Tokyo tree cover falls as residents seek shade targets

Tokyo residents are pressing local officials to set targets for tree canopy cover as extreme heat becomes more frequent and shade in parts of the capital declines.

Kaoru Morimoto, 66, launched a campaign in 2025 in Nakano, western Tokyo, after saying summers in her neighbourhood had become harder to endure. She and fellow resident Susumu Nirasawa, 71, organise expert talks, share temperature data and petition local council officials. Around 30 people in the community have joined the effort.

Japan had its hottest summer on record in 2025. Between May and August 2026, the country recorded almost 120 heat-related deaths and more than 73,000 people needed emergency care.

A 2024 University of Tokyo study found that canopy cover in central Tokyo fell to 7.3% in 2022 from 9.2% in 2013, a loss of 12 square kilometres. Researcher Kinya Shiraishi said canopy cover is important for urban life and can also reduce flooding risks.

Shiraishi said much of the decline came from the loss of private residential gardens, as older landowners sell properties and mature trees are often cut down when large plots are divided for housing.

A Tokyo metropolitan government official said the city is working to expand tree canopies through careful pruning on roads with wide pavements where trees can grow. The official said unmanaged trees can block traffic lights and may fall during typhoons.

Eijiro Fujii, a professor emeritus at Chiba University who specialises in horticulture, said Tokyo needed to increase canopy cover and change policy quickly. Morimoto and Nirasawa said Nakano's mayor has recently stressed the importance of tree shade, but ward officials have not yet set a canopy target.