Rising sea levels in the English Channel 1900 to 2100

Abstract

There is great concern about rising sea levels in the coming century, particularly in terms of extreme sea levels and the increased likelihood of coastal flooding. This is especially true for the south-east coast of England where rising sea levels interact with a growing population and economy. This paper examines how extreme sea levels (excluding waves) have changed through the twentieth century at 16 sites around the English Channel. Extreme sea levels were found to have increased at all 16 sites, but at rates not statistically different from the observed rise in mean sea level. Potential future changes in extreme high sea levels throughout the twenty-first century are estimated for nine UK south coast sites using the 2009 projections from the UK Climate Impacts Programme. For the low, medium and high emissions scenarios (12, 40 and 81 cm total ocean rise, respectively), the exceedence frequency of extreme high sea levels along the south coast would on average increase over the twenty-first century by a factor of 10, 100 and about 1800, respectively. Finally these changes are considered in relation to a large recent surge event in March 2008, which caused significant flooding in the central Channel. There is great concern about rising sea levels in the coming century, particularly in terms of extreme sea levels and the increased likelihood of coastal flooding. This is especially true for the south-east coast of England where rising sea levels interact with a growing population and economy. This paper examines how extreme sea levels (excluding waves) have changed through the twentieth century at 16 sites around the English Channel. Extreme sea levels were found to have increased at all 16 sites, but at rates not statistically different from the observed rise in mean sea level. Potential future changes in extreme high sea levels throughout the twenty-first century are estimated for nine UK south coast sites using the 2009 projections from the UK Climate Impacts Programme. For the low, medium and high emissions scenarios (12, 40 and 81 cm total ocean rise, respectively), the exceedence frequency of extreme high sea levels along the south coast would on average increase over the twenty-first century by a factor of 10, 100 and about 1800, respectively. Finally these changes are considered in relation to a large recent surge event in March 2008, which caused significant flooding in the central Channel.