The Urban Heat Island Effect in Barcelona: How Climate Change is Reshaping the City

dorottyanvisionfac
Jul 8
4 min read

Updated: Aug 19

Barcelona is known as one of the most beautiful cities in the Mediterranean. It’s rich in culture, has stunning and unique architecture, and its atmosphere quickly wins people's hearts in a second. However, the city is constantly struggling with environmental challenges, known as the Urban Heat Island (UHI) effect.

The consequence of climate change and urban development is that significant temperature increases are being experienced and felt. This threatens public health, energy systems, and overall livability.

What Is the Urban Heat Island Effect?

Sunset over Barcelona skyline, featuring prominent statue, historic buildings, and distant mountains. Warm, golden hues create a serene mood.

But what is UHI? It is an effect that occurs when the air in cities, urban areas feels much warmer than in rural areas due to various human activities and built-up, congested environments.

Because, asphalt, concrete, and metal absorb and retain heat. And the absence of plants is noticeable because natural cooling and evaporation are reduced. And here in Barcelona, the phenomenon is exacerbated by the compact urban form and the limited green space in the central districts. And the frequency of heat waves is constantly increasing.

Rising Temperatures and Local Climate Data

If you look at the local climatic data, here in Barcelona, we are seeing a significant rise in temperature.

Statistics and projections show, there will be an increase of up to 2.8-3.2% by 2050. Assuming the worst-case scenario. The number of hottest days (above 30°C) is expected to increase by about 20 per year, which is very significant.

This will have an impact on different vulnerable groups, such as the elderly and children. Night-time temperatures are a particular hotspot. According to the Urban-CLIMPLAN project, night-time UHIs are even more pronounced here because the city simply cannot cool down after sunset. This sustained heat can lead to tropical nights (when temperatures remain above 20°C).

Neighborhood Disparities in Heat Exposure

However, exposure to heat is different in every area of the city. Studies have shown that Les Corts, Eixample Esquerra, Nou Barris, and Ciutat Vella have the highest daytime temperatures. Because of the dense housing and limited vegetation.

At the same time, neighbourhoods near the coast can enjoy the cooling effect of the sea during the day. On the other hand, the heat can last longer at night. Social and economic factors also play a role because the lower-income neighborhoods don’t have enough green spaces and are more likely to have poorly insulated buildings.

Expert Insights and Research Initiatives

The Centre for Land Valuation Policy (CPSV UPC) has identified the main drivers of the Barcelona UHI effect:

Urban morphology and density
Impervious surfaces
Lack of vegetation
Choice of materials by the construction industry

There is a project called CALOR, which is a citizen science initiative that enables residents to collect data on temperature and humidity in their neighbourhoods. This grassroots approach raises awareness and also provides useful information for policymakers by highlighting hyperlocal heat-sensitive points, so it is crucial.

Barcelona’s Response: Green Infrastructure and Urban Planning

However, Barcelona's government is not standing still. The city has launched a number of plans to mitigate the impact of the UHI and adapt to climate change.

Barcelona Climate Plan

The plan focuses on how to make the city more adaptable and resilient. To reduce greenhouse gas emissions by 50% by 2030 and to achieve some form of climate neutrality by 2050, this is the main objective.

Green infrastructure and Biodiversity Plan

Barcelona is working on a plan to expand its green network by adding 160 hectares of green space, increasing ecological connectivity, and promoting biodiversity. This particular plan will include using green corridors, integration of green roofs and walls, and urban forests.

Climate Shelters in Schools

The main objective is to transform schoolyards into climate shelters using blue (water), green vegetation, and grey (permeable materials) infrastructure. These spaces can be suitable during heat waves, serving as community centres.

Tree Master Plan

Barcelona is seeking to diversify its urban tree stock to improve shade and reduce allergy problems. The aim is that no single tree species should exceed 15% of the total tree stock.

Bright sun illuminating fluffy clouds against a vibrant yellow-orange sky, creating a warm and serene atmosphere. No text present.

Urban Design Innovations

Urban planning is being rethought primarily from a climate perspective. The 'Local and Interior Spaces programme (PEPI)’ focuses on transforming underused spaces such as courtyards and rooftops into green, shaded areas. New developments will be required to comply with zero-emission quotas. Public spaces should be equipped and redesigned with cool materials, shading structures, and evaporative cooling features.

Conclution

In summary, Barcelona takes a multi-faceted approach. The community engagement, scientific and policy innovation, can be a model for other cities in similar situations, having problems with UTI.

At the same time, the challenges remain, and in the coming decades, it will be crucial to drive change, maintain momentum, and scale up projects across the city.

After all, the city's approach and solutions to warming will determine the health and well-being of local residents, as well as the public mood. Dealing with urban heat is not just about temperature. It's also about adaptability, equity, and coming together in a changing world.