Monitoring and responding to sea level rise  

In our recent blog post, we introduced our August climate theme of sea level rise, explored some of the different aspects, and looked at how climate change can influence sea levels at a global and regional scale. In this blog, we will be taking a closer look at this topic to find out how sea levels are monitored and the actions that can be taken in response to changing sea levels.  

Monitoring sea level rise  
Climate scientists monitor sea levels to understand how they have changed over time, and to inform projections of how they might change in the future and the impacts that these changes might cause. Sea level is monitored by tide gauges and from space by satellites.   
  
The Global Climate Indicators are a set of parameters that describe the changing climate, looking beyond temperature as the only indication of climate change. They comprise key information for the most relevant domains of climate change: temperature and energy, atmospheric composition, ocean and water as well as the cryosphere. These indicators provide additional information and allow a more detailed picture of changes to our climate.  

The Met Office climate dashboard provides a comprehensive way to stay up to date on the current state of the climate by providing data based on observations of these key global climate indicators, one of which is sea level rise.   
  
Nick Rayner, who leads the Met Office’s Climate Monitoring team said of the dashboard:  
“Observations from coastal tide gauges show sea levels rose by nearly 200mm between 1900 and 2000. However, by building in projections of sea level rise linked to different scenarios for future greenhouse gas emissions, you can easily see what we are already committed to and the need for urgent action to minimise further changes.”   

You can view the sea level dashboard here.  

How much could sea levels rise?  
In August 2019, the Met Office Hadley Centre produced a set of UK- focused sea level projections for a report which was published by the Environment Agency. The projections demonstrated that under all emissions scenarios, sea levels would continue to rise well beyond the year 2100, although the rate and severity of the rise would depend on the level of emissions.   

Figure 1. Time series of the time-mean relative sea level change for UK capital cities based on the nearest Class A tide gauge location (indicated in brackets). Notes: Solid lines indicate the central estimate and dashed lines indicate the 5th to 95th percentile range for each RCP scenario as indicated in the legend (top left panel). All projections are presented relative to a baseline period of 1981 to 2000.Source: UKCP18 Marine Report (Palmer et al. 2018b, Figure 3.1.4)  

Matt Palmer, who leads the sea level projection work at the Met Office said: “As part of the UKCP18 national climate projections, we developed a new set of sea level projections with information available all the way to 2300. These longer time horizons are needed to fully appreciate the future sea level rise we will need to adapt to under different amounts of future climate change. Even under immediate and sustained reductions of greenhouse gas emissions, the UK will need to be prepared for 1-2 m of future sea level rise.”   
  
Sea level rise impacts   
Rising sea levels can cause a myriad of impacts, from changing the shape of our coastline and beaches, to threatening infrastructure and the homes of people who live in coastal communities. Rising sea levels can also threaten the survival of already fragile wildlife habitats.  

As the sea level rises around the UK it exposes more areas of coastal land to larger and more frequent storm surges and wind-driven wave impacts. In February 2014, a storm destroyed a section of the seawall in Dawlish, Devon, leaving the railway line suspended in mid-air. This line was the only one linking Cornwall to the rest of the country, so its damage caused significant travel disruptions. Reconstruction of the sea wall and train line cost millions of pounds, and it wasn’t until April 2014 that the line was reopened.  

Major infrastructure close to the sea such as the main Devon to Cornwall rail link at Dawlish will be increasingly vulnerable to rising sea levels and storm surges.

Tackling sea level rise – a combined approach  
Research tells us that climate change influences sea level rise, and we know that even if we were to curb emissions of greenhouse gases, we are already committed to substantial sea level rise over the coming century and beyond, based on the concentration of greenhouse gases that are already in the atmosphere. With this in mind, how can we respond to the threat of rising sea levels, and is there anything that can be done to limit this progress? The answer lies in a combined approach.

Mitigation will be a vital strategy in stabilising the rate of climate change-induced sea level rise. Climate change mitigation involves finding ways to limit the progress of climate change and its resulting impacts. Methods of mitigation include investment in renewable energy sources, carbon-neutral schemes and a reduction in carbon emissions.

Dr Helene Hewitt OBE, Met Office sea level rise expert, said, “Without strong action to tackle climate change we could see global sea levels rise by a metre by 2100, depending on the greenhouse gas emission scenario: that could be up to five times the rate or more in the next 100 years, compared with the previous century. Even with aggressive action to cut greenhouse gas emissions, global sea levels will continue to rise.”  
  
Climate change adaptation involves finding ways to adapt to the impacts of climate change that are already happening. Given that we are already committed to substantial future sea level rise, it is important that decision makers consider adaptation alongside mitigation in order to minimise the impacts that we experience.

Adaptation strategies should be informed by regional climate modelling and risk analysis, and flood modelling of how climate change will affect future flood risk so appropriate adaptation measures can be designed for at-risk areas. Environment Agency guidance, including Flood risk assessments: climate change allowances and Flood and coastal risk projects, schemes and strategies: climate change allowances, can be used to help with flood modelling and assessment.  

Another possible nature-based adaptation strategy is managed realignment. This involves using natural coastal landforms to act as a defence against coastal erosion and flooding, as opposed to the use of artificial structures like sea walls. An example of managed realignment is the creation of “inter-tidal zones” – areas of low-lying land on the coast that are allowed to flood with the advancing tide, forming mudflats which serve to protect inland areas.  

How can the UK adapt to sea level rise?  
In January 2022, the UK Government published the UK’s Third Climate Change Risk Assessment (CCRA3) which sets out the risks and opportunities facing the UK from climate change. This was informed by the Climate Change Committee’s independent advice report, which identified sixty-one UK-wide climate risks and opportunities cutting across multiple sectors of the economy.   

Of these sixty-one risks or opportunities, the risk assessment concludes that thirty-four are ranked as ‘more action needed’ including risks to people, communities and buildings from coastal flooding and sea level rise.   

Earlier this year, the Environment Agency published their Flood and Coastal Erosion Risk Management Strategy Roadmap to 2026 which provides a plan to deliver its strategy’s vision for a nation ready for, and resilient to, flooding and coastal change – today, tomorrow and to the year 2100. The roadmap sets out the practical actions to achieve the ambitions in the strategy and tackle the growing threat of flooding from rivers, the sea and surface water as well as coastal erosion. It also delivers a host of wider benefits, including local nature recovery, carbon reduction, more integrated water management, and improved forecasting of flood events. These actions will increase our resilience to flooding events for homes, businesses and infrastructure across the country.  

During August, we will be exploring the topic of sea level rise and its wider impacts, both here in the UK and from a global perspective. Follow #GetClimateReady on Twitter as we explore this theme.  

Get ready for tomorrow #GetClimateReady  
 

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