Far East: Kumamoto and the Search for Climate Solutions

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According to the Japan Meteorological Agency (JMA), the average temperature in Japan during the summer of 2025 reached a record-breaking high, with a highest temperature of 41.8°C during August. Yet, in 2026, Japan had the first-ever five consecutive days of temperatures at or above 40°C, taking place in the Tokai region. JMA particularly pointed out that western Japan, including Kumamoto Prefecture, was expected to continue experiencing unusually high temperatures during August til September. 

Kumamoto has reportedly exceeded 40°C, and many areas that are heavily affected by the 2026 earthquake experienced temperatures near 39°C this summer. Only days after a devastating earthquake struck Kumamoto in late July, temperatures across the prefecture surged to extraordinary levels. Therefore, Kumamoto, as an example of climate-vulnerable societies, reflects the growing challenge to recover from the crisis and adapt to the pace of global warming.

Kumamoto and the 2026 Earthquake 

Kumamoto Prefecture, located in the central part of Kyushu, which is Japan's southwesternmost main island, has diverse geography with overlapping environmental and geographical risks. Around 60% of the prefecture is covered by forests, and its landscape is made of mountains, deep valleys, coastal areas, and the vast volcanic caldera surrounding Mount Aso. The east of Kumamoto is dominated by Mount Aso and one of the world's largest calderas, and the prefecture's position between mountainous interior regions and coastal plains explains its frequent exposure to natural hazards, as it’s more vulnerable to flooding, landslides, earthquakes, and volcanic hazards. 

Kumamoto sits in a seismically active part of central Kyushu. On July 28, 2026, an earthquake struck the Kumamoto region at M7.1 and maximum seismic intensity 7. Furthermore, just within the first 33 minutes, it had already recorded 8 earthquakes. However, Kumamoto continued to experience earthquakes during August. According to JMA, between August 12 and August 19, for instance, Kumamoto region had earthquakes with magnitudes around 4.9, 4.5, and 4.0. 

Yet, as residents and infrastructure continued to face the aftermath of repeated earthquakes, the threat of extreme heat made the recovery process more challenging. As extreme heat continues to test the limits of conventional adaptation in Japan, scientists are now exploring the possibility of intervening directly in the Earth's climate system.

Geoengineering research in Japan

Geoengineering, also called climate engineering or climate intervention, refers to the large-scale deliberate control or interventions to the climate system, partially aiming to to counteract human-caused climate change. These intervention efforts are usually specifically to methods that experiment the atmospheric physical and chemical processes. 

Japan has been conducting research on geoengineering and solar radiation modification (SRM). Researchers from Tokyo Metropolitan University’s Environmental Geochemistry Laboratory, for example, extensively investigate the possibility of reflecting sunlight through stratospheric aerosol injection (SAI). SAI works by starting with the release of aerosol, which are tiny reflective particles – they might come from aircraft, volcanic activity, or other delivery systems. These aerosols are able to reflect a small amount of incoming sunlight back into space, which results in less solar energy eventually reaching the earth’s surface. Specifically, scientists in Japan think SAI would work as volcanic eruptions can send sulfur dioxide high into the stratosphere, and the gas can form sulfate aerosols, which reflect sunlight and can cool the planet.

However, for East Asia, even if climate intervention could have a chance to experience less severe heatwaves, it could lead to other climate changes as well. A geophysical research, named “Impact of Stratospheric Aerosol Injection Geoengineering on the Summer Climate Over East Asia”, delves into the impacts of geoengineering like SAI. Researchers found that temperature change induced by SAI not only affects precipitation, but also it can lead to anomalous anticyclones, cyclones, and monsoons. In short, a cooler Japan made possible by geoengineering doesn’t guarantee a safer climate system. 

Limitation of Adaptation

To counter extreme heat waves, Japan has a relatively comprehensive adaptation system. Its measures include issuing heatstroke warnings early, establishing cooling centers, installing AC and encouraging people to use AC, improving insulation and building design, creating more urban green space, changing school, work, and outdoor activity schedules, and improving emergency medical responses. However, adaptation measures don’t treat the case of the rising temperatures. AC, for example, can cool down the temperature for people, but the increasing electricity demand can add pressure to the energy system. Japan, nowadays, instead of focusing on how to survive heat waves, is focusing on how one can make the world less hot. 

Japan, as a highly experienced country in risk management and disaster adaptation. In the 2024 Notre Dame Global Adaptation Initiative rankings, Japan placed 13th globally for readiness, which shows the country’s social, economic and governance capacity to fastly respond to climate-related risks. In addition, According to the World Bank's assessment of Japan's school safety program, nearly 100% of schools in Japan are categorized as earthquake-safe. 

When facing climate change and natural disaster, preparedness systems always have limits. Kumamoto illustrates why this debate between geoengineering and climate change is becoming increasingly important. One can observe a community that is already accustomed to living with seismic and other natural hazards still having to adapt to new pressures when disasters overlap. Whether geoengineering could serve as an emergency measure remains uncertain, but Kumamoto’s 2026 earthquake and extreme heat waves raise a broader question for Japan and other climate-vulnerable countries: Could the risks of geoengineering ever become more acceptable than the risks of doing nothing beyond conventional adaptation?