Portsmouth named UK’s most vulnerable city to extreme heat

Portsmouth faces the biggest threat from extreme heat of any UK city, with new research warning the city’s vulnerability could persist for decades.

Analysis by the Ordnance Survey, Met Office and data analysis company 4 Earth Intelligence, published by The Guardian, found that the city is currently the most heat-vulnerable of 71 UK cities assessed.

The research also suggests Portsmouth will remain at the highest level of heat vulnerability until the end of the century.

Cities can be up to 10c hotter than surrounding rural areas, with places containing the least tree cover, green space and waterways particularly vulnerable.

Concrete, asphalt, buildings and other hard surfaces absorb solar radiation during the day and release the heat slowly, creating an urban heat island effect.

The research suggests all 71 cities could reach a high level of heat vulnerability by 2040. By the end of the century, almost two-thirds could reach the most severe level.

Portsmouth is among five cities predicted to face the most severe impacts by then, alongside the City of Westminster, Plymouth, Leicester and Exeter.

Somerstown, Portsea, Southsea and Fratton have been identified as areas particularly exposed to urban heat because of their limited green space and large areas of hard surfacing.

It has also noted that areas with less green space overlap with parts of the city affected by deprivation.

The council said it had been working on heat resilience and climate adaptation for the past three years.

It said: “We’re aware of the research and recognise that extreme heat poses a growing risk for Portsmouth.

“The council has been working on heat resilience and climate adaptation for the past three years and understands that some residents are more vulnerable to the impacts of high temperatures than others.

“This is reflected in evidence gathered through our work across health, social care, and education services, and reinforces the importance of the work we’re doing to help residents, businesses and public services prepare for a warmer climate.”

Councillor Kimberly Barrett, cabinet member for climate change and greening, said: “Extreme heat is a growing challenge for cities across the UK, and Portsmouth is no exception. That’s why we’re working with residents, businesses, schools, health partners, and community organisations to make our city more resilient.

“Through initiatives such as Nature Positive Portsmouth, supported by funding from the National Lottery Heritage Fund’s Nature Towns and Cities Programme, we’re increasing green infrastructure, improving understanding of heat risks, and embedding climate adaptation into planning and decision-making.

“By taking practical action now, we’re helping Portsmouth adapt to a changing climate and build long-term resilience for the future.”

What is Portsmouth doing about extreme heat?

The council said tackling extreme heat required action from local authorities, communities, businesses and other organisations.

Measures include increasing tree planting and canopy cover, supporting greener neighbourhoods and helping schools introduce trees, shade and sustainable drainage systems.

Through Nature Positive Portsmouth, funded by the National Lottery Heritage Fund through the Nature Towns and Cities Programme, the council is also working with communities and partners to improve access to nature while increasing climate resilience.

The work includes green infrastructure plans, tree planting and sustainable drainage projects intended to provide shade, cooling and flood resilience.

The council is also working with health and social care settings to help them prepare for the effects of high temperatures on staff and service users.

Businesses are being supported through the Climate Ready programme.

Portsmouth’s Local Plan includes a target of 15 per cent tree canopy cover, in line with recommendations from Forest Research for coastal towns and cities.

However, the council said it was not setting a long-term target for a specific number of additional trees.

Instead, it said the focus was on increasing overall canopy cover and creating a resilient urban forest capable of surviving future climate conditions.

Asked about the biggest obstacles to making the city more resilient, the council pointed to the challenges created by Portsmouth’s density and geography.

It said: “As a densely populated island city, Portsmouth faces challenges around space and the existing built environment.”

It added that investment would be needed from multiple sources, alongside measures to reduce residents’ exposure and vulnerability to heat.

“However, climate adaptation is embedded across a range of council policies and projects, including planning, green infrastructure, public health and community resilience.

“Our focus is on delivering the measures that will have the greatest impact while building long-term resilience across the city.

MP warns climate impacts are already being felt

Portsmouth South MP Stephen Morgan said the research showed climate change was “clearly no longer a distant threat”.

He pointed to events seen across the city during the summer, including a critical incident being declared at the Queen Alexandra hospital and dry green spaces.

He said the consequences of climate change are “being felt here and now by people across Portsmouth.

“Across this summer, we have seen our local hospital declare a critical incident, refrigeration units at local shops breaking down with food being wasted, and green spaces turning into brown tinderboxes, with wildfire scares in Eastney.

“All of this is concerning. We know that unless we act on climate change it is only going to get worse and as the Prime Minister recently said, we cannot accept this as the new normal.

“That is why I am proud to be part of a government which is taking climate change seriously. Since taking office, Labour has secured over £100bn in clean energy investment and invested £15bn through the Warm Homes Plan to install solar panels and heat pumps.

“Only Labour can deliver the serious, practical action needed to cut emissions, lower bills and to protect Portsmouth people from the climate impacts we are already living through.

“I have one of the strongest voting records on tackling climate change and this existential threat remains a key priority for me as an MP for Portsmouth.

“Local people can be reassured that I will continue to take action on these matters locally and in Parliament.”