LIFE: taking the heat out of city living

The ancient city of Toulouse, home to the European aerospace industry and three UNESCO World Heritage sites, is no stranger to heatwaves. In 2022 residents endured a record 24 days over 35°C, and just a year later authorities issued a red warning, with the city reaching a new high of 42.4°C.

For the 1.5 million Toulousains - many of whom work in Aerospace Valley - extreme heatwaves are more than an inconvenience. Along with other large cities, Toulouse suffers from the Urban Heat Island (UHI) effect which causes large built-up areas to be significantly warmer than the countryside around them.

That’s where the five-year, €3.8 million LIFE Green Heart project comes in, with an ambitious target to reduce the local temperature by an average 3°C during heatwaves across the 30 hectare Îles du Ramier district in the heart of the city. 

LIFE Green Heart - the name is short for Generate REsiliENt actions agaiNst the HEat islAnd effect on uRban Territory - is part of a much bigger, €100 million public-private investment to create a ‘green lung’ - a green oasis in an urban environment - which will  reduce temperatures, increase biodiversity and provide an escape from the summer heat.

‘Global warming is accentuating the urban heat island effect,’ says Thélème Auzonne, project manager at Toulouse Métropole, which is coordinating LIFE Green Heart. ‘Buildings, roads and other infrastructure absorb and re-emit the sun's heat, whereas natural landscapes such as forests and water bodies emit humidity. In Toulouse, the measured nocturnal heat island effect is already +4°C to + 6°C.’

The Îles du Ramier green lung will also provide residents and visitors alike with much-needed breathing space. However, recent research suggests that hard infrastructure such as buildings, roads and car parks are the biggest factor in creating an urban heat island. 

‘Contrary to what you might think, pollution plays almost no role in the occurrence of urban heat islands,’ says Valéry Masson, director of the urban climate research team at the French National Centre for Meteorological Research (CNRM), one of LIFE Green Heart’s project partners. ‘They are actually mainly caused by high-density housing and sealed surfaces…The midday sun delivers 800 watts per square metre. Half this energy is stored and then released by surfaces such as concrete.’

Nature-based solutions, such as removing 800 car parking spaces from the city centre and planting trees in their place, will also help remove carbon from the atmosphere. In the future, nearly five tonnes of C02 per hectare will be captured each year, compared to just half a tonne per hectare when LIFE Green Heart began in 2019.

‘The project had 100 per cent backing from all political parties,’ says Thélème. ‘The scientific evidence shows very clearly that a six degree higher temperature in the city centre could lead to double or even triple the number of tropical nights. For children and elderly people, that’s a real issue.’

LIFE Green Heart is funded through the Climate Change Adaptation and Mitigation sub-programme, which supports public authorities, NGOs and businesses to shift towards a sustainable, energy-efficient, renewable energy-based, climate-neutral and resilient economy. The 2024 call for applications for funding is open until 17 September - see here for further details on how to apply.