Improved Prediction of 21st Century West Antarctic Climate Change: the Role of the Amundsen Sea Low

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The West Antarctic Ice Sheet contains over 2.2 million cubic kilometers of ice, which if it all melted would raise global sea level by about 5 metres. Over the last few decades West Antarctica has experienced a significant warming. Air temperatures have increased across the surface of the ice sheet, but in addition warmer ocean currents have been melting the ice sheet where it reaches the ocean. The net result has been that some of the ice flowing down to the coast of West Antarctica has been accelerating and thinning so that the coastal area of West Antarctica is now contributing almost 10% to the current rise in global sea level.The climate of West Antarctica is strongly influenced by the storms over the Southern Ocean between the Antarctic Peninsula and the Ross Sea which force warm, maritime air across the ice sheet. There are a large number of storms in this area of the Southern Ocean which are collectively called the Amundsen Sea Low. This is a highly variable feature and is influenced by the ozone 'hole' and climatic conditions across the tropical Pacific Ocean.It is extremely important to know how the climate of West Antarctica will change over the coming century so that we can produce accurate estimates of sea level rise. However, the only tools we have to predict the future are computer models that simulate the atmosphere, ocean and ice across the Earth. These models run as part of initiatives such as the Intergovernmental Panel on Climate Change have a relatively coarse spatial resolution of about 200 km, which is not sufficient to accurately resolve the complex mountainous terrain of areas such as the coast of West Antarctica. For this project we will run a model with a resolution of 10 km through the 21st century to create the most detailed information yet produced of how temperature, snowfall and wind speed/direction will change as greenhouse gas concentrations increase and the ozone hole recovers. Such data will be of value to those modelling the West Antarctic Ice Sheet and enable the production of better predictions of how the ice sheet will change over the coming century and the contribution it will make to sea level rise.