Year: 2009
Type: conference-paper
Abstract: Introduction: Future changes in sea levels around the UK are vital to a wide range of stakeholders, primarily because of the threat they may pose to human life, property and businesses.Understanding the science that underpins the decision-making processes in creating adaptation strategies and planning for future development is of critical importance.In two recent United Kingdom (UK) projects we have been assessing and extending the science of coastal climate change, the Environment Agency funded Thames Estuary project (TE2100) and the United Kingdom Climate Impacts Program (UKCIP).The latter also includes projections of future changes in atmospheric storminess, wave climate, shelf sea circulation and hydrography.For sea level rise (SLR) and surges, in addition to making an estimate of the likely range of 21st century changes, we have also included a low-probability high-impact SLR scenario range ("H++") to enable vulnerability testing.Methods: Global Climate Models (GCM) are the most credible tools available to study climate change, however they provide insufficient detail on regional scale for many applications.Instead, Regional Climate Models (RCM) are used to downscale the results to local scales.To quantify the intrinsic uncertainty in the climatic system, multiple realisations (ensembles) are processed on subtly different but credible models.As well as quantifying the uncertainty range this multi-model approach also provides more confidence than a single model would give.In addition to the Met Office Hadley Centre ensemble of climate models the UKCIP analysis also makes use of observed climate change data.Results: In UKCIP08, we project the likely range of absolute SLR around the UK to range from 11.6cm to 75.8cm (5th and 95th percentiles) by 2095.This includes uncertainty in current models and emissions scenarios.However, spatially varying vertical land movements lead to the relative SLR in southern parts of the UK being slightly higher than the absolute value.Taking two example locations and our mid-range SRES A1B emissions scenarios we project relative SLR during the period 1990 to 2095 for London and Edinburgh to be between 15.8cm to 63.4cm and 6.7cm to 54.4cm respectively.The absolute SLR projections of the H++ scenario, which accounts for potential acceleration of the ice sheet dynamics, ranges from around 1m to 2m.Future changes in storm surges are projected to be small around much of the UK, in many locations not exceeding natural variability.None of the return periods we studied (2, 10, 20 and 50 year) are expected to increase by more than 10cm by 2100 anywhere around the UK.However, our low probability H++ surge scenario extends this to 95cm for the Southern end of the North Sea.When the H++ surge and mean SLR components are combined it leads to a range of increases in extreme sea level by 2100 of around 1m to 3m.However, we repeat that while we think this rise is unlikely we cannot yet rule it out.For extreme wave heights we project an increase in the waters around the south-western UK, a decrease around the north of the UK, and no change in the southern North Sea, although there are large uncertainties associated with these projections.For changes in circulation and shelf hydrography we project the northwest European shelf region to show a greater warming than the expected rise in the open ocean, which is unsurprising given that the shelf is shallower than the oceanic winter mixed layer.We also found a general freshening, which was larger in the north-eastern Atlantic and North Sea than in the Celtic and Irish Seas, although this is less certain than the modelled temperature differences.Interestingly, the extent of the seasonally stratifying region is not projected to change greatly, although the strength of the stratification will increase, and these regions will stratify earlier, and remain so later into the year.Using the results for adaptation decision making: These new UKCIP08 results represent a major step forward in the type of advice we can provide to stakeholders.For the first time we are able to make estimates of the uncertainty ranges of sea level and storm surge height around the UK.We are also able to make consistent estimates of waves and shelf circulation hydrography, in all cases using appropriate state-of-the-art models.On a seasonal time-scale our wave climatology projections of future extreme wave heights in the North Sea have proved instrumental for the oil industry and the companies currently prospecting in this part of the world.Our partners are now better able to, when the need arises, cease operations and evacuate platforms in the middle of the ocean before storms carrying extreme wave heights hit their infrastructure.We hope to extend this to longer timescales using our new century scale UKCIP08 projections.That we are now able to project multiple coastal Climate Change: Global Risks, Challenges and Decisions IOP Publishing
Authors: J Lowe, Jonathan Tinker, T Howard, D de Gusmão, J Wolf, K Horsburgh, J Holt, T Reeder
Institutions: Met Office, Environment Agency
Language: English
Topic: Coastal and Marine Dynamics
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: bronze
OpenAlex ID: W1996489306