Aureola in Piazza Luini

"Projections show that the temperature increase in Ticino, applying both more and less restrictive measures, will still be between 1.5 and 2.0 degrees over the next 10 years. At present, the heat island area is about 34 km², or 1.2% of the canton's surface area. By 2035, this area will rise to about 108 km², or 3.8% of the canton's surface area. As a result, the surface area of heat islands will triple and occupy one third of the valley floors where settlements are located".
Felix Günther, Head of Spatial Planning, Institute of Earth Sciences - SUPSI DACD

In 2018, MeteoSwiss published a report highlighting the temperature difference between rural and densely urbanised areas. Generally, temperatures in cities are 2 °C higher, and can reach peaks of up to 6 °C higher. During the hottest summer nights, the temperature does not fall below 24-25 °C in cities. Daytime heat stress and especially night-time heat stress have a negative impact on health, sometimes with serious consequences, especially for the most vulnerable, such as the elderly and children.

In Lugano, heat stress manifests itself with ever-growing frequency and intensity. Over the period 1961 - 2020, the situation has changed substantially:

• summer days (T≥25 °C) have doubled: from 40 to >80
• tropical days (T≥30 °C) have more than tripled: from <5 to 15-20
• tropical nights (T≥20 °C) have tripled: from <5 to ~15

The increase in canicular days, observed throughout Switzerland, favours the intensification of the heat island effect. The incidence of this phenomenon is greater in densely urbanised areas, since in addition to a high degree of soil sealing, ventilation is inhibited by the presence of buildings, which also act as solar ray collectors. In Lugano, surfaces such as main roads, crossroads, car parks, squares and playgrounds with hard paving have been identified as particularly susceptible to the effect, as they are often covered with impermeable or mineral materials. These paved areas absorb much of the sun's radiation during the day and release it slowly over the course of the evening, even several hours after sunset, significantly inhibiting the natural night-time drop in temperature.

Long-term forecasts by MeteoSwiss indicate that global warming will intensify in the coming decades, with a steady increase in tropical days and nights. Therefore, effective and innovative measures for adaptation and mitigation of the effects of climate change, including urban heat islands, must be promoted.

"Creating shade in the city, planting more trees, introducing water, building the city so that you don't need to be in sun-exposed areas are the mitigation measures with immediate effect, therefore propose cool places and paths".
Felix Günther, Head of Spatial Planning, Institute for Earth Sciences - SUPSI DACD 

To counteract rising temperatures during dog days, one solution often adopted is the installation of indoor air conditioners. Although these devices are effective in lowering and regulating the temperature, they are a double-edged sword. Firstly, air conditioners use large quantities of energy. Secondly, they release significant amounts of heat into the environment, thus exacerbating the urban heat island problem. This can also trigger a vicious circle: more heat implies greater use of air conditioners, which in turn makes the outside environment even hotter, thus increasing their use, and so on.

On the other hand, the most effective and least costly measures are those that utilise the so-called 'blue-green infrastructure', i.e. water and vegetation, as they allow natural cooling through, for example, shading, evaporation and soil transpiration. With this in mind, the ideal would be to reduce impermeable surfaces to a minimum, while at the same time expanding permeable ones, thus offering the largest possible green areas, covered with trees and with water close to its natural state. Large green areas, in addition to not requiring a constant supply of electricity for their operation, are effective in lowering the temperature, generally in a range between 1 and 7 °C. Moreover, their cooling effect, in the case of large areas, also extends to the surrounding neighbourhood. Smaller green areas, instead, are able to lower the temperature by up to 3 °C. In an urbanised environment, it is not always obvious to increase the number and size of parks. Therefore to create new green areas, there would be the possibility of covering the roofs and vertical walls of buildings with vegetation blankets. In the domain of water, a measure with an important impact is the redevelopment of river and lake banks, since, firstly, it allows the population to easily access to the banks and benefit from the presence of water. Secondly, fewer obstacles favour a larger exchange of air flows, thus facilitating ventilation.

However, such measures often take a long time to implement and also not everywhere is it possible to increase green areas, encourage natural shading or provide access to water features. In situations where there is a dense urban fabric and impermeable pavement (town centre squares), technical solutions must therefore be found that do not hinder local everyday life. Immediate measures to counter the heat island effect include high-pressure misting systems such as Aureola, which lower the air temperature by a few degrees, with low energy and water consumption.

