WE are in an emergency. We need to act before it is too late. Every week, new heat records are being set in different parts of the world. The Earth is growing hotter; more so in cities. When we remove vegetation and trees and replace them with concrete, we make environments warmer. Communities surrounded by roads experience the "urban heat island" effect, where pavements absorb heat when the sun is out and then release it the rest of the day. One way to counter this is by growing shade trees and greenery on every street, creating as many green corridors as possible in every city.
Trees absorb carbon and make local environments cooler. Foliage lowers local temperatures through a process called evapotranspiration. Leaves also reflect solar energy. A scientific article confirms that adding tree canopies in cities — which cool the air and prevent pavements from absorbing heat — is one of the best weapons against global warming. The French environmental agency, ADEME, estimates that a mature tree has the same cooling effect as five air-conditioners.
We can make our cities cooler and more livable by growing shade trees on every street. People naturally prefer to walk or bike on a street with shade trees where the temperature can be two to nine degrees cooler than a street without, so how do we find the space in cities to grow more trees?
Streets occupy a very large share of the total land area in cities. It varies from place to place but look at any city map and you will find that around 10 to 20 percent of total land area is devoted to roads. When you consider land in the public realm — the area controlled either by national agencies or local governments — roads probably account for 80 percent in cities. The irony is that most of this valuable public resource — our urban road network — is today devoted to private motor vehicles, even though just a small minority (only about 12 percent of households in Greater Manila and about 5 percent nationwide) are car owners. For this reason, roads should be placed in the service of the majority who walk, cycle or use public transportation, rather than the person in a car.
Streets need to be planned or redesigned so that people who walk or cycle have a more pleasant and safe travel experience. Some streets can be pedestrianized and closed to through traffic (no motor vehicles allowed except for those of local residents). Trees can be planted along the street at regular intervals to create a continuous canopy and parts of a street can even be devoted to neighborhood food gardens. On streets where through traffic remains, sidewalks can be widened so that there is enough space for planting trees. Even if this means taking away space from cars, a tree-lined and walkable street delivers many long-term benefits for local residents and the planet.
What can national and local governments do? Trees and greenery should be an integral part of every road construction or rehabilitation project. Among the standard project outputs should be tree-shaded paths for those on foot or on bicycles. Every local government unit (LGU) planning office and every road project team should include landscape architects. They can ensure that the right species of greenery and trees are procured, planted and maintained — foliage that is at the same time functional, resilient and attractive.
The 2023 national budget provides an opportunity to implement these concepts. The planting of roadside shade trees should be included in the Department of Public Works and Highways work program. The Department of the Interior and Local Government's (DILG) Local Government Support Fund should be further expanded in 2023 with special attention to the greening of existing streets and public spaces. The 2023 budget could also finance recognition and awards programs (possibly organized by DILG and/or the Department of Environment and Natural Resources), for the best urban tree planting and landscaping efforts by LGUs.
The DILG and the National Parks Development Committee can jumpstart the expansion of green public spaces by requiring every urban barangay (village) to develop a pedestrianized street to serve as a neighborhood park where any resident, young or old, can play or exercise in a safe and comfortable outdoor environment. Design guidelines can be provided, including on how to involve local communities in planning and implementing green public spaces in their neighborhoods.
Planting shade trees on every street is not only an effective weapon against climate change, it is also a way to encourage active lifestyles and promote low-carbon travel modes. It will help us survive the climate emergency and make our cities more livable. The government needs to act decisively. We are running out of time.
Robert Y. Siy is a development economist, city and regional planner, and public transport advocate. He can be reached at [email protected] or followed on Twitter @RobertRsiy.