Confronting accelerating climate change: Memories of biodiversity remaining on Amami Oshima

Zeroboard Research Institute Director Tomoo Machiba

I took an early summer vacation and went to Amami for the first time. Last fall, I went to the Tokyo Metropolitan Art Museum to see a retrospective exhibition *1) of Tanaka Isson, who was hailed as a child prodigy but failed to make a name for himself in the art world, and who only gained recognition posthumously. I was fascinated by the vibrant tropical colors not usually seen in Japanese paintings.

Passing through the resort-like beaches and sugarcane fields around Amami Airport on the eastern edge, we first visited an Oshima Tsumugi workshop. The dye is made from chips of locally grown Rhaphiolepis umbellata trees, boiled in a cauldron, and then browned. The raw silk is then taken to a muddy field and dipped in the mud. The iron in the mud and the tannins in the dye cause a chemical reaction, gradually turning the silk black. This process is repeated 80 to 100 times. I also had the opportunity to try mud-dyeing noren fabric, with a veteran craftsman explaining to me the Amami dialect, which I couldn't understand at all. I was amazed to learn that this unique natural dyeing method, unique in the world, is still practiced by hand. Furthermore, the threads themselves are dyed into individual patterns before being woven. Seeing this painstaking, meticulous process, it's easy to understand why the fabric is so expensive. Ichimura also worked dyeing threads to earn a living and to pay for art supplies, and to paint.

The author experiencing mud dyeing and the finished noren curtainWe headed to Kinsakubaru Primeval Forest, located in the island's center. In anticipation of its inscription as a World Heritage Site in July 2021, the area is now restricted to certified guides and tour operators are limited in the number of vehicles allowed. Ecotourism, where visitors can enjoy observing the natural environment while protecting it, is now practiced. *2) Because of the high number of highly poisonous Habu snakes, islanders rarely ventured into the mountains, so the Habu snakes have protected the forest from humans. Looking around, the flora and fauna were quite different from those in the mainland, reminiscent of a tropical rainforest or Jurassic Park. A sudden downpour made it difficult to take photos of the giant ferns known as "hikagehengo," but the wet trees' vibrant greens made the area stand out. The beauty of the Alocasia macrocarpa (which looks very similar to taro but is inedible), which Ichimura drew and which Totoro also used for his umbrella, was truly apparent.

At the mouth of Sumiyo Bay in the southwest is the second largest mangrove forest in Japan after Iriomote Island, which you can explore by kayak. I didn't join a tour and just rented the equipment, so I leisurely stopped by the shore to look at the tiny crabs that live in the mangroves and peer at the fish in the water, and before I knew it, I was in a vast body of water that could become either a river or the sea depending on the tide.

The rhododendrons and alocasia plants in the Kinsakuhara virgin forest
We then took a 20-minute ferry ride from Amami Oshima to Kakeroma Island, which stretches from east to west and has a population of around 1,000 people, where we enjoyed scuba diving. Oshima Strait (also known as the Seto Inland Sea) has calm waves but a complex underwater topography, and it's incredibly beautiful to look up from the ocean, which is teeming with fish of all sizes, corals, and sea anemones, and watch the sunlight filtering through the rocks onto the surface of the water. While we weren't able to see them this time, the Amami star pufferfish, endemic to this area, is famous for forming geometric circles on the seabed during breeding, and in winter you can apparently swim with humpback whales.

The beach in the Saneku community on the northwestern tip of the island is a long, shallow stretch of white sand. Apparently, the water is so clear it's nicknamed "Saneku Blue." However, when I donned my snorkel and dove in, I found the coral dead and almost no fish to be seen. Last summer, due to high temperatures and fewer typhoons, the average seawater temperature rose by 1-2°C compared to the previous year, exceeding 30°C. According to field surveys, approximately 60% of the coral around Amami Oshima has bleached *3) . This is the first large-scale bleaching in 26 years, since 1998. Seeing small fish clinging to the barely colored corners of the concrete-colored coral, I realized just how important living coral is to the marine ecosystem *4) .

Tokuhama, on the southeastern tip of the island, where the final installment of the "Otoko wa Tsurai yo" movie series was filmed, has a lagoon reminiscent of the South Pacific Ocean stretching out before it. Although there were more fish to be seen there than in Miku, the coral bleaching there was also serious. A woman who runs a beach hut told me that this year, even though sea turtles have come to the beach, they have left without laying eggs. Those who live in areas rich in biodiversity and who are directly connected to nature are the ones who feel the effects of climate change firsthand every day, and will likely be the ones to suffer the negative effects in the future.

There is also no end to the heartless acts of humans that directly disrupt the ecosystem. In July, 15 illegal insect traps, such as nets containing bananas and hung on trees, were found in the national park *5) . In May, three Chinese men were arrested for capturing approximately 5,200 land hermit crabs, a national natural monument, with the intent of selling them *6) . The number of road accident deaths of Amami rabbits, a special natural monument found only on Amami-Oshima and Tokunoshima, is expected to remain high at 163 on both islands in 2024 *7) *8) .

Tokuhama Beach and the hermit crabs I saw on the beach

In Amami, as in other regions, many old wooden houses are left abandoned and are left to decay. Yasuhiro Yamashita, an architect from Amami Oshima, has developed a social project called "Denpaku," which converts vacant houses and stores into accommodations and promotes interaction between tourists and local residents. There are two such accommodations on Kakeroma Island *9) . It has attracted attention from around the country as an example of town revitalization, and I was able to stay at one of them, even though it's on Oshima Island.

