Strategy: adapting to and mitigating climate change

Our strategy to adapt to a changing climate and how we manage uncertainty

Adapting to the impacts of climate change needs to accommodate the levels of uncertainty in the global delivery of a 1.5°C rise. There is a large degree of uncertainty in the longer term because of outcomes from different emissions scenarios and the complexity of climate modelling.

Climate change trends are occurring slowly against the backdrop of normal, natural weather variation which makes it challenging to identify when climate change is happening and when trigger levels are reached. Our strategies are increasingly cognisant of that uncertainty and seek to deliver flexible and adaptive plans that can evolve as the reality emerges.

Across our strategy and planning framework we assess the impact of climatic change in rainfall, temperature and storms (wind speed). In addition to the 1.5°C rise targeted globally, we assess various scenarios at both 2°C and 4°C. This is critical to managing uncertainty and establishing a baseline from which we can understand future performance and where we are at risk of failing to meet strategic planning objectives such as internal flooding, wastewater treatment works compliance and the supply demand balance.

Understanding the range of weather impacts is therefore central to our scenario baseline and the potential future variations used are set out below.

Projected changes for North West England at a global mean warming of 2°C above pre-industrial levels. Aligned to the UK Climate Projections 2018 (UKCP18) Derived Projections of Future Climate over the UK, Met office (November 2018).

Type of changeLowMedianHigh
Winter temperature0 to +1°C+1 to +2°C+2 to +3°C
Summer temperature0 to +1°C+1 to +2°C+2 to +3°C
Winter rainfall-10%+10%+20%
Summer rainfall-30%+10%+20%
Winter wind speed-0.6m/s-0.2m/s+0.4m/s
Summer wind speed-0.4m/s-0.2m/s+0.2m/s
Daily temperature (min/max) – winter+1.5°C+1.0°C
Daily temperature (min/max) – winter+2.0°C+2.0°C

Projected changes for North West England at a global mean warming of 4°C above pre-industrial levels. Aligned to the UKCP18 Derived Projections of Future Climate over the UK, Met office (November 2018)

Type of changeLowMedianHigh
Winter temperature+1 to +2°C+2 to +3°C+3 to +4°C
Summer temperature+2 to +3°C+3 to +4°C+4 to +5°C
Winter rainfall+10%+20%+20%
Summer rainfall-40%-30%-10%
Winter wind speed-0.4m/s+0.2m/s+0.4m/s
Summer wind speed-0.6m/s-0.4m/s-0.2m/s
Daily temperature (min/max) – winter+3.0°C+3.0°C
Daily temperature (min/max) – winter+4.5°C+4.5°C

In the next 12 months, we will test thousands of weather scenarios for our WRMP, including the impact of a high scenario. This assumes a 5°C increase by 2100 on our supply capabilities. A complicated hydrological assessment of the process of turning rainfall into flow will be undertaken to understand the impact on water resource levels. Across the 10,000 climate change projections investigated, we take a well-balanced distribution to narrow these down to 100 scenarios. They are then put through our rainfall runoff model so we can understand the impact on supply from the amount of water available year on year. We work closely with the Environment Agency and leading experts to select the most appropriate scenario to use in planning. The uncertainty brought from the other scenarios is then analysed and included in our headroom calculations, thus ensuring we can quantifiably understand the levels of risk in our available water supply.

As always there is stringent governance to ensure these projections are correctly developed and used. Internal, external and regulator audits are undertaken to ensure we use these projections in line with UK Water Industry Research (UKWIR) best practice and Defra guidelines.

The next 12 months are critical for DWMPs as we complete and publish the outputs of our Baseline Risk and Vulnerability Assessment. This will be the result of modelling our systems and applying several impacts, including climate change, to determine future performance and risks associated with that performance.

