1 Introduction & overview

The UK has a long maritime heritage and the marine and coastal environment continues to play an important role in the national culture and economy. United Kingdom waters cover an area approximately three times greater than its land and the UKs coastline is the longest in the EU. Over half a million people are directly employed in maritime activities (e.g. shipping, tourism, fisheries) and 95% of international trade into and out of the UK passes through its sea ports (EU Maritime Policy Facts and Figures United Kingdom). In 2004 sea-fish with an initial value of £513 million were landed by the UK fishing fleet. It has been estimated that the total turnover of the marine sector in 1999–2000 was just under £70 billion, of which almost £40 billion was due to Oil & Gas and Leisure. Beyond the direct maritime economy the UKs marine environment provides a number of important goods and services to the UK. Along the coast, more than £150 billion of assets are estimated to be at risk from flooding by the sea, with an excess of £75 billion at risk in London alone (estimated from Halcrow, 2001).

An evidence base is growing that shows that climate change is already having an impact on the marine environment across all the components that contribute to UK governments vision for “clean, safe, healthy, productive and biologically diverse oceans and seas” (Defra, 2008; MCCIP, 2008). Good estimates of what could happen in the future marine environment and how this might impact issues as diverse as flooding, habitat conservation and food safety are becoming of increasing importance for adaptation and risk planning. We provide here a set of scenarios that may be used to assess how vulnerable particular sites or sectors are to future climate change. Our interest extends outwards from the coastal zone and into the waters of the shelf seas around the UK. The chapters of this report include:

• An introduction to the climate models and ensembles (Chapter 2)
• Projections of sea level rise (Chapter 3)
• Changes in surges (Chapter 4)
• Changes in offshore waves (Chapter 5)
• A first look at a scenario of change in the surface and sub-surface temperature, salinity and circulation of the seas around the UK (Chapter 6)
• An example case study for use of the data from these models (Chapter 7)
• A more detailed description of the vertical land movement methodology (Annex).

This report can be read as a stand-alone overview of marine change around the UK, showing key findings and detailing the science used. For more detail and direct application to answer specific questions it can be used in conjunction with the UK Climate Projections User Interface. This allows access to the derived datasets from the simulations presented here (wave data are not available through the interface as the chapter has been drawn from work outside of UKCP09). The UK Climate Projections User Guidance gives advice on how the information in this report and via the User Interface can be used.

The structure and approach of the UK Climate Projections marine scenarios is very different to that of the UK climate projections over land described in UK Climate Projections science report: Climate change projections. The projections over land are based around a particular climate projection methodology that enables a probability of changes to be estimated. An alternative, simpler methodology is used in this report.

The three Science Reports, and the methodologies used to generate the UKCP09 projections, have been reviewed, firstly by the project Steering Group and Users' Panel, and secondly by a smaller international panel of experts. Reviewers’ comments have been taken into account in improving the reports.

The science is not yet at a point where the same type of approach can be reliably applied to models of the marine environment so the majority of this report presents the latest model projections as individual scenarios, providing best estimates of uncertainty ranges only where it is credible to do so. What the marine scenarios have in common with each other is that, with the exception of the changes of mean sea level, the models used to provide them are driven by atmospheric forcing from the same Met Office Hadley Centre climate model or set of models. Therefore, there is a consistency between the scenarios of changes in storm surges, shelf sea hydrography and circulation, and waves, which has previously not been possible to achieve. This means that it is now more credible to compare marine climate changes across a range of sectors. Future changes are projected for the UKCP09 Medium emissions scenario (SRES A1B, Nakicenovic and Swart, 2000) except for mean sea level rise and atmospheric variables above sea areas where all three UKCP09 projections are considered (Low corresponding to SRES B1 and High corresponding to SRES A1FI emissions scenarios). For full details of the scenarios used in UKCP09 and uncertainty in future emissions please see UK Climate Projections science report: Climate change projections, Section 2.3.

It is recognised that the mixture of presentations included in this report could be confusing to the reader, but in each case they represent what we believe to be the best scenarios given current limitations in climate modelling.

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