Residents of Tokyo are calling for increased tree coverage as the city faces rising temperatures and declining urban greenery, a trend that contrasts with efforts seen in other major global capitals. Kaoru Morimoto, a 66-year-old resident of Nakano ward in western Tokyo, expressed concern over the shrinking tree canopy in her neighbourhood, which reduces the shade and cooling relief essential during increasingly intense summers.

Last year, Morimoto launched a grassroots campaign aimed at urging local officials to set explicit canopy cover targets. Alongside Susumu Nirasawa, 71, she organizes expert talks, shares temperature data through social media, and participates in municipal council meetings to advocate for stronger action on urban forestry. They have gathered support from about 30 local residents who are concerned about the loss of trees and the impact on public health and comfort.

Japan experienced its hottest summer on record in 2025, with climate change driving more frequent and severe heat waves. Between May and August of this year, the country reported nearly 120 heat-related deaths, while over 73,000 people sought emergency medical attention. Experts highlight urban tree coverage as a key factor in mitigating heat stress, as trees provide shade and help cool the air through evapotranspiration.

However, a 2024 University of Tokyo study found that Tokyo’s canopy cover has sharply declined in recent years. The research showed that between 2013 and 2022, the city lost approximately 12 square kilometers of tree cover—an area equivalent to three and a half times the size of New York City’s Central Park. Canopy cover in central Tokyo fell to 7.3 percent in 2022 from 9.2 percent in 2013, despite the well-documented heat challenges facing the metropolis.

By comparison, New York City currently maintains around 23 percent tree cover and has set a goal to increase that to 30 percent by 2040. London aims to increase its canopy by 10 percent from the current 20 percent by 2050, while Paris plans to expand tree coverage from roughly 18 percent. These cities view tree planting as an integral part of urban planning and climate resilience strategies.

University of Tokyo urban forestry expert Kinya Shiraishi emphasized the importance of canopy cover not only for temperature regulation but also for reducing flooding risks and improving residents’ wellbeing. Morimoto and Nirasawa have taken temperature measurements themselves, finding that shaded areas under large tree canopies were about three degrees Celsius cooler than areas shaded by heavily pruned trees.

The activists hope that by presenting such data and raising public awareness, Tokyo’s local governments will recognize the necessity of preserving and increasing urban tree cover to enhance the quality of life and adapt to a warming climate.