Climate change risks

Diggers building sea defences

Climate change is already here. Since the 1960s, Portsmouth has recorded:

  • An average increase of 1°C to both winter and summer temperatures
  • An average of seven less frosty days a year
  • An increase of 7% on annual rainfall, that’s an additional 50 mm of rain

Locally, we’ve already experienced:

  • Flooding from heavy rain
  • Injuries from cold snaps and heatwaves
  • Landslides
  • Tornados
  • Damaged buildings and roads
  • Travel delays
  • Disrupted public services such as refuse collection
  • Cancelled events

Portsmouth's climate change outlook

Climate models use historical data and pair that with predictions of likely greenhouse gas emissions to work out the likely future climate. Using recent averages, models predict that Portsmouth in the 2040s is likely to have:

  • Average summer maximum temperatures could be over 2°C higher than now
  • Summer rainfall could fall by 15%
  • Average winter minimum temperatures could be over 1°C higher
  • Winter rainfall could increase by 12%
  • Sea level could be 21 cm higher

The 2080s might be beyond some of our lives, but not your children’s. Using recent averages, models predict that Portsmouth in the 2080s are like to have:

  • Average summer maximum temperatures could be over 6°C higher
  • Summer rainfall could fall by 27%
  • Average winter minimum temperatures could be over 3°C higher
  • Winter rainfall could increase by 38%
  • Sea level could be 57 cm higher

Data sources: The Met Office

This means Portsmouth summers are getting progressively warmer and drier, with an increased chance of drought, wildfires, and heat stress, particularly to those who are more exposed, such as outdoor workers, or residents who are more vulnerable such as older people and babies, and those with underlying health conditions. The effects of heat will be felt most in dense urban areas of Portsmouth like Somerstown, Portsea, Southsea, Fratton where there is lots of hard surfaces and little vegetations such as trees to help cool the air. This is called the ‘urban heat island’ effect which means urban areas are often even hotter than surrounding areas.

Winters will be warmer and wetter, meaning an increased frequency and severity of flooding. An increased frequency of extreme weather events such as heatwaves, heavy rain, storms and extreme cold.

As a low-lying coastal city, Portsmouth is at risk from continually rising sea level.

Climate change impact to our environment

Plants and animals will also find it harder to live in our city. Some species might disappear, and new species might appear. Seasons might start earlier or later and our wildlife might struggle to adapt.

The impacts to us, our environment and society will be enormous if we do not reduce our emissions to avoid the worst of climate change.

Climate change resilient Portsmouth

We’ve been working hard to protect Portsmouth from the worst effects of climate change. More work will have to continue to ensure Portsmouth has a liveable future for everyone.

Reduce the urban heat island

Climate change means that across the UK our summers are getting warmer, and we are likely to experience severe heatwaves more often. In urban areas, like Portsmouth, heat is felt more because man-made surfaces like concrete hold on to the heat more easily than vegetated areas.

Through our new Greening Strategy, we will be focussing on enhancing nature in the city that helps us adapt to climate change by protecting us from flooding, storing carbon, and keep us cool in heat waves.

Protect us from sea level rise

The impacts of sea level rise on our low-lying city would be severe. That’s why we’re reinforcing our sea defences now, before there’s costly damage to our homes, businesses, and infrastructure.

Currently, nearly 13 km of sea defences are being upgraded around North Portsea and Southsea which will protect over 12,000 homes and 1,200 businesses. These efforts have been internationally showcased by the UNFCCC High Level Champions for climate change resilience.

Improve drainage

Climate change means that our winters are becoming wetter, and it’s also more likely that we’ll experience episodes of extreme heavy rainfall in summer. This is why we need to get better about managing water.

Much of Portsmouth’s wastewater network was constructed during the Victorian era and combines rainwater with household wastewater in the same pipes. During periods of heavy rain, this can lead to our drainage systems becoming overwhelmed and causing floods. Therefore, when there’s a substantial amount of rainfall, we must work to reduce and slow down the flow of water entering the drains.

One way we can do this is by allowing more water to drain into our soils and planting more vegetation. Plants not only absorb some of the water, but they also help the soil keep hold of the water, and their leaves slow down the water before it reaches the ground. Additionally, we have begun to remove paved areas in flood-prone zones and create rain gardens where rainwater can be absorbed into the soil instead of entering the drains.

You can also contribute in various ways:

  • Replace artificial grass, concrete, and paving at home with plants and natural drainage solutions. This will not only aid in drainage but will also make room nature, store more carbon, help keep you cool in the summer, provide homegrown food, and make Portsmouth a nicer place to live
  • Install water butts to collect rainwater from your roof. You can use this free water for gardening during dry periods. You can often find second-hand water butts at our Waste Recycling Centre shops

Climate change resilient council

As a public service provider, and manager of roads and lands, we need to make sure we can keep delivering to Portsmouth in all conditions. We do this by: 

  • Providing equipment to our staff to work from different locations 
  • Risk and preparedness plans to ensure our operations can continue during any poor weather conditions 
  • Making sure our buildings are prepared for extreme weather with back-up generators, and raised electrical systems 
  • Our port uses an extreme weather alert system and berths are offered to vessels needing shelter