Why Barcelona’s rooftops could soon be painted white

Painting the rooftops of the Catalan capital could lower temperatures by up to five degrees, climate scientists say.

Why Barcelona's rooftops could soon be painted white
In 2020, Barcelona recorded its hottest year in 200 years. Scientists say painting roofs white could help lower temperatures. Photo by Josep LAGO / AFP

Barcelona’s terracotta rooftops have become as well-known as some of the city’s modernist buildings. In recent years, aerial photos taken with drones have highlighted the symmetry of the grid-like neighbourhood of the Eixample, as well as the earthy colour of the city’s buildings.

But the the way Barcelona looks from the sky could change in the near future in order to make the city more resistant to heatwaves.

Climate change researchers at the Universitat Autònoma de Barcelona (UAB) are leading a project to paint the city’s rooftops white to reduce temperatures.

A combination of painting rooftops and increasing green areas in the city from 32.5 per cent to 35.9 per cent could reduce temperatures by up to 4.7 degrees Celsius during heatwaves.

Urban building materials like concrete and brick store solar radiation throughout the day and release it slowly at night. White paint would reflect the sunlight and stop it from being absorbed by the buildings.

“In our study, we have detected an average reduction in temperature of 0.8 degrees during heatwaves, and peaks of up to four degrees lower at certain locations and during certain hours of the day,” Sergi Ventura, a meteorologist from UAB, told Euronews.

“We are collaborating with public entities such as [Barcelona’s] Urban Master Plan. They are in favour of painting roofs white. But so far nothing is being done. This is a low-cost strategy. And According to our predictions, in a city like Barcelona it would work even better than increasing green spaces,” he said.

With heatwaves becoming increasingly frequent and severe due to climate change, cities around the world are finding ways to combat the heat island effect.

The Barcelona city council also announced it will build 21 “green hubs” in the Eixample neighbourhood by 2030, as part of its  “Superbock” plans.

In 2020, Barcelona had its hottest year for more than 200 years with an average temperature of 16.8C.

Spain also marked its hottest year on record in 2020, with an average temperatures hitting 14.8 degrees celsius – around 1.7 degrees hotter than the average in pre-industrial times.

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Catalonia to impose water restrictions to fight drought

Catalonia's regional government has put 515 municipalities with 6.6 million inhabitants on high alert for drought. Here's what residents should know about water restrictions.

Catalonia to impose water restrictions to fight drought

The lack of rain and high autumn temperatures have meant that several reservoirs in the northeastern region are currently only at 33 percent capacity, resulting in Catalonia facing drought.

The Ter-Llobregat system, the Darnius and the Baodella reservoirs are all affected by the low water levels.

Restrictions on water consumption will be applied across 515 municipalities affecting 6.6 million inhabitants, the councillor for Acció Climàtica (Climate Action), Teresa Jordà, announced on Monday November 21st.  

“Tomorrow (Tuesday, November 22nd) we will declare a drought alert in the Ter-Llobregat basin. There will be 26 counties in alert,” she said in an interview with Ràdio Catalunya.  

According to the Catalan Drought Plan, the Ter-Llobregat system goes into alert when the reservoirs fall below 210 cubic hectometres. This is already happening and this Tuesday, November 22nd the Interdepartmental Drought Commission will meet to declare a drought alert.

The restrictions will come into force when the resolution of the director of the Catalan Water Agency (ACA) is published in the Official Gazette of the Government of Catalunya (DOGC), which is thought to be scheduled for the end of the week.

READ ALSO – IN PICTURES: Drought in Spain intensifies as Roman fort uncovered

What will change?  

When the restrictions have been approved, water consumption will have to be reduced for agricultural, livestock, industrial and recreational uses. Specifically, agricultural consumption must be restricted by 25 percent; for livestock by 10 percent; for industrial uses by 5 percent; for recreational uses involving irrigation by 30 percent and for other recreational uses by 5 percent.

For now, there won’t be any restrictions on the domestic supply of drinking water, but there will be a few limitations on the general public. 

  • You will not be allowed to fill your swimming pool. 
  • There will be restrictions on how much you can use to water your garden.  
  • Those who have a garden are advised to water it every other day and only during the cooler hours to ensure the survival of trees and plants.  
  • You are also not allowed to fill ornamental fountains or clean the streets with water from the general supply.
  • A maximum of 250 litres of water per day per person is set (a five-minute shower uses on average 100 litres).  

Up until now, there were 301 municipalities with water restrictions. These included areas around Llobregat Mitjà, Anoia Gaià, Empordà, the Serralada Transversal, Banyoles, Prades Llaberia and the Fluvià de la Muga, which have all been suffering from drought in recent weeks. Now the Ter-Llobregat system and the Darnius and the Baodella reservoirs have been added.  

The Ter-Llobregat system supplies drinking water to more than 100 municipalities in the Alt Penedès, Anoia, Baix Llobregat, Barcelonès, Garraf, Maresme, La Selva, Vallès Oriental and Vallès Occidental regions, with a population of around five millions of inhabitants.

The Drought Plan has been in place for over a year, as the Ter-Llobregat system was in pre-alert phase since February 2021.  

In these last nine months, the Catalan Agency of Water (ACA) has implemented measures to slow down the decline of water in reservoirs.  

According to Climate Action, the production of desalination plants has been boosted, which have gone from 20 percent to 90 percent of their capacity and have contributed more than 54 cubic hectometres to the system.

This contribution has made it possible to mitigate the decline of water levels in the reservoirs and avoid greater restrictions than currently seen.  

“If today we are at 34 percent of reserves, without the desalination plants we would have stood at 27 percent,” sources from Climate Action have stressed.