El Nino Returns, Japan Braces for Extreme Heat Waves

The El Nino phenomenon has returned for the first time in two years and is feared to develop into a ‘super El Nino’, potentially increasing the risk of extreme heat waves in Japan despite the pattern typically being associated with cooler summers. Experts warned on Saturday that severely high summer temperatures could once again degrade the quality of Japanese rice this year, as occurred during the El Nino event of 2023–2024. Those conditions have led farmers to begin switching to more heat-tolerant rice varieties after heat damage to the 2023 harvest triggered shortages and price surges. El Nino occurs when sea surface temperatures in a monitoring zone off the coast of Peru remain at least 0.5 degrees Celsius above baseline for more than six months. Meteorologists categorise the phenomenon as a super El Nino when the temperature rise reaches at least 2 degrees Celsius. Since 1949, only five out of 19 El Nino events have reached that threshold, and experts predict such conditions could begin this month. Under normal El Nino conditions, weakened convective activity near the Philippines prevents the Pacific high-pressure system from extending far north, typically increasing cloud cover around Japan and resulting in cooler summers. This year, however, experts expect warm waters around the Philippines to sustain convective activity, allowing the Pacific high-pressure system to move further north. They also anticipate a northward shift of westerly winds, making it easier for warm air from the south to envelop Japan. Weather forecasts indicate that temperatures during the July-to-September period are expected to be above average in western and eastern Japan, as well as in the southern Okinawa and Amami islands, while northern Japan is likely to experience near or slightly above-average temperatures. If extreme heat waves occur, they could disrupt crop growth and reduce agricultural yields. Mie University meteorology professor Yoshihiro Tachibana noted that average monthly sea surface temperatures during the previous El Nino rose by up to 2.3 degrees Celsius, contributing to the decline in rice quality that summer. Rice farmer Koji Nishimoto, 42, in Matsuyama city said he began planting the heat-tolerant ‘Niji no Kirameki’ variety this year. ‘I am worried about the extreme heat, but there is not much I can do. Farmers around me are also starting to switch to other varieties,’ he said. Ryota Kaji, head of the Rice Breeding Group at Japan’s National Agriculture and Food Research Organisation, which developed the variety, said adoption of heat-tolerant strains is proceeding faster than expected. ‘The spread is happening more widely than we anticipated. That may indicate many producers are facing difficulties due to extreme heat,’ he said. Tachibana also cautioned that the impact of warming threatens not only rice production but also other agricultural commodities and the fisheries sector. ‘It is important for us to become increasingly aware of warming triggered by extreme weather. In addition to adjusting our lifestyles to heavy rain and extreme heat, we also need to change our actions, such as striving to reduce carbon dioxide emissions,’ he said.