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1.8 Sea level around the UK
- Sea level around the UK rose by about 1 mm/yr in the 20th century, corrected for land movement. The rate for the 1990s and 2000s has been higher than this.
Sea level around the UK, relative to land, is changing for two reasons; firstly because the volume of the oceans is changing and secondly because land is moving in response to the melting of the ice-sheet following the end of the last ice age – the latter is causing a general upward land movement in northern Britain and downward movement in southern England. The UK national network of tide gauges, the instruments by which sea level is monitored, is maintained by the Proudman Oceanographic Laboratory, Liverpool. Figure 1.16 shows observations of change in sea level from five locations around the coast of the UK which have particularly long records, with the last data point being for 2006. These changes are of absolute sea level, that is, not corrected for any land movement, as this cannot be done at individual stations with useful accuracy. However, such estimates as are available suggest that over the 20th century the effect of land movement will have been quite small at Liverpool and Aberdeen, and about 1mm/yr at Newlyn and Sheerness.
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Figure 1.16: change in annual-mean absolute sea level recorded by tide gauges at UK stations with particularly long records: Aberdeen, North Shields (Tyne and Wear), Sheerness (Kent), Newlyn (Cornwall) and Liverpool. (Source: Phil Woodworth, POL)
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The rate of relative sea-level rise (i.e. corrected for land movement) around the UK in the 1990s and 2000s is higher than that for the 20th century overall; the latter being about 1 mm/yr. Extreme high sea levels (storm surges) are also of interest; changes in these are determined by changes in sea level and storminess in combination with tides. There is evidence that annual extreme high (99%) and low (1%) sea levels at Newlyn (since 1916) and Aberdeen (since 1946), have changed at roughly the same rate as the mean sea level – 2.1 mm/yr and 1.3 mm/yr respectively – although with high extremes increasing slightly faster than low extremes. (Subsection 1.8: P. Woodworth, Pers Comm).
Further details of tide gauge measurements by POL, including extremes, can be seen on the POL website. Changes to many other marine quantities, such as salinity and waves, can be seen on the website of the Marine Climate Change Impacts Partnership. In addition, the websites of the Marine Environmental Change Network and the Marine Science Coordination Committee are useful resources.
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Last Updated Monday, 17 May 2010 |
