Concrete, cars and a lack of greenery are ratcheting up temperatures in urban parts of Malta by as much as 11°C compared to surrounding rural areas, according to a new application.

The Urban Heat Island App, which uses satellite data to detect temperature differences, shows the disparity between rural and urban areas was around 5.8 and six degrees this summer.

But the discrepancy can be alarmingly higher, as information focusing on Gżira during July’s heatwave shows.

Data revealed that one of the locality’s main roads, Rue d’Argens, was 11°C hotter than its closest rural area Wied Għollieqa, a valley less than 500 metres away.

The application, which has been made freely available online, was launched last month by the Research Innovation Unit at the Gżira local council. The European Commission Horizon 2020 JUSTNature project is run in collaboration with the US Geological Survey (USGS) and collects data from Landsat 8 and 9 – two of NASA’s satellites that run on ESRI ArcGIS online platform.

The free application shows the island covered in patches coloured in shades of red, green, yellow and blue. The darker the red in a specific area means the hotter the area becomes when it transforms into an urban heat island. Photo: The Malta Urban Heat Island App

The application shows a map of the Maltese islands covered in patches coloured in shades of red, green, yellow and blue. The darker the red in a specific area means the hotter the area becomes when it transforms into an urban heat island.

Lead researcher Fabian Borg told Times of Malta the data is revealing some worrying trends, especially in the northern harbour district and in Valletta, and the discrepancies in temperatures, even in the same locality, are sometimes dramatic. 

“Let me give you an idea of how much the temperature differs in the same localities. Take the Empire Stadium, which is embedded in the heart of Gżira and has been long closed off to the public and become a haven for wildlife. It was usually around six degrees cooler than its surrounding streets this summer,” Borg said. 

“Dozens of air conditioning units – sometimes in the same building – hundreds of cars and thousands of people can really heat our environments up dramatically in ways we would have hardly imagined. 

The satellites are able to detect temperature discrepancies every 30 square metres. The green patches indicate significantly cooler areas that are unbuilt. Photo: The Malta Urban Heat Island App

“Temperature differences are so high that families living in urban heat islands are increasingly paying more in utility bills to cool down their homes, compared to families living outside of such urban areas.” 

This might not be much of a problem for people who can afford to pay more, he said, but it will increasingly become an unjust burden on those who are less affluent and will have to endure living in neighbourhoods that become unbearably heated up.

The data available on the application comes from two earth-observing satellites that are constantly orbiting the planet at immense speeds and pass over Malta every fortnight. They collect precise thermal data as they go. 

RIU’s collaboration with USGS and NASA for night-time data comes from the recommendation the award-winning Maltese intellectual property PHASE 1 that seeks analyses of the Urban Heat Island at night to avoid the sun’s interference.

The satellites record temperatures across the islands and can detect temperature discrepancies every 30 square metres. The data is captured by NASA and USGS and is then transmitted to Gżira’s Research Innovation Unit and mapped out onto an interactive map. 

We are using this data to reimagine Gżira with new urban planning projects that would reduce excessive heat

An urban heat island is any area where heat generated from air conditioning units, vehicles, industrial buildings and other human activity is trapped and amplified, raising the temperature of that area significantly. 

Despite its name, the phenomenon does not only occur on islands but is also common in most dense cities around the world. 

Localities that lack open spaces and have poor master planning are particularly susceptible to heating up in this way. And in localities where high apartment blocks tower over both sides of a relatively narrow road, street canyons are formed, trapping heat between the dense buildings. 

Borg said the Research Innovation Unit is also working on ‘The Digital Twin of Gżira’ – a feature that will be added to the application and will, among other things, allow prospective property buyers to calculate how much more expensive their utility bills will be if they opt for apartments in the urban heat island. 

Work is in progress on the ‘Digital Twin of Gżira’, that will serve multiple dashboards for climate change adaptation and mitigation. Photo: Research Innovation Unit, Gżira local council

Borg first began studying the phenomenon of urban heat in 2015, after he noticed that recorded temperatures during summer were almost always significantly higher than those forecast in weather reports.

Borg said the Gżira council is so far the only one that has set up a research and innovation wing specifically focused on collecting data and analysing it to find climate-related solutions for the locality.

And mayor Conrad Borg Manché, who has been particularly vocal on protecting Gżira’s environment, said much more can and must be done.

“Real, long-term solutions require that we collect accurate data, and that is why we invested in this project,” he said.

“We are using this data to reimagine Gżira with new urban planning projects that would reduce excessive heat.”

There are 5,000 parked vehicles in Gżira and another 40,000 vehicles go through the locality’s streets daily, he said, and one of the solutions is to shift almost all parking underground and use the newly acquired street space to widen the pavements and plant as many trees as possible.

“That is part of our vision for Gżira, because trees significantly cool down any environment,” he said. “I know it’s not easy and it will take time to fundamentally change our present urban planning, which was designed almost solely for cars. But we need bolder, longer-term solutions like this one if we want to see some real change in the future.”

The Malta Urban Heat Island App can be accessed on https://arcg.is/0rrPTS. And the website of the Research Innovation Unit is https://riu.gov.mt.