Northern sea ice levels are at an historical and millennial low, and nowhere are the effects of contemporary climate change more pronounced and destructive than in the Arctic. The Western Arctic rim of North America is considered the climate change "miners canary", with temperatures increasing at twice the global average. In the Yukon-Kuskokwim Delta (Y-K Delta), Western Alaska, the indigenous Yup'ik Eskimos are facing life-altering decisions in an uncertain future, as rising temperatures, melting permafrost and coastal erosion threaten traditional subsistence lifeways, livelihoods and settlements - the Yup'ik face becoming "the world's first climate change refugees" (The Guardian 2008). For the Yup'ik, however - whose relationship to the total environment is central to their worldview - coping with global climate change entails far more than adapting to new physical and ecological conditions. This is reflected in the holistic incorporation of both natural and social phenomena embodied in the use of the Yup'ik word ella, (variably translating as "weather", "world", "universe", "awareness"), which is understood in intensely social as well as physical terms. Ella reflects the relationship Yup'ik society has with the natural world. As changing environmental conditions jeopardise traditional subsistence practices in the Arctic, their deep-rooted dependency and social connection to the land is also threatened - further severing their ecological ties and compromising their cultural adaptive capacity that has defined Yup'ik community and identity for thousands of years. Rapid climatic change is by no means a uniquely modern phenomenon and the indigenous cultures of this region have faced such life-changing situations before. In fact, Western Alaska has experienced pronounced climatic variations within the last millennia, with the forebears of the Yup'ik being similarly challenged by regime shifts that would have influenced the availability of important subsistence resources, much the same as their descendants face today. The ELLA project will use both the products and processes of archaeological research to understand how Yup'ik Eskimos adapted to rapid climate change in the late prehistoric past (AD 1350-1700), and to inform and empower descendant Yup'ik communities struggling with contemporary global warming today. Taking full advantage of the spectacular but critically endangered archaeological resource now emerging from melting permafrost along the Bering Sea coast, this community-based project will illuminate the adaptive capacity of the precontact Yup'ik; build sustainable frameworks for the documenting of local sites under threat; and reinforce Yup'ik cultural resilience by providing new contexts for encountering and documenting their past.

The Arctic is changing rapidly, and it is predicted that areas which are today tundra will become tree-covered as warming progresses, with, for example, forest spreading northwards to the coast of northern European Russia by 2100. In some parts of the Arctic, such as Alaska, this process, commonly referred to as "greening", has already been observed over the past few decades; woody shrubs are expanding their distribution northwards into tundra. Such vegetation changes influence nutrient cycling in soils, including carbon cycling, but the extent to which they will change the storage or release of carbon at a landscape scale is debated. Nor do we fully understand the role that lakes play in this system although it is known that many lakes in the tundra and northern forests are today releasing carbon dioxide and methane into the atmosphere in significant amounts, and a proportion of this carbon comes into the lake from the vegetation and soils of the surrounding landscape. Lakes form an important part of arctic landscapes: there are many thousands of them in our study areas in Russia and west Greenland, and they act as focal points for carbon cycling within in the wider landscape. It is vital that we understand the interactions between plants, soils, nutrients, and lakes because there are massive carbon stores in the high northern latitudes, particularly in frozen soils, and if this carbon is transferred into the atmosphere (as carbon dioxide (CO2) or methane) it will create a positive feedback, driving further global warming. For this reason, the Arctic represents a critical component of the Earth System, and understanding how it will it respond to global environmental change is crucial. Lakes are a key link in this process. As lakes are tightly coupled with terrestrial carbon cycling, changes in the flows of carbon to a lake are faithfully recorded in lake sediment records, as are changes in the biological processing of that carbon within the lake. We also know that similar vegetation changes to those observed or predicted today occurred in the past when climate was warmer than today, and thus past events can provide an analogue for future changes. This project will examine lake sediment records, using techniques that extract a range of chemical signals and microscopic plant and animal remains, to see how vegetation changes associated with past natural climate warming, such as migration of the tree-line northwards, affected lake functioning in terms of the overall biological productivity, the species composition, and the types of carbon processing that were dominant. Depending upon the balance between different biological processes, which in turn are linked to surrounding vegetation and soils, lakes may have contributed mostly to carbon storage or mostly to carbon emissions ?at a landscape scale. Changes in vegetation type also influence decomposition of plant remains and soil development, and this is linked to nitrogen cycling and availability. Nitrogen is an important control over productivity and hence of carbon fixation and storage, and thus it is important to study the dynamics of nitrogen along with those of carbon. Due to the spatial variability of climate and geology, the pace of vegetation development (and of species immigration) and the types of plants involved have not been uniform around the Arctic. By examining several lakes in each of three regions (Alaska, Greenland, Russia) we will be able to describe a broad range of different vegetation transitions and the associated responses of the lakes. Our results can be used to inform our understanding of the likely pathways of recently initiated and future changes. They can also be up-scaled to the whole Arctic and so contribute to the broader scientific goal of understanding feedbacks to global warming.

