United Kingdom 2013
Cluster of winter storms in 2013-2014A sequence of powerful winter storms hit the UK between December 2013 to March 2014. Widespread flooding and coastal damage resulted in extensive power outages impacting hundreds of thousands of homes. Coastal flooding was initially fueled by heavy rains, high spring tides, and strong winds. The successive storms then brought record levels of rain onto already saturated grounds, increasing the risk of further flooding. The economic cost of these impacts over England and Wales from December 2013 to March 2014 came to approximately £1.3 billion. Not only was physical damage felt, but there were significant social impacts including depression and anxiety in communities that were flooded and cut-off.
Given the scale of the impacts, these storms triggered national action to improve adaptation measures as part of the response. A range of adaptation infrastructure has been and continues to be repaired and built in order to protect homes and businesses from the impacts of flooding.
Key impacts from the winter storms, coastal flooding and rains include:
- Residential, business and agricultural flooding
- Road closures and communities cut off due to floodwaters
- Mental health impacts in isolated communities cut off during the flooding
- Reduction in tourism, leading to reduced economic activity
- £1.3 billion in damages
Geographical context
The winter storms affected communities across England, Wales, Scotland and Northern Ireland. Wind speeds above 70 knots (kn) were recorded along exposed coastlines, with gusts exceeding 100 kn on some of Scotland’s mountain summits. The total rainfall between December and January was over 370 mm for southeast/central England, which was the wettest two-month period on record since 1910.
Due to the extensive impacts in the Somerset region of England from flood-related damage, this was chosen as the focus area for the study. The Somerset Levels are a flat, low-lying area of Somerset, with 18% of the Levels lying below the average tide level. The Bristol Channel has one of the largest tidal ranges in the world of ~15m, and Somerset also has two major rivers, the Parrett and the Tone, which are tidal for a large distance inland. Therefore, Somerset is very vulnerable to multivariate flooding from coastal, fluvial and pluvial influence.
Figure 1 Observed flood extent over the entire Somerset Region from December 2013 to March 2014.
Figure 2 Simulated flood extent and depths under observed atmospheric forcing conditions for the selected region of the Somerset Levels.COMPOUND HAZARd
The UK winter storms of 2013–2014
The UK winter storms of 2013-2014 were a series of low-pressure systems that formed over the North Atlantic, fuelled by a powerful Atlantic jet stream. The positive state of the NAO, alongside other teleconnections, contributed to the development of a conveyor belt of storms throughout the winter.
The systems began to move towards the British Isles with the first storm arriving in early December 2013, bringing a storm surge - which is when the water level rises in response to low air pressure above it - that coincided with high tides in the North Sea, compounding the hazard. The combination of particularly long-period ocean swells, strong winds and high spring tides led to dangerous and damaging coastal conditions in southwest England and South Wales throughout the winter. This included exceptionally large waves; for example, in February 2014 a record-breaking 25m wave height was recorded off the south coast of Ireland.
Through late December and into January 2014, the weather pattern remained in place, continuing to push storms into the UK. As the systems continued to arrive in rapid succession, the southwest of England experienced back-to-back windstorms. Each storm brought further hazards which compounded risks; in the Somerset Levels, persistent and heavy precipitation filled drainage ditches, fields, and villages, creating flooding that persisted for weeks. The winter rainfall total in the Somerset region was 536.6mm, a record which is still held to this day.
By late February and early March 2014, the storm sequence finally eased as the system shifted northwards. Flood levels slowly decreased, and evacuated residents returned home. What remained was the need to address and respond to the widespread impacts on households, transportation, farmland, and coastal flood prevention infrastructure.
Observed impacts
The UK’s 2013–2014 winter storms caused extensive losses
to people and the economy
The impacts of the UK’s 2013–2014 winter storms spread across the country from coastal zones to inland regions. Heavy and persistent rainfall was a primary driver of compounding impacts; repeat precipitation on already saturated soils triggered inland flooding, compounded by overwhelmed drainage systems. The Somerset Levels for instance experienced some of the most severe flooding in decades. Rivers overflowed into farmland and villages and several communities were cut off for extended periods, which required evacuations by boat, and left many residents temporarily displaced for months.
Elsewhere, sustained high river levels, such as in the Thames Valley, resulted in flooding with homes and transport routes repeatedly inundated. Across the country, travel was severely disrupted with roads submerged, train lines blocked by fallen trees or flooding, and ferry services cancelled during major storms. In Cornwall and Devon, massive waves severely damaged sea walls and coastal infrastructure including transportation infrastructure, with one incident where powerful waves destroyed a section of the main railway line, which cut off rail access to the southwest region of England for a number of weeks.
The powerful storm surge in early December caused widespread coastal flooding along the east coast of England, with ageing coastal protection infrastructure quickly overtaken along the coast. Hundreds of homes were flooded, rivers flooded onto surrounding land, and several communities were temporarily evacuated due to inundated roads and waterfront properties. At the beginning of February, a particularly severe storm caused further destruction to coastal infrastructure and brought extreme winds which led to long term power outages.
The storms occurred against a backdrop of ageing and underfunded infrastructure, alongside growing populations and development, including in flood plain areas. This growth, particularly in vulnerable areas such as the Somerset Levels, increased exposure to flooding and storm surges. Flood protection measures, particularly related to drainage systems and storm surge protection along coastlines, were in need of repair and funding. Although the population across the Somerset Levels is more dispersed, there was significant damage to the agricultural sector in the region due to the heavy concentration of agricultural activity.
