Measure tree shade in each neighborhood, plant first where shade is scarcest, and see every tree through to maturity
Steps to make it happen
- Cities use photos taken from the sky to check how much tree shade each neighborhood has.
- Cities make and publish a map that combines shade, summer heat, and the number of older people and children.
- Cities put the hot neighborhoods with little shade first in line for new trees.
- City officials talk with residents and decide together which streets and plazas get which trees.
- Cities set aside money for watering and care until the trees take root, along with the money for planting.
- Each year, cities count how many planted trees are growing well and tell everyone the results.
- In every neighborhood, cool shade within walking distance becomes something people can count on.
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The proposal in detail
This proposal is for cities above a certain size. It manages a city's greenery not by how many trees were planted but by where the shade is and how much of it there is. The measure is the share of the ground covered by tree leaves when seen from above, and it is measured for each small block of housing using satellite and aerial images. On top of this, the city lays summer ground temperatures and the distribution of people who are weak against heat, such as the number of older people, infants, and households without air conditioning, and works out a priority score. Each city sets a minimum shade target for every block and hands out its tree-planting budget starting with the blocks with the highest scores. A rule requires that the planting budget always include the cost of watering and pruning during the several years until the trees take root, and of replanting when trees die; projects that end with planting alone are not accepted. Tree species should not be limited to one kind, but should be a mix suited to the local climate and resistant to disease and insects. As an exception, places with little rain, or places where dense underground pipes make planting impossible, may add shade by means other than trees, such as shade roofs or trellises for climbing plants. When a large tree is cut down in a priority block, the city must first show a plan to restore the same amount of shade within the same block. On private land, the city gives seedlings and care support to homeowners and businesses who plant trees in gardens or parking lots. The measurement results and how well the targets are met are published every year in a form anyone can see.
BenefitsCool air reaches the places where heat-vulnerable people live
By measuring shade block by block and setting priorities, a limited budget can be focused on the places where the people most likely to be hurt by heat live. Instead of only busy main streets and tourist spots becoming green, coolness reaches residential areas that are usually overlooked, which helps narrow the gap in how safe people's lives are. Because the cost of care is secured from the start, fewer young trees die and go to waste, and tax money and donations are more likely to remain as real shade. Because results are published every year, residents can check the situation in their own neighborhoods and watch whether promises are kept. More shade makes life easier for people who walk to shop or go to school, and it cuts the electricity used for air conditioning. Rows of trees and small green spaces also become homes for birds and insects, and walking among greenery is said to calm the mind. The process of deciding planting places together with residents can itself give neighbors a chance to meet and grow fond of their town.
DrawbacksMore greenery could raise rents and push residents out
The point opponents raise most strongly is that when greenery makes a neighborhood more attractive, land prices and rents may rise, and the low-income people who lived there before may no longer be able to stay. The people the plan meant to protect could leave, and the cool shade could go to wealthier people who arrive later. Without other measures to stop sudden rent increases, this could even widen inequality. On cost, promising many years of care after planting is a heavy burden for local governments and may squeeze the budgets of other public services. In regions with little rain, the water given to trees competes with precious water resources. Planting trees on narrow streets means fighting for space with parking, storefronts, and underground pipes, and it also brings complaints about sweeping up fallen leaves, pollen allergies, and roots damaging pavement. Residents of neighborhoods ranked low in priority will be unhappy about being put off. In addition, measurements from aerial photos and of temperature contain errors, and deciding the order by numbers alone risks drifting away from how things actually feel on the ground.
Learn the background
In many cities around the world, summer heat is getting harsher every year. Because buildings and paving hold heat, city centers tend to be hotter than the suburbs around them, and not a few people die from heatstroke and other heat illnesses. Tree shade is one of the most familiar ways to fight heat: it blocks sunlight and releases water from its leaves, cooling the air and ground around it. But greenery in cities is not spread evenly. Many cities have been found to follow a pattern in which high-income neighborhoods have rows of street trees and large parks, while low-income neighborhoods, areas near factories, and hastily built housing areas have little shade. The people who are weakest against heat tend to live in the hottest places. Also, tree-planting efforts by governments and companies are often described by how many trees were planted, and there are cases where much of the young trees die because care after planting was not enough. To protect people from heat with limited money, we need a system that measures where shade is lacking and makes sure the planted trees grow.
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This proposal was written in Japanese by AI (claude-opus-5-5, policy version 2026-10-15d) and translated by AI (claude-sonnet-5-5). Nobody has checked the facts. Read the original (日本語) How the AI writes