The World Bank estimates that today 4.4 billion people live in cities worldwide. By 2050, 7 out of 10 people will live in urban areas.
As a result, rural landscapes are shrinking and being replaced by cities made of concrete, glass, steel and asphalt. Transportation, energy and water infrastructures become more complicated. The use of fuel and energy increases.
Climate change is adding to this ultra-urbanisation challenge with increasing temperatures, more frequent and intense weather events, floods, droughts and sea level rise. In a recent article, the World Economic Forum said that “four out of five cities face "significant" climate hazards this year, while a quarter expects to face "high-risk" climate hazards that are more intense and frequent by 2025.”
Cities are complex systems, built to last for decades. However, climate change is forcing them to evolve quickly as it is crucial to make cities smarter, safer, more frugal while also being sustainable.
The first risk for residents is coming from extreme weather events. Heavy rains can generate quick and dangerous flooding. Their consequences are aggravated by the urban environment as it leaves little room for water to evacuate.
The second is heat, with the creation of urban heat islands. Buildings, asphalt, the waterproofing of surfaces and the lack of “green spaces” are increasing temperatures further by a few degrees compared to surrounding areas. During the day, surfaces like stone, concrete or asphalt capture the heat from the sun. At night, it is released into the atmosphere, preventing a proper cooling of ambient air. Transport and air conditioning are further adding to the problem.
To protect the population and prevent health and safety issues, mitigation measures have to be taken. Solutions exist already.
First and foremost, it is important to map and measure. Map the areas at risk of flooding, and locate the hot spots and the cooler spaces. Installing sensors across the city but also analyzing former weather patterns could help understand which areas are more at risk. In addition, Artificial Intelligence brings meaningful help in analyzing these massive amounts of data. A network and sensors provide a local view (on a sensor-by-sensor analysis) for local insights as well as a macro vision to see weather events coming, follow their paths and learn from their consequences (see Camila Auvray’s post on that topic).
Then it is time for action.
Keeping people safe is a priority for emergency management teams. They need to understand where the higher flooding risk is located. They can also benefit from real-time, ultra-local weather forecasts like the ones provided by HD Rain. Based on these forecasts, populations can receive early warnings, traffic redirected, and rescue teams be pre-positioned. Lives are saved, and assets are preserved.
Water and vegetation have a key role to play to cool air thanks to evaporation and evapotranspiration. Trees and shrubs need to be reintroduced in urban environments and green areas developed. They would also act as shade, and pollution filters and help manage runoffs.
Lighter-colour pavement and reflective roof paints can contribute to the reduction of temperature in urban heat islands.
Growing populations and larger urban areas are also increasing the need for energy. If the energy produced is coming from fossil fuels, it maximizes the consequences of climate change.
The EU agreed in October 2022, on a law banning the sale of new petrol and diesel cars by 2035. The short distances associated with living and working in cities make them especially adapted to the use of electric vehicles. This measure will help transportation drastically reduce pollution emissions in cities (and everywhere).
So far, cities had no role to play in decarbonizing electricity production. It was generated in large power plants, away from urban centres as the lack of space within the cities was an issue. The advances in renewable energy technologies and in smart grids as well as political support are now contributing to the development of more local electricity generation. It is consumed where it is produced. Citizens, municipalities, shops, and companies are using their roofs, and their parking lots to install photovoltaic panels. Energy communities are created to help provide flexibility in the system and allow citizens to play their role in the energy transition. A very vertical and centralized system is now transforming into a network of nodes.
With technological progress, the development of innovative start-ups, and the use of artificial intelligence, cities are becoming smarter and more sustainable.