Trends in UK mean sea level revisited

Abstract

SUMMARY This paper presents estimates of rates of mean sea level (MSL) change around the UK, based on a larger tide gauge data set and more accurate analysis methods than have been employed so far. The spatial variation of the trend in MSL is found to be similar to that inferred from geological information and from advanced geodetic techniques, which is a similar conclusion to that arrived at in the previous studies. The tide gauge MSL trends for 1901 onwards are estimated to be 1.4 ± 0.2 mm yr−1 larger than those inferred from geology or geodetic methods, suggesting a regional sea level rise of climate change origin several one‐tenths of mm per year lower than global estimates for the 20th century. However, UK MSL change cannot be described in terms of a simple linear increase alone but includes variations on interannual and decadal timescales. The possible sources of variation in a ‘UK sea level index’ are explored. Air pressure is clearly one such possible source but its direct local forcing through the ‘inverse barometer’ accounts for only one‐third of the observed variability. A number of larger scale atmospheric and ocean processes must also play important roles, but modelling them satisfactorily and separating the individual contributions present a major challenge. As regards future regional UK sea level changes, we conclude that there is no basis for major modification to existing projections for the 2080s included in the 2002 UK Climate Impacts Programme studies.

Response of Regional Sea Level to Atmospheric Pressure Loading in a Climate Change Scenario

“…In our analysis we find values of ib changes around the British Isles that are consistent with those of Woodworth (1987). However, we find considerably larger rates of ib changes in some regions, especially in the Southern Ocean where ib increases by about 0.6 mm yr Ϫ1 for a quadrupling of CO 2 concentrations.…”

Response of Regional Sea Level to Atmospheric Pressure Loading in a Climate Change Scenario

“…In our analysis we find values of ib changes around the British Isles that are consistent with those of Woodworth (1987). However, we find considerably larger rates of ib changes in some regions, especially in the Southern Ocean where ib increases by about 0.6 mm yr Ϫ1 for a quadrupling of CO 2 concentrations.…”

Sea Level Change in Great Britain between 1859 and the Present

“…Overall, the comparison of historical and recent data provides evidence that sea level around the UK rose during the past one and half centuries, by ∼1 mm yr −1 more than one would expect based on modelling of long-term changes in sea and land levels due to ongoing geological processes. This conclusion is consistent with the 1.4 mm yr −1 estimated for UK sea level change for 1901-onwards obtained from the permanent tide gauges in the UK network together with geological and geodetic information (Woodworth et al 2009), the period 1901-onwards being about two-thirds that of 1859-onwards. In addition, the long-term changes seem to be similar at various points around the coast.…”

Recent Change—North Sea

“…For the North Sea region as a whole, the geocentric MSL trend was 1.53 ± 0.16 mm year −1 . These results are consistent with those presented by Woodworth et al (2009a) for the UK (i.e. an AMSL trend of 1.4 ± 0.2 mm year −1 for the 20th century), but were significantly different from those presented by Shennan and Woodworth (1992) for the North Sea region (i.e.…”

Response of Regional Sea Level to Atmospheric Pressure Loading in a Climate Change Scenario

“…In our analysis we find values of ib changes around the British Isles that are consistent with those of Woodworth (1987). However, we find considerably larger rates of ib changes in some regions, especially in the Southern Ocean where ib increases by about 0.6 mm yr Ϫ1 for a quadrupling of CO 2 concentrations.…”

Sea Level Change in Great Britain between 1859 and the Present

“…Overall, the comparison of historical and recent data provides evidence that sea level around the UK rose during the past one and half centuries, by ∼1 mm yr −1 more than one would expect based on modelling of long-term changes in sea and land levels due to ongoing geological processes. This conclusion is consistent with the 1.4 mm yr −1 estimated for UK sea level change for 1901-onwards obtained from the permanent tide gauges in the UK network together with geological and geodetic information (Woodworth et al 2009), the period 1901-onwards being about two-thirds that of 1859-onwards. In addition, the long-term changes seem to be similar at various points around the coast.…”

Recent Change—North Sea

“…For the North Sea region as a whole, the geocentric MSL trend was 1.53 ± 0.16 mm year −1 . These results are consistent with those presented by Woodworth et al (2009a) for the UK (i.e. an AMSL trend of 1.4 ± 0.2 mm year −1 for the 20th century), but were significantly different from those presented by Shennan and Woodworth (1992) for the North Sea region (i.e.…”

Response of Regional Sea Level to Atmospheric Pressure Loading in a Climate Change Scenario

“…In our analysis we find values of ib changes around the British Isles that are consistent with those of Woodworth (1987). However, we find considerably larger rates of ib changes in some regions, especially in the Southern Ocean where ib increases by about 0.6 mm yr Ϫ1 for a quadrupling of CO 2 concentrations.…”

Sea Level Change in Great Britain between 1859 and the Present

“…Overall, the comparison of historical and recent data provides evidence that sea level around the UK rose during the past one and half centuries, by ∼1 mm yr −1 more than one would expect based on modelling of long-term changes in sea and land levels due to ongoing geological processes. This conclusion is consistent with the 1.4 mm yr −1 estimated for UK sea level change for 1901-onwards obtained from the permanent tide gauges in the UK network together with geological and geodetic information (Woodworth et al 2009), the period 1901-onwards being about two-thirds that of 1859-onwards. In addition, the long-term changes seem to be similar at various points around the coast.…”

Recent Change—North Sea

“…For the North Sea region as a whole, the geocentric MSL trend was 1.53 ± 0.16 mm year −1 . These results are consistent with those presented by Woodworth et al (2009a) for the UK (i.e. an AMSL trend of 1.4 ± 0.2 mm year −1 for the 20th century), but were significantly different from those presented by Shennan and Woodworth (1992) for the North Sea region (i.e.…”