The loss of ice from ice sheets in Antarctica and Greenland is a major source of current sea-level rise, and one that is accelerating rapidly. A report from the Intergovernmental Panel on Climate Change (2007) highlighted that the greatest uncertainty in projections of future sea-level rise is due to a lack of knowledge about ice sheets. Improved understanding of key ice-sheet processes is urgently required to allow reliable predictions of future sea-level change. The BAS Ice Sheets Programme examines the role of ice sheets in the Earth System, and the processes that control ice-sheet change. It monitors current change and sets this in context with the past. BAS scientists produce tools to predict how ice sheets will change over time, allowing more accurate projections for increases in global sea level. Programme Goals are: a) to improve understanding of the ocean-atmosphere and bed interactions controlling ice-sheet flow and ice-sheet evolution; b) to build and apply a robust mathematical and numerical framework for computer simulation of ice-sheet change and sea-level rise; c) to determine current glacial change in the critical areas of the polar ice sheets; d) to establish improved histories of ice-sheet change to provide context and constraint for future projections; e) to provide robust simulations of ice-sheet change.

Earth’s environment and life are an integrated system of many parts. These interactions show complex behaviour on all scales from minutes to millennia, rocks to continents and genomes to communities. We need to understand this behaviour in order to make better predictions of future environmental changes. The BAS Environmental Change and Evolution Programme addresses key aspects in the polar regions of geological and ice-sheet structure, marine and terrestrial biodiversity, and natural complexity, that influence the unique role of the polar regions in environmental change and evolution. Programme Goals are: a) to apply and develop appropriate mathematical methods and models for analysing complex natural systems; to explain how evolutionary and past processes formed present polar biogeography and biodiversity; to determine continental structure beneath ice sheets and assess how it controls ice-sheet evolution and behaviour; to survey poorly-known areas underneath the polar ice sheets, in the deep sea, and at the edge of the atmosphere, and compile geological, geophysical and satellite-derived data to generate digital maps of key areas of British Antarctic Territory.

The BAS GEACEP Programme investigated the relationship between the evolution of Antarctic ice and the changing global environment over the last ~30 million years. It did this by collecting and combining geological data and developing computer models of the Earth as an integrated system. Its aim was to clarify the forcing and feedback mechanisms responsible for the formation of large-scale Antarctic ice cover, and to examine the stability of the permanent Antarctic ice sheet over its ~20 million year history. It used the resulting insights to check and improve the performance of computer models ('General Circulation Models') used for the prediction of climate change. Objectives were: a) to examine the nature of past warm climates over the last 30 million years; b) to clarify the forcing and feedback mechanisms associated with the climatic shift from “greenhouse” to “icehouse” conditions ~30 million years ago; c) to examine the stability of the permanent Antarctic ice sheet over its ~20 million year history.

Global ocean circulation is one of the few mechanisms by which polar processes can directly influence the whole Earth System, including the UK, and possibly on timescales as short as decades. Its importance results from the enormous capacity of the ocean to store and redistribute heat, fresh water, carbon dioxide and other climatically-important substances. The polar regions are disproportionately important in determining the strength and shape of global ocean circulation. The Polar Oceans programme investigates the role of processes and changes both in the shelf sea and in open-ocean environments, and will further our understanding of polar control of the Earth System. Programme Goals are: a) to explain the processes that drive and close the overturning circulation in the Southern Ocean; b) to determine the impact of, and the feedback between, the ocean and ice shelves; c) to understand the physical drivers of changes in the marine environment, and the likely implications for climate; d) to determine the impacts that changes in the polar regions have on the Earth System via ocean circulation; and e) to measure and understand the changes in properties in key water masses of polar origin.

The currents in the ocean are turbulent, and dominated by "eddy variability" on scales much smaller than the ocean basins. This complex, nonlinear variability makes it impossible to understand the ocean as a whole in all its detail - we can run very expensive computer models at high resolution and get realistic-looking answers, but how do we know whether their long-term predictions are also realistic? That relies on having a good understanding of the processes involved - we have to find a way to sidestep the complications of the eddies and find comprehensible aspects of the system to connect the models, via theory, to the real ocean circulation. Fortunately, when we look at the "sidewall" boundaries of the ocean, we find that the eddy effects are greatly simplified, and we get a picture of the whole ocean which can be connected to theoretical ideas. The aim of this project is to make the global ocean circulation comprehensible in terms of a small number of clearly defined processes, and hence to improve understanding of its influence on a range of important issues from sea level to heat transport. Amidst the eddying chaos, there are parts of the ocean circulation which operate on a global scale, carrying water between different ocean basins and carrying heat around the world. These modes are among the most important parts of the global climate system. One mode is the Atlantic Meridional Overturning Circulation, which transports heat to the north throughout the entire Atlantic Ocean and has a large effect on European climate. Others include the Indonesian Throughflow, which carries warm water from the Pacific to the Indian Ocean, and the Antarctic Circumpolar Current, which connects the Atlantic, Indian and Pacific oceans. The currents associated with these modes have an influence on coastal sea levels around the world, causing sea level to be higher along some coasts than others. We call the effect of these modes the "global plumbing" of the ocean. Although we have computer models which can simulate many aspects of the ocean circulation well, it is hard to model how this plumbing varies over time. Making good predictions of future climate and sea level requires us to understand the causes of variability, and to test our understanding we need good measures of how the plumbing changed in the past. The ocean's turbulence makes it very hard to measure such large scale modes. To measure the currents themselves would require an enormous number of instruments to be in the ocean at all times. But we now know that pressure on the sidewalls of the ocean encodes information about the large scale modes without the added confusion from turbulence and eddies. Processes occurring at just a few places control the pressures, and therefore the plumbing, over very large distances. In this project, we will use ocean modelling to learn how those local processes influence ocean boundary pressures, and hence the global ocean plumbing. The new understanding will then be used to determine which future changes we can have confidence in, and to direct improvements of the next generation of climate models.