Lecture : Room to Breathe

concrete — בטון. urban — עירוני. urban heat island — ״אי חום עירוני״: מרכז עיר שחם יותר מהשטח הפתוח שסביבו. Holon, Seoul (בירת דרום קוריאה), Paris — שמות של ערים. building — בניין. planner — מתכנן/ת ערים. bike — אופניים.

On a hot August afternoon, Noam Levi stood at a bus stop in Holon and checked the temperature on his phone: 36 degrees. There was not a single tree in sight, only concrete, cars and a long line of tired people. "If there were a few trees here," he thought, "waiting would be half as bad." Noam, a grade 10 student, did not know it yet, but his thought lies at the heart of one of the biggest questions of our time: how should cities grow?

More than half of the world's people already live in cities, and the United Nations expects this number to reach about two thirds by 2050. Israel is a small country with a fast-growing population, and it is one of the most crowded countries in the developed world. Most Israelis live in or near a few large cities, especially in the centre of the country. Crowded cities have real advantages: jobs, schools, hospitals and culture are close together, and public transport works best when many people live near each other. But crowded cities also bring traffic, noise, high prices and, in summer, a lot of heat.

That heat is not only a matter of weather. Roads, roofs and parking lots absorb the sun during the day and release heat at night, so the centre of a city is often warmer than the countryside around it. Scientists call this the urban heat island effect. Trees are one of the simplest answers. Their shade keeps streets and buildings cooler, and they also clean the air, reduce noise and give birds a home. Studies have also linked time in green spaces with lower levels of stress.

Some cities have taken bold steps. In Seoul, South Korea, a busy road that covered a stream was taken down in the early 2000s, and the stream became a long park through the centre of the city. The planners believed that if they had kept the road, the area would have stayed grey and noisy for decades. Paris is working on the idea of the "15-minute city", where people can reach shops, schools and parks within a short walk or bike ride from home.

Of course, green cities have a price. Trees need water, which is precious in a dry country, and parks take up land that could be used for housing. Planners must constantly balance these needs. Still, the question is no longer whether cities should change, but how fast. If Noam's bus stop had been designed with people in mind, he would have waited in the shade. Perhaps, by the time he has children of his own, his city will have learned that lesson.