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The Expected Effects of Climate Change

Increasingly wet winters: the rising temperatures in the sea and air mean that more moisture is carried in the atmosphere, so the risk is of heavier rainfall during the normal wetter winter seasons – projections suggest this could be in the order of 60% more by 2050.

Increased risk of more frequent and more severe storms. In 2000 advice was to allow for up to 5cm of rain spread over two days. In 2021 Barnes had one storm with over 7cm in 4 hours, and there were two others of similar intensity locally within three weeks. This year some villages in Somerset received 9cm in two hours – with some local churches flooded, which suggests flooding was worse than historic experience, since churches have typically been built on higher ground. Exceptionally in 2021 the Ahr Valley in Germany received 25cm in 24 hours – leading to loss of life, damage to bridges and buildings ad services cut off for several days.

Heatwaves and drought: prolonged periods of hot weather and new record temperatures have become frequent: the heatwave in 2022 has, for instance, left many trees stressed into 2023.
Sea levels around the UK have risen 23cm since 1880 – with 8cm of that since 2000. Currently sea level is estimated to be rising by 1cm every three years. The Thames Estuary 2100 Plan is addressing this and tidal defences are being improved – such as the renovated non-return valves at the Beverley Brook direct channel outfalls at Tideway Yard and Barnes bridge. Plans include raising river wall defences by up to 40cm by 2065; maybe 80cm by 2100.

Tidal surges: the level of high tides in the Thames is not simply a question of sea level and variations in the moon’s gravitational pull (‘Spring tides’). Additional tidal surges can be caused by storms and by the wind’s direction, and the height reached locally depends on the energy in the tide that has to be dissipated within the narrowing embanked area. Given the expectation of both sea level rises and more frequent severe storms there is significant risk of greater tidal surges, which is why planned changes to defences exceed expected sea level rises.

The Expected Effects of Climate Change

Increasingly wet winters: the rising temperatures in the sea and air mean that more moisture is carried in the atmosphere, so the risk is of heavier rainfall during the normal wetter winter seasons – projections suggest this could be in the order of 60% more by 2050.

Increased risk of more frequent and more severe storms. In 2000 advice was to allow for up to 5cm of rain spread over two days. In 2021 Barnes had one storm with over 7cm in 4 hours, and there were two others of similar intensity locally within three weeks. This year some villages in Somerset received 9cm in two hours – with some local churches flooded, which suggests flooding was worse than historic experience, since churches have typically been built on higher ground. Exceptionally in 2021 the Ahr Valley in Germany received 25cm in 24 hours – leading to loss of life, damage to bridges and buildings ad services cut off for several days.

Heatwaves and drought: prolonged periods of hot weather and new record temperatures have become frequent: the heatwave in 2022 has, for instance, left many trees stressed into 2023.
Sea levels around the UK have risen 23cm since 1880 – with 8cm of that since 2000. Currently sea level is estimated to be rising by 1cm every three years. The Thames Estuary 2100 Plan is addressing this and tidal defences are being improved – such as the renovated non-return valves at the Beverley Brook direct channel outfalls at Tideway Yard and Barnes bridge. Plans include raising river wall defences by up to 40cm by 2065; maybe 80cm by 2100.

Tidal surges: the level of high tides in the Thames is not simply a question of sea level and variations in the moon’s gravitational pull (‘Spring tides’). Additional tidal surges can be caused by storms and by the wind’s direction, and the height reached locally depends on the energy in the tide that has to be dissipated within the narrowing embanked area. Given the expectation of both sea level rises and more frequent severe storms there is significant risk of greater tidal surges, which is why planned changes to defences exceed expected sea level rises.

Related links

Community BlueScapes

Flood Risks in Barnes

Living with Water