The Met Office provided advice for the development of a tidal flood risk management plan for the Thames estuary.
The Met Office has been doing detailed work in the Thames Estuary on flood risks, looking ahead over the next 80+ years. Work on the finalised TE2100 Plan will ensure that the right investments are made to avoid flooding or other serious water hazards that could result from climate change.
The project examined the potential future climate-driven changes in extreme water levels in the southern North Sea near the Thames Estuary up to the year 2100. The Thames Estuary 2100 Project (TE2100) is tasked with protecting London and the people living in the Thames Estuary from flooding now and into the next century.
The Environment Agency, Met Office Hadley Centre, Proudman Oceanographic Laboratory and the Centre for Ecology and Hydrology have been working together to better understand the uncertainties around future change and to relate them to plausible adaptation options.
The results suggest that future increases in extreme sea levels in the southern North Sea near the Thames estuary are likely to be driven predominately by changes in the regional time average sea level rather than local changes in storminess. However, changes in storms are projected to result in increased river flows in some parts of the Thames river catchment.
Climate scientists at the Met Office Hadley Centre combined ensemble projections, which give a likely range of future extreme water levels, with H++, a new high-end water level scenario based on observations for the basis of the report.
Our scientists have developed ten-year climate forecasts to strengthen UK contingency planning, for use alongside the 50- or 100-year time frame projections currently deployed worldwide.
Such decadal forecasts offer predictions of more direct, practical relevance to organisations where adaptation to global warming is a key operational concern. Decadal models seek to forecast natural variability, such as El Niño and fluctuations in the Gulf Stream, in addition to man-made climate change. This has already been demonstrated to improve the skill of global temperature predictions and climate forecasts on a regional basis are currently being assessed.
The Thames Barrier offers London unparalleled protection against North Sea tidal surges and holds back high tides when the river is swollen by heavy rainfall upstream. It was designed to withstand a 1 in 1,000 year severe weather event, but research by the Met Office Hadley Centre indicates that the next quarter century could see greater frequency of extreme weather events along with more torrential rain, particularly during winter months.
Key findings from the project include:
- Water levels in the Thames Estuary are likely to rise by between 20 cm and 90 cm over the next century due to thermal expansion of the oceans and additional water from melting glaciers and ice sheets caused by climate change.
- There is still much uncertainty over the contribution of polar-ice melt to increasing sea level rise. At the extreme, sea level may rise by up to 2 metres (including thermal expansion) by 2100 - although this is thought highly unlikely.
- The change in extreme water levels will be driven predominantly by the increase in mean sea-level. Changes in storminess will have less effect.
- Future peak freshwater flows for the Thames, at Kingston for instance, could increase by around 40% by 2080.
- The previous worst-case scenario of increases in maximum water levels has been revised down by approximately 1.5 metres.
- Such a reduction in worst-case scenario for this century means that a costly tide-excluding outer barrage is much less likely to be necessary to manage flood risk this century.
- Many of the Thames' defences were built following the 1953 floods and will reach the end of their design lives during the next 50 years. The system includes the Thames Barrier, over 300 km of fixed defences and numerous smaller structures.
- The Thames Barrier is expected to hold fast and continue to provide London and the Estuary communities with a higher standard of protection than anywhere else in the country. When it was built, engineers planned for 8 mm per year sea-level rise, while sea-levels are currently rising by 6 mm per year.
- However, the Thames Barrier must continue to be maintained to ensure its reliability and to reduce major costs in the future.
- Upstream plans also need adapting - to handle increased water run-off from the torrential winter rains expected as our climate continues to change.
Only the beginning...
By understanding the uncertainties around future climate change, plausible adaptation options can be recommended to protect people living in London and the Thames Estuary now and into the next century. The success of TE2100 will depend on monitoring activity in the Thames Estuary - in terms of its changing climate, people numbers and property development - and adapting to changes early as the century progresses.
The project also confirms that it's essential to monitor the rate and progress of key climate-change effects, such as polar-ice melt, and continue to invest in climate science and services to support this.
View the case-study PDF Adaptation - Thames Estuary 2100 project