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Sea-level rise

FULL REVIEW PAPER
FULL REVIEW PAPER
06_sea_level_rise_2020.pdf
Sea Level Rise
What is already happening?
  • Mean sea level around the UK has risen by about 12–16cm since 1900. 
     
  • When vertical land movement is included, the net rate of sea-level rise is slightly higher in the south of England and slightly lower in some parts of Scotland. 
     
  • At many locations, extreme sea levels that exceed critical flood-thresholds are being experienced more frequently than in the past, due to mean sea-level rise. 
     
CONFIDENCE LEVEL
HIGH

High evidence, high agreement

There is high confidence in observational evidence for mean sea levels and sea-level extremes. There is now firm evidence that the rate of sea level rise (both for the UK and globally) was higher overall in the 20th century than the 19th.

What could happen in the future?
  • For London, the central estimate projection of sea-level rise for 2100 ranges from 0.45–0.78m, depending on the greenhouse gas emissions scenario. Estimates for other capital cities are: Cardiff 0.43–0.76m; Belfast 0.26–0.58m and Edinburgh 0.23–0.54m. 
     
  • Increases in future extreme sea levels and flooding will be driven by mean sea-level changes, rather than changes in storm surges. 
     
CONFIDENCE LEVEL
MEDIUM

Medium evidence, high agreement

The UKCP18 sea level projections are a considerable improvement over previous outputs, with better representation of ice sheet processes, improved ‘downscaling’ for the UK, and a more reliable estimate of the pattern of sea-level change caused by the Earths’ elastic response to the last de-glaciation.

Key Challenges and Emerging Issues
  • Quantifying and constraining high-end scenarios through a better understanding of dynamic ice processes (and their controlling factors).
     
  • Translating updated sea-level science into resilience planning (e.g., to ensure SMPs are realistic and sustainable in economic, social, and environmental terms). 
     
  • Understanding how the storm track (position, strength) and its influence on storm surges and extreme water levels will change, with coupling CMIP6 models to storm surge and wave models a priority.