How can we balance urbanisation with protecting the environment and quality of life?

By 2050, around 80% of the world's population will be living in urban areas. Growing urbanization, along with climate change, will have a serious impact on our life in cities in terms of air quality, warmer temperatures and higher flood risk. Cities grow faster and faster. Urban areas currently occupy 3% of the Earth's surface, but they produce around 72% of the greenhouse gases. How to reduce the environmental impact and improve the citizens' quality of life? The solutions come from nature. Scientists working at the European project Urban Greenup in Valladolid in Spain are testing nature-based solutions that could allow sustainable urban development. The key is the natural properties which can be employed to mitigate climate change. How? For example, some plants can work as thermoregulators and reduce the temperature of surroundings. For that we have solutions like green roofs, mobile vertical garden or green facades. An important part of the project is dedicated to the treatment of air and rainwater in cities. Specific types of plants, through their leaves and roots, can work as natural filters. That solution is an urban biofilter. We used to call it green chimney. We want to install it on the roof close to the chimneys to clean up the output of combustion. This system is able to mainly catch hydrogen oxide and particulate matter, the two main pollutants issued by vehicles and heating systems. The potential of nature-based systems is significant. For example, in Valladolid, a cycle lane and a green pavement could prevent the emissions of nearly 200 tonnes of CO2 and reduce temperatures by 5 degrees Celsius in the summer, but the city's configuration is a factor to deal with. We have to solve some issues. The main one is the lack of space. Then we also have problems with occupying public spaces because we have underground water pipes, electric networks and underground parking. Valladolid, Izmir and Liverpool are the three front-runner cities which are testing more than 40 nature-based methods. Liverpool is a city with huge traffic density. Solutions like arboreal interventions, for instance, are expected to reduce carbon emissions by 5.55 tonnes per year and temperatures by 2 to 4 degrees Celsius during the summer season. We have issues with air quality. In Liverpool we have a few hot spots around the city, so these trees will help us clean up with air. And these trees are just phase one. We have planted 14 trees. The plans that we have for this area is to plant more than 150 trees. That will help to clean up the air off of this area. The birthplace of the Beatles is implementing several tailored strategies such as green routes, bio-pollutant filters, pollinator gardens and sustainable drainage systems to reduce the impact of flood risks. What we are looking to do is to put these green interventions into the right places in the city. We will be monitoring air quality, water quality, biodiversity, looking at well-being, people's perceptions of the area and looking at some of the economic indicators as well. Once the whole set of nature-based solutions is validated, it will be transferred to another five cities and replicated all over the world to green up more and more of our overcrowded urban areas.