Model updates currently in progress (2020) to understand the climate change impact of service delivery for drainage and wastewater

ModelClimate change impactRisk and performance level assessment
Hydraulic network modelsRainfall scenarios alongside future population change and urban creepFuture hydraulic flooding performance
Asset risk projection model (Pioneer)Apply climate change impacts via changes in blockage ratesFuture flooding and pollution performance with optimised system recommendations for asset interventions
Wastewater treatment works modelChanges to permit limits based on environmental models (rainfall and temperature)Future likelihood of wastewater treatment works compliance
Source Apportionment
Input models using rainfall impacts on increasing river levels alongside temperature increasesFuture water quality in the receiving water course informing the risk in achieving future permit limits

This assessment will allow us to understand, for our base-allowed investment, the levels of service expected. Coping with 3°C will require higher levels of investment than coping with 1.5°C and so, if that were to become the likely scenario, we would need to engage with stakeholders on the appropriate sharing of that cost between generations of customers.

With this understanding, a primary objective of our adaptation strategy is to prioritise interventions that deliver resilience for all climate variables. For example, reducing leakage and encouraging lower water consumption will create headroom within our supply-demand balance and provide an increasingly resilient service. This is especially important as changing rainfall patterns will affect the rate at which our reservoirs refill. Similarly, encouraging more sustainable drainage and reducing surface water into combined sewer systems will help reduce the impact of variations from future storm intensity, and frequency, on performance for customers and the environment.

A further objective of our adaptation strategy is to address the transitional risks we have as an energy intensive business, including those resulting from decarbonisation and exposure to additional taxation. Our energy strategy is focused on using less and generating more. This year we generated 191 Gigawatt hours (GWh), equivalent to almost a quarter of the electricity we consumed.

Future contributions to limiting global temperature rise to 1.5°C – a science-based target

Our emissions reduction strategy is focused on scope 1 and 2 emissions (see 'greenhouse gas emissions by scope' in Our approach to climate change). We have committed to achieve science-based targets, based on the Paris Agreement's highest level of ambition, to limit global temperature rise to 1.5°C above pre-industrial levels. This is in line with the SBTi Criteria and Recommendations(1) guidance on the most recent emissions scenarios, policies and greenhouse gas accounting standards.

SBTi guidance requires a medium and long-term target to be set based on those global temperature limiting ambitions. It requires a new baseline to be set from the most recent year for which data is available, which for us is 2019/2020.

We have committed to a medium-term target for a further 42 per cent reduction in emissions by 2030 from a new 2019/20 baseline. The science-based approach presents a target of a 100 per cent reduction by 2050.

We share the water sector's ambition to achieve net zero emissions by 2030 and this is likely to require purchasing some carbon offsets given the challenge to eliminate wastewater treatment process emissions. Our strategy accommodates the different accounting rules for purchasing offsets. Under the guidelines set by the SBTi, purchased offsets are not permitted in the delivery of any science-based targets, so these will not be an option for our 2030 and 2050 science-based target commitments. However, in delivering the sector commitment of net zero by 2030, purchase of offsets are permitted and will therefore be assessed alongside other strategic options.

(1) Science Based Target initiative Criteria and Recommendations Version 4.0

Co2 emissions Chart

Carbon dioxide


Nitrous oxide

Net GHG emissions S1 + S2 + S3

Net GHG emissions S1 + S2

SBT trajectory 1.5°C scenario

Science-based target: 42% reduction from the new 2019/20 baseline

If we hit this target we will have reduced our emissions by 85% from the previous 05/06 baseline

Our climate change mitigation strategy

Our strategy to deliver these science-based targets covers three key areas: to optimise energy consumption; generate more renewable energy; and lower our emissions. Our work to reduce emissions includes: wastewater process and storage; sludge process; biogas use and sludge disposal; fleet fuel and management; fuel use; renewable energy; land use; natural capital; and waste and resources. Our current strategy is summarised in a series of six pledges:

Our pledges to reduce our carbon footprint

Renewable energy pledges

The chart below sets out the key areas of our strategy and the contribution they make in delivering our science-based target to limit global temperature rise to 1.5°C above pre-industrial levels. The data presented shows scope 1 and scope 2 emissions.

Net greenhouse gasses

Next year, we will focus on reducing scope 3 emissions(1). This will cover influencing emissions of employees, commercial partners and suppliers and emissions of customers. Further, we will develop future standards, technologies, markets and financial solutions to support the delivery of our net zero ambition with a further commitment to set a science-based scope 3 target by 2021.

(1) The Greenhouse Gas Protocol classifies scope 3 emissions as indirect upstream and downstream emissions that occur in the value chain of the reporting company.