Rising temperatures and more volatile rainfall are increasing environmental and economic risks in densely populated metropolitan areas, according to a climate risk assessment of Ueno Park by HDI Risk Consulting.

The study used spatial analysis to examine how climate change could affect infrastructure, tourism and public spaces in one of Japan’s busiest urban parks, which attracts around two million visitors a year.

“Our goal is to identify climate risks with precise spatial accuracy,” said Lars Regner, head of resilience services at HDI Risk Consulting. “Ueno Park shows that local changes are part of broader climatic developments affecting entire cities. As a result, adaptations related to cooling, storm water management, and vegetation stability are required.”

Temperatures in Japan have risen significantly, reaching around 0.88°C above the 1981–2010 average by 2016. Under a business-as-usual scenario, heatwaves in Tokyo are projected to increase from 6.94 days annually in 1970 to about 21.28 days by 2050.

Heavy rainfall is also becoming more intense. Sudden, localised downpours, known as guerrilla rainstorms, are placing pressure on drainage systems and can disrupt transport and business activity beyond the immediate area.

Changes in temperature and rainfall may also affect the timing of cherry blossom seasons, a key tourism driver generating billions in revenue each year. Higher temperatures could also reduce visitor numbers and time spent outdoors, with studies indicating declines of up to 20% during extreme heat.

Johanna Rohrer, risk analyst for natural hazards at HDI Risk Consulting, said that in densely populated areas like Tokyo, the urban heat island effect acts as a systemic risk factor. “Sealed surfaces, waste heat and limited air circulation intensify heat stress. This has economic consequences: extreme heat reduces worker productivity in logistics, construction and transport, increases energy demand for cooling, and poses a serious public health risk." she said. "At the same time, business interruption risks and threats to infrastructure and supply chains are rising, putting pressure on companies and insurers. Our location-specific analyses and preventive measures help identify risks early and minimise losses.”

Tokyo has introduced measures including large-scale flood defences and around 190 km of heat-reducing road surfaces. Improved heat mapping, expanded green space and better protection of underground infrastructure could help limit future disruption.

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