Alongside this, the UK was still recovering from the 2008 financial crisis, which negatively affected national investments in flood-defence measures. In addition, rural transport and interconnectivity was minimal, which exacerbated the impacts of flooding-related isolation of communities, contributing to the social and mental health consequences in the aftermath.
This series of storms demonstrated how cascading and compounding hazards can interact across time to amplify the impacts of these events particularly where there is little time to recover between them.
Displacement
Many residents faced long-term displacement as repairs to damaged homes progressed slowly.
Infrastructure damage
Critical infrastructure, including railway lines and coastal flood prevention infrastructure, required extensive reconstruction.
Economic impacts
Agricultural land remained flooded for months, delaying planting and reducing yields. Economically, the combined impacts of the storms, including property damage, transportation disruptions, and business losses, resulted in approximately £1.3 billion.
Impact summary
Summarises the impacts for the Somerset region
Residential properties flooded internally
Road closures
The Muchelney community was cut off by flood waters for over 2 months
The major railway line between Bridgewater and Taunton was closed for weeks
Flooded pasture
Flooded arable land
of businesses were either directly or indirectly impacted by flooding
of businesses were impacted by road closures
farmsteads significantly flooded
'Devastating' impact on mental health,
depression and anxiety in flooded
and cut-off communities
Lost tourism days due to the flooding in Somerset
Response
Emergency services worked continuously to reinforce flood defenses and support affected households, with a total of 957 emergency service personnel deployed. Floodwater pumping was conducted to drain fields and villages inundated with flood water, with 128 pumps operating at the peak of the effort. The total cost of services was estimated to be £16.8m ± 2.5m. In response to the 2013-14 winter floods, the Somerset Rivers Authority (SRA) was formed to work with partners and stakeholders to reduce the risks from flood impacts in the Somerset county.
A 20-year action plan was put forward, introducing more than £20 million in funding to repair damaged local infrastructure and manage future flood risk for the area, which is supported by Somerset County Council. Since 2014, work has been carried out adding and improving culverts, drains, flood relief channels, raised roads, control structures and flood banks, as well as carrying out dredging of the Parrett and Tone rivers. The Bridgwater Tidal Barrier – a £249 million project - is currently under construction and due to be completed in 2027, which aims to protect over 11,300 homes and 1,500 businesses from flooding.
Attribution analysis
We use rainfall data from large-ensemble climate model runs, which are run in both the current climate (factual) and a climate without anthropogenic influence (counterfactual) to examine how climate change influenced the event. These runs, from the HadGEM3-A model (Ciavarella et al., 2018), are simulated using observed Sea Surface Temperatures (SST) and Sea Ice Conditions (SIC) for the factual climate. The counterfactual (preindustrial) climate simulations have the SST and SIC signal from climate change removed from the observed values before they are run. Over 300 factual and 300 counterfactual rainfall profiles for winters are run through a flood modelling framework (Jack et al., 2025), to assess how any changes in the hazard due to climate change translate into impacts.
In addition to the climate counterfactual, we also use an exposure counterfactual, to examine how population and economic changes may have affected the impacts of the event. The HANZE v2.0 exposure dataset (Paprotny, 2023) was combined with the flood extent map of the observed event; to show how many people would have been exposed to this flooding event, given the population in 1870 till 1980 (counterfactual) and the population in 2013/14 (factual).
Attribution results
Climate change is found to have marginally increased the magnitude of the flood extent over the Somerset Levels in England during the winter of 2013/14, with events of such magnitude 1.21 times more likely than in a world without anthropogenic climate change. The confidence intervals on the results contain large uncertainties however, from 4.5 times more likely to 3.0 times less likely, and therefore there is low confidence in the results. The return period for the flood extent was found to be a 1-in-206-year event in the current climate and 1-in-249-year event in a preindustrial climate. The equivalent event in a pre-industrial climate would have a flood extent of 113 km2 (95% CI: 110-116) instead of 114 km2 (95% CI: 111-117).
Figure 3 Comparison of flood extent from factual climate (gold) and counterfactual climate (green) runs in terms of a) probability and b) return period
There were several factors that we kept constant in the methodology for both a factual and counterfactual climate, including the tides, river flows at the start of the simulations, and sea-level. Using a climate counterfactual for these factors as well may have led to different results, especially sea level rise.
Figure 4 The population that would be exposed to the flooding for 2013/14 over the Somerset Levels, if occurring in a different year.
Changes in the population exposed to flooding due to the climate signal were found to be small; however, there was a high increase in the population exposed to flooding, due to population growth since the 1880s in the region examined. Furthermore, the worst impacts of the event predominantly affected the agriculture sector, transport networks and businesses, and therefore counterfactual exposure datasets that include these aspects would provide the most useful information on how exposure to such events have changed over time.
Policy implications
Over the last 10 years, more than £45 million has been put forward to support the efforts of the SRA. A further 10-year 2024-34 strategy is currently under implementation to further reduce flood risk and impacts in the county under a changing climate.
Climate adaptation plans for towns in Somerset have recently been funded by the SRA, which are still in their developmental stages, with solutions across environmental domains being implemented both at a community and local government level. For example, Glastonbury Town Council has worked with the Somerset Wildlife Trust to produce a plan which identifies key priorities in building resilience to the impacts of climate change; including planting more trees in urban and suburban environments, adapting to flooding in residential, industrial, and public spaces, and installing green roofs on schools, public buildings, and infrastructure.