Arctic Climate Change and its Mid-latitude Impacts

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The Arctic climate is changing fast and its sea ice is melting at an increasing rate. Since 1979, perennial sea ice cover has shrunk by nearly half. Continuing this trend, 2011 witnessed near record losses of summer sea ice. The last five years have had the five lowest amounts of September sea ice in the modern record. This inexorable retreat of sea ice may have far reaching repercussions for the global climate system. There is an urgent need for scientific projections of future Arctic sea ice conditions to inform policy decisions. The aim of this project is to improve our understanding of Arctic climate change and its impacts on weather and climate in the northern hemisphere mid-latitudes (including the United Kingdom), and of the physical processes that govern these interactions. This objective will be achieved through complementary analyses of observations and state-of-the-art climate model experiments.Changes in the Arctic sea ice impact the atmosphere above it, and can cause large-scale shifts in weather patterns that "communicate" Arctic change to distant regions. The abnormally cold UK winters of 2009/10 and 2010/11 provide good examples of how the climates of the Arctic and the United Kingdom are connected. In these winters, unusual large-scale weather patterns led to exceptionally warm conditions in the Arctic whereas in the UK there were persistent cold temperatures, heavy snowfall and freezing rain. These resulted in disruptions to transport, energy supply and power transmission, and agricultural damage; all with significant economic costs. These record-breaking winters were preceded by reductions in summer and autumn Arctic sea ice cover. Whilst a number of studies have proposed possible connections between these, the physical processes that could explain such a connection remain unclear. Furthermore, it is unclear how future projected sea ice loss will effect the UK weather and climate. This research will use climate models to gain insight into these critical issues. In a model setting, the sea ice cover can be manipulated in a controlled manner to reveal how and by what processes it effects the wider climate system. This research aims to provide an improved understanding of the local and remote climate responses to changing sea ice conditions, and the mechanisms that govern these responses. It will shed light on whether the recent winters are relatively isolated and random events, or instead are a consequence of the dwindling Arctic ice cover. Improving our understanding and modeling of the factors affecting the climate system response to Arctic sea ice loss will improve our ability to anticipate, mitigate and adapt to future climate change, and hence the potential environmental, socio-economic and political impacts that may result.The research will be undertaken at the University of Exeter, in partnership with the UK Meteorological Office Hadley Centre and the US National Center for Atmospheric Research. It complements and extends upon a NERC-funded 5-year intensive programme of Arctic Science within the UK.