a best fit of the measured spectrum to the theoretical, in order to estimate the neutral temperature at the height of the emission. In combination we therefore have the possibility of measuring the neutral temperature at three distinct heights, depending on the auroral conditions. Finally we will make use of very high resolution auroral cameras which we operate in the arctic close to the spectrograph. The ASK (Auroral Structure and Kinetics) cameras provide high time and spatial resolution (1/32 s and 10 m) images of the aurora in a frame approximately 5x5 km (at 100 km altitude). ASK consists of three cameras which provide the same image at different wavelengths which, in combination with modelling, are used to find the energy input within the auroral structure. The spatial and temporal variability of precipitating charged particles is at the heart of the physics of the behaviour of the polar upper atmosphere.

Global warming is melting many of Earth's glaciers, increasing the production of meltwater as the glaciers expire. In the worst-case scenario, up to 85% of glaciers will be lost by 2100, which will then mean the production of meltwater will decline drastically. About a billion people depend on rivers fed by glacier meltwater for water, and nutrients in glacial meltwater fertilize crucial ecosystems. This glacial meltwater contains bacteria and their products. We have found some of these products are made to protect bacteria against their viruses, and have proof that these same products have a second job in dissolving nutrients from rocks. Earlier research tell us the meltwater bacteria, their products and the nutrients are critical for important ecosystems in the land and sea fed by glacier meltwater. But we do not know how many of these three things will be released as the glaciers die, how they will interact and what this change in the supply of bacteria, products and nutrients will mean for ecosystems fed by glaciers that will disintegrate this century. Our proposal aims to address these three gaps in our knowledge. In this project we will go to valley glaciers on Svalbard in the High Arctic, in Austria in the European Alps, and Livingston Island at the tip of the rapidly warming Antarctic Peninsula to see how microbes and their products are released from glaciers. At each location we will collect samples from the glacier surface which will tell us how the microbes grow in the ice surface and how they are released. We will conduct experiments to reveal how the "arms race" between microbes and their viruses affects the delivery of microbes, their products and nutrients in the meltwater. We will also sequence the DNA of microbes living in the ice surface and meltwater to see who is living in this very large, but poorly understood and endangered habitat. We will use our fieldwork and lab analyses to inform models of how glaciers release their microbes, and what this means for downstream habitats. By doing this we will have a clear picture for the first time of how the loss of glaciers will release microbes, and what those organisms may do as they are washed out to important environments downstream of the glaciers.