The subject of our study is the aurora borealis, or northern lights, which is an amazing natural lightshow in the sky, seen regularly at high latitudes such as northern Scandinavia, but rarely at the latitudes of the UK. We use the aurora as a diagnostic to find out many things about the environment around the Earth, mainly in the region of upper atmosphere called the ionosphere. That environment is made up of 'plasma' (ionised gas) often called the fourth state of matter, which makes up over 95% of the directly observable material in the cosmos. Yet it is strangely difficult to maintain and study within Earth's biosphere. The upper atmosphere provides an ideal natural laboratory for its study since there is no need to consider collisions of the plasma with container walls. The story of the aurora begins at the Sun, which is a continuous but very variable energy source, in the form of a plasma stream (the 'solar wind') which impacts on the Earth. We are interested in understanding the smallest scale auroral structures, and how the energy changes within them influence the large scale environment. To study the aurora, we use a special instrument which has three cameras looking at different 'colours' simultaneously. The proposed research is for studies of very dynamic and structured aurora at the highest possible resolution. The instrument is named ASK for Auroral Structure and Kinetics. It was designed to measure a small circle of 3 degrees in the 'magnetic zenith' i.e. straight up along the Earth's magnetic field. Particles from the Sun spiral along these imaginary magnetic field lines, and lose energy when they collide with atmospheric oxygen and nitrogen. The exact colour (or wavelength of the light) depends on how much energy the incoming particle started with, and what molecule or atom it hits. The ASK cameras help to unravel this complicated process by making very precise measurements in space and time of three emissions which have different physical origins. We will combine these optical measurements with measurements from special radar experiments, which are designed to use a technique known as interferometry to measure structures smaller than the beam width, and with accuracy of position and height better than has been possible to date. The radar imaging technology is new in the field of incoherent scattering radar and will be one of the cornerstones of a future project that is called EISCAT_3D. The technology employed is Aperture Synthesis Imaging Radar (ASIR). It is very similar to the technology used by radio astronomers (VLBI, Very Long Baseline Interferometry) to image stellar objects, and also has some similarity with the SAR (Synthetic Aperture Radar) technique used onboard airplanes and satellites to map the Earth's surface and other planetary surfaces. In the radio astronomy case the source itself spontaneously emits radiation that is collected by a number of passive antennas. In ASIR, the radar transmitter acts like a camera flash to illuminate the target (the ionosphere or atmosphere) and a number of antennas collect the scattered radiation exactly as in the radio astronomy case (or like the lens of a camera). From this point on, the two cases are essentially identical. To construct the image of the target, the cross-correlation between the signals is calculated from all different pairs of receivers. By using the radar imaging technique we will become the pioneers of this new technique in Europe.

Sea ice extent in the Arctic Ocean has seen a steady decline since satellite-borne measurements began in the late 1970s. Sea ice supports the growth of ice algae, a fundamental component of the Arctic carbon cycle, providing food to Arctic animals. When sea ice melts every spring, ice algae are released to the water where they are either consumed by pelagic animals, or sink to the seafloor. Gaining an accurate understanding of these pathways for this important energy rich carbon resource represents a major scientific challenge that holds the key to understanding the future of Arctic ecosystems. However, until recently, this has not been possible because of the challenges associated with distinguishing sea ice carbon from other similar sources of carbon, such as phytoplankton. Having recently overcome these challenges in the last 3 years, it is now possible to unambiguously trace the pathway of sea ice-derived carbon. Recent findings have therefore shown that sea ice-derived carbon can be found in Arctic animals year-round. This is believed to be because excess (not consumed during sinking) sea ice-derived carbon that sinks can also become 'stored' within sediments where it can remain available as a food source to animals year-round. Consequently, if this idea is correct, our present assumption of the role sea ice carbon plays in the ecosystem is severely underestimating its importance. This project will bring together the expertise of British, Canadian and American scientists in a new collaborative partnership to assess whether the seafloor (e.g. rock, sand, mud, silt) acts as a 'store' of Arctic sea ice-derived primary production that can be considered available for marine animals to consume. Completion of the project aims relies upon collaboration between Brown's established (Mundy) and new (Iken) links within the assembled team. We will carry out studies on the marine region around Southampton Island, northwest Hudson Bay (Nunavut) which encompasses one of Canada's largest summer and winter aggregations of Arctic marine mammals. By sharing resources with a funded Canadian research project we will access a unique field site to collect primary preliminary data to improve understanding of ecosystem structure and function. Our findings will be relevant to the whole Arctic region and so will stimulate new research interests on an international scale.

Velocity profiles of the Earth's upper mantle are characterized by discontinuous jumps of the seismic velocities. The main velocity discontinuities (or simply discontinuities) are located at depths of approximately 410 and 660 km. Both of these discontinuities can be explained by solid-solid phase transitions in the major olivine component of the mantle material. Nonetheless, the minor constituents of the mantle material will introduce additional, mostly smaller, discontinuous jumps of the velocities at different depths. These transitions complicate the seismic image of the upper mantle structure. High resolution studies are necessary to detect these discontinuities and to image the fine scale structure of the upper mantle with strong implications for the mineral-physical constitution of the Earth's mantle and geodynamical modelling of dynamics and evolution of Earth's mantle. We propose to use traveltime and waveform information from data recorded at seismic arrays located in India and Australia to resolve the structure of the upper mantle beneath northern Australia and northern and eastern India. Major earthquake belts are located in a distant range from these arrays that allows the study of the seismic wave triplications due to the velocity increases at the discontinuities. Several thousand earthquakes recorded at the arrays will be collected to achieve a dense coverage of the study area. Using time series stacking techniques we are able to resolve the different branches of the triplication and measure traveltimes with high precision. Using this information in forward modelling schemes will allow us to develop models of the upper mantle velocity structure and the depth location of the discontinuities. Furthermore, stacking techniques lead to increased signal-to-noise ration of coherent arrivals allowing us to use waveform information from subtle arrivals originating from the upper mantle discontinuities. We will use waveform modelling of the triplicated arrivals and of S-to-P conversions at the discontinuities to resolve the fine scale structure of the velocity increases. One-dimensional and high-performance wave propagation techniques will be used to model the effect of the fine-scale structure of the discontinuities onto the wavefield. This study will put important constraints on the composition and dynamics of the upper mantle in different tectonic regions of the Earth including a continent-continent collision zone and recent oceanic subduction.