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Marine and coastal multi-level ocean projections

The Marine and coastal multi-level ocean projections provide detailed information on the potential future implications of climate change on the marine environment in UK waters.

They provide:

  • Projections of changes in water temperature, salinity, and currents
  • For 2 depth levels - near the surface and near the sea bed (NOTE: 34 depth levels, from sea bed to sea surface, are available from the  British Oceanographic Data Centre )
  • Projections of changes in the stability of the water column
  • For 12 km marine grid squares.
  • For the 30-year time period of 2070-2099 (and the baseline period of 1961-1990).
  • For the UKCP09 medium emissions scenario (IPCC SRES: A1B).

The projections have been developed using outputs from a Met-Office Hadley Centre (MOHC) regional climate model simulation to drive the Atlantic Margin application shelf sea model of the Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) (now the National Oceanography Centre Liverpool; NOCL).

The POLCOMS shelf sea model is well established having been used operationally by the UK Met Office since 2002 and used in many scientific projects by NOCL (formerly POL) and the UK research community. It has been validated with observations from marine weather stations.

Note: The multi-level ocean projections are based on a single model simulation. In contrast to some other components of UKCP09, no attempt has been made to quantify the range of future changes associated with modelling uncertainties or natural climate variability, meaning that no statements can be made about a range of uncertainty.

More information about the variables and methodology (including assumptions and caveats) are given in Chapter 6 of the UKCP09 Marine & coastal projections report, found in the Reports & guidance section.

What can I use them for?

Maps and data from the projections can be obtained from the UKCP09 User Interface . This permits the exploration of spatial and temporal variation in the variables of interest.

Multi-level ocean projections provide a range of information for a number of different variables. The mean, maximum, minimum and standard deviation are provided for the following variables:

  • Sea water potential temperature
  • Salinity
  • Kinetic energy through the water column
  • Potential energy anomaly
  • Mixed layer depth

Data is also provided on projections of stratification, for example for the day of breakdown of seasonal stratification.

What to be aware of

All of the projections in the marine report use the medium emissions (A1B) scenario only (Nakicenovic and Swart 2000). In this scenario the global mean surface temperature is expected to rise by around 1.7-4.4 ºC during the 21st century as atmospheric carbon dioxide concentrations rise to around 700 ppm. The equivalent carbon dioxide concentration (with greenhouse gas forcing from other gases also included) is estimated to rise to in excess of 850 ppm by 2100. The medium emission scenario describes a world that has rapid economic growth, quick spreading of new and efficient technologies, and a global population that reaches 9 billion mid-century and then gradually declines. It also relies on a balance between different energy sources.

Time-mean sea level rise results are also presented for the High (SRES A1FI) and Low (SRES B1) emission scenarios. The high emission scenario has similar economic and population trends as the medium emission scenario but more emphasis on power generation from fossil fuels. The low emission scenario represents a more integrated ecologically friendly world, characterised by clean and resource efficient technologies, and lower global greenhouse gas emissions. The global mean sea level for high and low emission scenarios were available directly from the IPCC Fourth Assessment. The UK deviations from the global mean sea level for the high and low scenarios were estimated from the medium emission scenario deviations using a scaling technique.

Surges, waves and shelf sea hydrography were not scaled to high and low emission scenarios because there was no clear indication what should be the choice of emission scenario scaling variable. There were also insufficient results available to us in this study to test any speculative scaling.