Cities Plant More Trees to Curb Wild Weather, Boost Healthy Living

MANTUA, Italy—From Athens to Melbourne and Seoul to New York, major cities are increasingly turning to trees to help defend against heatwaves and floods, and to boost people’s physical and mental health, urban officials and environmental experts say.

South Korea’s capital, Seoul, recently planted more than 2,000 groves and gardens, while Melbourne, Australia, plans to nearly double its canopy cover to 40 percent by 2040. Meanwhile, Athens is looking at planting more trees to lower temperatures and protect the Greek capital from sudden downpours.

“We have real problems with urban heat islands and flash floods. We know we have to take trees very seriously, and we haven’t up to now,” said Eleni Myrivili, Athens’s deputy mayor of urban nature and the city’s chief resilience officer.

Athens is still recovering from the 2008 economic crisis and lacks the staff to maintain its trees, which include bitter orange, japonica, and Judas trees, Myrivili told the World Urban Forestry Forum, which took place in the northern Italian city of Mantua.

Milan, which plans to plant three million trees and expand its green spaces by 2030, has experienced a 2-degree Celsius temperature rise and increasing heat-related deaths in the past 20 years, as well as worsening floods, said the city’s chief resilience officer, Piero Pelizzaro.

More trees should “reduce air pollution, improve the quality of the urban space … and reduce the impact of climate change,” he told the Thomson Reuters Foundation.

“Nowadays, there’s no difference between the city’s energy consumption in the winter and summer” because of the rising demand for air conditioning, he added.

Cities in Niger and Senegal in Africa are planting trees to create jobs and provide fruit for families to eat, as well as provide much-needed shade.

Healthy Trees

Trees and green spaces lower stress levels and encourage people to exercise and socialize more, experts at the World Urban Forestry Forum said. But with urban populations projected to increase by 2.5 billion people by 2050, demand for more housing and transport is putting pressure on green spaces, they said.

And a lack of expertise, data, or the ability to attract funds means cities tend to opt for “grey” infrastructure projects over “green” ones to fulfill the same job, according to a report by New York-based 100 Resilient Cities network, published Nov. 28. That could mean building a concrete wall to protect a coastal city from flooding instead of planting mangroves, which are effective, less costly, more visually pleasing, and improve air quality, said 100 Resilient Cities, which produced the report.

“What makes nature-based solutions so appealing is that with one intervention, such as an urban forest, a city can address multiple shocks and stresses at once—from flooding and heat waves to air pollution and public health—which is something that grey infrastructure is rarely able to do,” the report said.

It isn’t just large cities that need to grow more trees, the mayor of Mantua said. The small northern Italian city that hosted the international forum is home to 50,000 people and 16,000 trees.

The city council plans to increase that to 25,000 trees by 2020, to help protect against floods and rising temperatures.

By Alex Whiting