As Tokyo endures increasingly severe heat waves, a local grassroots campaign is calling for expanded urban tree coverage to provide vital shade and mitigate rising temperatures. The initiative comes amid a steady decline in tree canopy across the city, contrasting with efforts to increase green spaces seen in other major global capitals.

One of the campaign’s leaders, Kaoru Morimoto, a resident of the Nakano district in western Tokyo, voiced her concern about the dwindling shade in her neighborhood. “Everyone says the summer has become more intense,” Morimoto said, noting that awareness of Tokyo’s shrinking tree cover remains limited. Since launching the campaign last year, she and fellow advocate Susumu Nirasawa have organized expert talks, shared temperature data on social media, and petitioned the local government to set formal targets for canopy expansion. They have attracted around 30 community members to support the cause.

Data from a 2024 University of Tokyo study highlights the scope of the issue: Tokyo’s tree canopy in central areas declined from 9.2 percent in 2013 to 7.3 percent in 2022, representing a loss of approximately 12 square kilometers — an area roughly three and a half times the size of New York’s Central Park. This decline is largely attributed to the disappearance of private residential gardens, as aging homeowners sell properties and mature trees are often removed when large plots are subdivided for housing development. Narrow city streets and concerns over tree safety during typhoons also limit planting opportunities.

In contrast, major cities such as New York, London, and Paris have established ambitious goals to increase urban canopy cover, with New York aiming for 30 percent by 2040 and London targeting a 10 percent rise by 2050. University of Tokyo researcher and urban forestry expert Kinya Shiraishi emphasized the importance of trees for urban life quality, noting their role in reducing heat, lowering flood risks, and improving residents’ well-being.

Tokyo metropolitan officials acknowledged ongoing efforts to expand tree canopies, focusing on areas where wider pavements allow for safe tree growth and employing careful pruning practices. They also use a broad measure of greenery that includes farmland and grassland in the city’s outer districts. However, local observers point to overpruning and frequent administrative changes as factors contributing to canopy loss in the city center.

Horticulture expert Eijiro Fujii, professor emeritus at Chiba University, warned that without prompt policy shifts, Tokyo risks losing precious urban shade amid rising temperatures and related health risks. “Deaths from heat stroke are rapidly increasing in Japan,” Fujii said. While Nakano’s mayor has recently highlighted the importance of tree shade, neighborhood officials have yet to establish concrete canopy cover targets.

Morimoto and Nirasawa’s campaign underscores a growing urgency to address Tokyo’s urban environment as climate change drives more frequent and intense heat waves. Their grassroots efforts seek to push city authorities toward more proactive measures before the window to reverse the trend closes.