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Coastal storm surge projections

The UKCP09 storm surge height projections provide possible future changes in surge height and also combined changes in surge height and time-mean sea level rise.

The projections use the National Oceanography Centre storm surge model (POLCS3). This model is currently used to provide coastal forecasts of surge in the UK, as part of the UK Coastal Monitoring and Forecasting service, to support the issue of coastal flood warnings by the Environment Agency and other similar bodies.  

Use of POLCS3 has shown that the model is relatively reliable when driven by realistic weather information, and in the Thames Estuary 2100 Case studies it was shown to be capable of replicating observed extreme storm surges in the southern North Sea and Thames Estuary.

The UKCP09 marine & coastal storm surge information provides projections of surge height:

  • of the linear trend and 5th and 95th percentiles throughout the 21st Century for 2, 10, 20 and 50 year return period events (including statistical significance);
  • for each 12 km coastal grid square;
  • for the UKCP09 medium (IPCC SRES: A1B) emissions scenario in addition to;
  • that reflect some aspects of the uncertainty in modelling global and regional climate change - this was done by using eleven different variants of the Met Office Hadley Centre climate model HadCM3 to drive eleven corresponding variants of the HadRM3 regional model, which in turn drove POLSC3;
  • that sets the projections in context by using results from different global climate models to demonstrate that the projections do not cover all plausible future outcomes;
  • that include a high risk, low probability scenario to reflect the considerable uncertainties about the upper limit of coastal storm surge projections and inform thinking about the limits to adaptation.

Note: Unlike some other components of UKCP09, the storm surge height projections are not probabilistic, although a range is provided based on the assumption that the 11 simulations are equally likely.

More information about the storm surge methodology (including assumptions and caveats) are given in Chapter 4 of the UKCP09 Marine & coastal projections report, found in the Reports & guidance section.

What can I use them for?

Plots and data from the projections can be obtained from the UKCP09 User Interface . They can be used to assess temporal and spatial vulnerability along the UK's coastline.