Climate change is one of today's most difficult and complex global challenges to manage. The increasing emissions of greenhouse gases, from the second half of the 19th century until today, are causing significant damage to the climate. Switzerland and Ticino are not exempt from this problem. Since 1864 the average annual temperature in Switzerland has increased by 2.0 °C and the consequences of this increase can be seen in:

• Increased frequency and intensity of heat days
• Increased intensity and frequency of precipitation
• Decrease in frost days
• Decrease in glacier volume
• Decrease in days with new snow
• Increase in the vegetation period

Forecasts for the future also indicate that in 2060, if no climate protection measures are taken, compared to the norm (i.e. conditions during the period 1981-2010) we can expect in Ticino:

• an increase in average annual temperatures of 2.3 °C
• an increase in the frequency of summer droughts, up to 15 consecutive days
• an increase in heat waves and days with temperatures above 32 °C
• an increase in rainfall intensity of approximately 44 mm, particularly in winter
• a decrease in snowy winters
• an increase in natural hazards

A summer like that of 2003, which was exceptionally hot, will therefore be the norm. The worst affected areas will be the lowlands, where most of the population resides. Moreover, warming in urban areas will be further accentuated by the heat island effect.

To prevent a further deterioration of the future conditions, the federal government signed and ratified the 2015 Paris Agreement. The aim of the agreement is to limit the global temperature increase to a maximum of 2 °C compared to the pre-industrial period (before 1864), thereby committing to reduce its greenhouse gas emissions and to develop climate change adaptation and mitigation measures.

To learn more about climate change in Switzerland and Ticino, visit the website of the National Centre for Climate Services (NCCS).

Although climate change entails a considerable number of risks and challenges, there are several possibilities for action to improve liveability in the urban environment, through small and large steps, both by the City of Lugano and by its inhabitants.

Consistent with the development lines approved by the City Council, Lugano is mobilising to implement various measures to tackle, mitigate and adapt to climate change, which will be coordinated through the Municipal Master Plan (PDCom), an instrument currently being drawn up, which will chart the course to be followed for the city's development over the next 20-30 years.

Measures of particular environmental importance include:

Increasing and enhancing the blue-green infrastructure

• Improving access to surface water resources, such as the rehabilitation of the banks of the Cassarate river and its tributaries, through the Raggio verde project
• Expanding the offer of green public spaces, such as the future Viarno park, which will be the second largest city park in terms of surface area
• Developing innovative methodologies and technologies in urban green management
• Enhancing green areas in the municipal territory through the Lugano al verde project

Energy improvements

• Development of the Municipal Energy Plan (PECo) to analyse and optimise energy consumption and CO2 emissions
• Maintenance of the Città dell'Energia label
• Development of district heating networks through AIL
• Incentives for the energy refurbishment of buildings and promotion of new buildings according to Minergie energy standards

Improvement of public transport offer and slow mobility

• Development of slow mobility through walking, cycling and bikesharing services
• Expansion of the public transport network, e.g. with the future Lugano tram-train project
• Development of the first fully electric bus line

What citizens can do
If you want to make your own contribution to sustainable and environmentally friendly development, you can follow the advice provided by Aziende industriali di Lugano and #LUGANOSOSTENIBILE, which illustrate small and large daily gestures that added together can make a difference.

• Aziende industriali di Lugano (AIL), Consumo consapevole fa rima con... risparmio! Consumare consapevolmente.
   
• Città di Lugano (2019), La politica ambientale ed energetica della Città di Lugano
   
• Gehrig, R., König, N., Scherrer, S. (2018). Städtische Wärmeinsel in der Schweiz - Klimatologische Studie mit Messdaten in fünf Städten (Report No. 273). MeteoSvizzera, Zürich-Flughafen.
   
• Grilo, F., Pinho, P., Aleixo, C., Catita, C., Silva, P., Lopes, N., Freitas, C., Santos-Reis, M., McPhearson, T., & Branquinho, C. (2020). Using green to cool the grey: Modelling the cooling effect of green spaces with a high spatial resolution. Science of the Total Environment, 724, 138182
   
• Günther, F., Cereghetti, N. & Rollandi, A. (2023). Costruire in funzione del cambiamento climatico, identificare le isole di calore. Dipartimento del territorio, Cantone Ticino.
   
• Lundgren-Kownacki, K., Hornyanszky, E. D., Chu, T. A., Olsson, J. A., & Becker, P. (2017). Challenges of using air conditioning in an increasingly hot climate. International Journal of Biometeorology, 62(3), 401–412
   
• NCCS (2021). Il cambiamento climatico nel Canton Ticino – Cosa è accaduto fino ad oggi e cosa ci attende in futuro? (Report No. 1). National Centre for Climate Services, Zürich.
   
• Piubellini, S., Solcà, L., Ribolzi, M., Scuffi, L. & Clericetti, A. (2020). Strategia di adattamento ai cambiamenti climatici – Isole di Calore. CSD Ingegneri, Lugano
   
• Rizwan, A. M., Dennis, L. Y., & Liu, C. (2008). A review on the generation, determination and mitigation of Urban Heat Island. Journal of Environmental Sciences/Journal of Environmental Sciences, 20(1), 120–128
   
• UFAM (2018). Ondate di calore in città. Basi per uno sviluppo degli insediamenti adattato ai cambiamenti climatici (Report No. 1812). Ufficio dell’ambiente, Berna
   
• Ulpiani, G. (2019). Water mist spray for outdoor cooling: A systematic review of technologies, methods and impacts. Applied Energy, 254, 113647