Both shores overlooking the Oshima Strait became important location during the Pacific War, and battleships of the Combined Fleet, including the Yamato and Musashi, were reportedly anchored in Satsuma Bay on Kakeroma Island. *10) The Japanese Navy deployed the Shin'yo, a wooden motorboat equipped with a bomb atop its bow, to the island for ramming attacks. Novelist Toshio Shimao served as commander of the 18th Shin'yo Special Attack Unit. The unit received orders to launch on August 13, 1945, but the war ended before the order to launch was given. Shimao married Miho, whom he met on the island, but his infidelity caused her to suffer a mental breakdown, leading to the end of their marriage. His autobiographical novel, "The Sting of Death," later became a film directed by Kohei Oguri and won the Grand Prix at the Cannes Film Festival. *11) Speaking of "Amami wives," one well-known example is Akana, who became the second wife of Saigo Takamori when he was exiled to Amami. *12)

On the last night of my stay, while listening to a live performance of Shimauta (traditional Japanese folk song) in a restaurant, I told the waiter, "I'm from Yokohama." He replied, "Actually, I used to be in Yokohama too. I was a firefighter." I learned that there are very few local members of the Yokohama City Fire Department; they come from all over the country and live in dormitories. *13) In the recent House of Councillors election, there was strong support for the "Japanese First" slogan, but I was reminded that we must not forget the fact that, due to economic disparity, not only foreigners but also people from rural areas take on low-paying, dangerous jobs in cities (and going back even further, to mass employment and the sending of surplus population overseas as immigrants), and that we must not forget the gratitude we feel for this.

Tokuhama, mentioned earlier, is known for its gigantic giant trevally, with groups of anglers arriving early in the morning and leaving by the afternoon. A woman at a beach hut (who had only ordered a canned coffee, but as I listened to her story, I was treated to fruit and horse mackerel sashimi caught by a local) lamented, "Anglers and beachgoers alike trash the beach and then leave without even seeing the island. I wish there were just a few people here, enjoying their time here at their own pace..." This may be the selfish wish of a city dweller, but I sincerely hope that Amami, which is yet to see large-scale resort development or "jungles," will be able to continue to survive without disrupting the ecosystem and the islanders' pace.

*1) Tokyo Metropolitan Art Museum "Tanaka Isson Exhibition: Paintings of Light and Soul of Amami", September 19th - December 1st, 2024 https://isson2024.exhn.jp/

*2) Amami City, Kagoshima Prefecture, "Introducing Usage Rules at Kinsakubaru,"June 1, 2025, www.city.amami.lg.jp/wnhs/kinsakubaru.html

*3) Asahi Shimbun, "60% of Amami's corals have died, the first large-scale bleaching in 26 years. High sea temperatures may be the cause,"December 14, 2024 https://digital.asahi.com/articles/ASSDF1S1WSDFDIFI00TM.html

*4) WWF Japan's survey in Yamato Village, Oshima County, conducted from April to July 2025, found some signs of coral survival and recovery, and no effects of bleaching were observed at depths of 10 meters or less. They plan to continue investigating the coral's resilience and recovery status. (Amami Shimbun, "Coral Reef Conservation Project Launched,"July 24, 2025 https://amamishimbun.co.jp/2025/07/24/57257/ )

*5) Asahi Shimbun, “Illegal insect collection traps in national parks, warnings ignored, Ministry of the Environment reports to Amami Police Station,”July 17, 2025 https://digital.asahi.com/articles/AST7J2V7ZT7JTLTB005M.html

*6) Yomiuri Shimbun, “Strange noises coming from Chinese passenger’s luggage left after check-out, some of which is a national natural monument,”May 30, 2025, www.yomiuri.co.jp/national/20250530-OYT1T50053

*7) Asahi Shimbun, "163 Amami rabbit accident deaths last year,"May 19, 2025 https://digital.asahi.com/articles/AST5L3W7KT5LTLTB002M.html

*8) FNN Prime Online, “Endangered rabbits and the most beautiful frog in Japan…Amami Oshima today, four years after being registered as a World Heritage Site,” Yahoo! Japan News, July 19, 2025 https://news.yahoo.co.jp/articles/a8a008456b06c9b784fd44b4984ba934427c2af0

*9) Denpaku website : https://den-paku.com

*10) Recommendations for Remote Island Travel: "Kakeroma Island in Satsukawa Bay, where the largest battleships in history, Yamato and Musashi, were also anchored,"April 1, 2024 https://remoteisland.info/satsukawa-kakeroma

*11) Daily Shincho, "The family's hellish journey, triggered by their own affair: How did the story of the marital hell depicted by author Toshio Shimao in 'The Sting of Death' end?", Yahoo! Japan News, May 3, 2025 https://news.yahoo.co.jp/articles/0bd436d23ed0776643fdf3fdcc0fe5a44a74601d　

*12) BUSHOO! JAPAN, "Saigo's second wife, Akana - What kind of woman was the island wife of Amami Oshima who gave birth to Kikujiro?", August 26, 2024 https://bushoojapan.com/jphistory/baku/2024/08/26/109104

*13) Approximately two-thirds of the successful candidates for the Yokohama City Fire Department's recent recruitment exam are from outside the prefecture. (Yokohama City Fire Department Recruitment Leaflet https://www.city.yokohama.lg.jp/bousai-kyukyu-bohan/shobo/saiyo/saiyou.files/0032_20230426.pdf )