Industrial emissions of carbon dioxide (CO2), including fossil fuel power generation, are recognised as a likely agent of global climate change and acidification of the oceans, but most economies will remain dependent on these technologies for the next few decades. Carbon dioxide Capture and Storage (CCS) has been identified as an important way of reducing the amount of CO2 added to the atmosphere. CCS is seen as making a key contribution to reducing mankind's greenhouse gas emissions by 80-95% by 2050 and keeping climate change derived temperature increases below 2 degrees C, as outlined in European Commission policy. In addition, CCS is considered an important way of reducing the cost of mitigation measures around the continued use of fossil fuels. Offshore storage of CO2 in depleted oil and gas reservoirs and saline aquifers is the option of choice for most European nations, and there is currently one operational storage complex (Sleipner, Norway), and several other commercial scale demonstration projects are in late stages of development (e.g. ROAD-Netherlands, Peterhead and White Rose-UK), and expected to be in full operation by 2020. A key element of CCS offshore is that there is confidence that the risks of any leakage are understood. The location and potential intensity of any possible CO2 leakage at the seafloor are critically dependent on the distribution of fluid (dissolved and gaseous CO2) pathways in the rocks overlying the reservoirs in which the CO2 is stored, and on the ability of these pathways to transmit fluid (termed permeability). Recent studies of the structure of marine sedimentary rocks in the North and Norwegian Seas have revealed that near-vertical structures, which resemble chimneys or pipes, cross-cut the sedimentary sequence. These structures may be pathways for fluid flow. Natural fluids from deeper rock layers have migrated through these structures at some point in geological time. If CO2 leaking from sub-seafloor storage reservoirs reaches the base of these structures, and if their permeability is sufficiently high, they could act as CO2 leakage pathways towards the seafloor and overlying water column. To provide a reliable prediction of potential seafloor seep sites, the degree to which these pathways are continuous and especially their permeability needs to be better understood. In this project (CHIMNEY) we will collect new data over a chimney structure within the North Sea by using a ship to make novel measurements with sound waves. We will use several different marine sound sources to make images of the chimney, using receivers at the sea surface, and also record the sound arrivals on sea bed instruments known as ocean bottom seismometers. By looking at the sound travel paths through the sub-surface from a range of directions and frequencies we will obtain information about fractures/fluid pathways in the chimney as well as the surrounding rocks. We will calibrate and understand our marine seismic results using laboratory studies of materials (synthetic rocks) that mimic the sub-surface rocks. By understanding the propagation of sound through synthetic rocks with known fluid pathways we can understand the results of the marine experiment. We will also drill into the chimney and collect core samples which we will analyse for core geology and fluid chemistry. A computer model of the sub-surface chimney will be constructed combining the results of the seismic experiment, rock physics, and chemistry. We will work with companies involved in CCS to build realistic computer models of fluid flow that tell us about the potential of leakage from chimney structures generally within the North Sea that are relevant to Carbon Dioxide Capture and Storage.

THE PROBLEM: Offshore windfarms will be developed at an accelerated schedule under fast-track plans to switch away from fossil fuels. With ever larger offshore windfarms, and the cumulative effects of climate change, we thus urgently need to understand the way the seabed is modified in response and how such changes affect the wider marine ecosystem. When natural currents in the sea deviate around the wind turbines or anchors, the forces acting on the bed enhance, making sediments move and stay in suspension. This reduces the clarity of the water and changes the shape and sediment composition of the seabed, with impacts stretching far beyond the object. The seabed supports ecosystems that deliver a wide range of services incl. fishing, carbon storage, aggregates and coastal protection. The climate crisis will stretch impacts even further and into coastal zones, as future storm waves and rising sea levels will alter the ways energy from the sea is transferred to the seabed. All these changes combined can have wide-reaching impacts for organisms that live on or in the seabed, potentially changing biodiversity (species richness) and the delivery of some of these ecosystem services. The impacts at the seabed extend through the food chain to the water column and beyond as seabed dwelling fish are consumed by seabirds and cetaceans. Aggregations of fish can be strongly associated to particular seabed properties. If displacement or mortality occurs amongst these important prey species, this has knock-on effects for the deep-diving predators that cannot afford to be less efficient in foraging for food, like the seabirds that are protected by legislation. During this pivotal time of energy transition and national security, it is of crucial importance to better understand and unlock the potential of the marine environment for a renewable energy transition with added benefits to the ecosystem. AIM: This proposal sets out a strategy to assess the seabed response to the combination of accelerated windfarm expansion and accelerated climate change, and to quantify the implications for (1) biodiversity, (2) ecosystem services, (3) habitats, and (4) interactions between seabird populations and their food. We ultimately seek to help identify opportunities that benefit the conservation of species and increase biodiversity around windfarms. We will help windfarm developers design their monitoring strategies long beyond the life-span of our project. SUMMARY OF METHODS AND OUTPUTS: Via a multi-proxy study using observations, laboratory experiments and models, we will assess and map, under different climate predictions, how the stresses on the bed will be modified by 2050, how the distribution of seabed habitats and biodiversity will change, and how that drives changes to ecosystem services and the foraging success of deep-diving seabirds. We will design relevant scenarios, where we consider offshore windfarm size, scour mitigation strategies, predator behaviour and the ecosystem's vulnerability to change due to the combined effect of accelerated windfarm expansion and climate change. We will use the Eastern Irish Sea area as case study, as it is the home of a variety of seabird species with specific predator-prey relationships, of diverse seabed types and of considerable windfarm expansion nearby existing windfarms. To help all developers of windfarms in the UK, UK-scale maps will be made of the vulnerability of the seabed to change, and a new seabird vulnerability index will be developed. Our quantification of how these processes from seabed to seabirds interact can directly inform/feed into existing and future decision support tools. We will provide a tool where stakeholders can run their own simulations anywhere around the UK and for any given model/data resolution to quantify uncertainty levels of bed stress caused by windfarms, with cascading effects of uncertainty in habitat and biodiversity distribution and ecosystem services.