Global Warming and the History of the Japanese Islands

　The Japanese archipelago is located diagonally from southwest to northeast in the mid-latitude zone of the northern hemisphere, approximately from 45 to 30 degrees north latitude and 145 to 125 degrees east longitude.

   Its unique location is a natural geographic premise that has brought diverse and rich natural environments and ecosystems to this modest arc-shaped archipelago.

　The effect of this east-west and north-south spread is a difference of about 1 hour and 20 minutes in sunrise time between Sapporo and Kagoshima, and a difference of about 10 degrees Celsius in annual average temperature between Sapporo and Kagoshima. Which has a stronger influence on ecosystems? Of course, it is the average annual temperature.

　Therefore, if the northern hemisphere were to experience "warming" or "cooling," the east and west sides of the Japanese archipelago would be affected in contrasting ways. During the Jomon period, which lasted for about 10,000 years, global warming and the resulting Jomon seaward movement progressed from the early to middle periods. At the Sannai-Maruyama site, which reached its peak around 5000 B.C., Aomori Bay was just a stone's throw away. The city is blessed with an abundance of fruits and vegetables (chestnuts, acorns, chinquapin and horse chestnuts) from its broadleaf forests, as well as animal protein from seafood from Aomori Bay. However, with the double whammy of "cold weather" and "Jomon sea retreat" in the mid to late Jomon period, this "Jomon city" was abandoned due to the rapid loss of population support. The entire archipelago is also thought to have undergone a massive population shift from eastern to western Japan. This was the beginning of the Yayoi civilization.

　In the subsequent 2,000-year history of the archipelago, the late historical demographer Akira Hayami pointed out that when the entire archipelago is cold, famine is more severe in eastern Japan, and when it is warm, famine strikes western Japan. The famine in eastern Japan was caused by a lack of sunlight during the rainy season and summer, sterility of rice and crops due to cold summer, and crop failure due to disease. Famine in western Japan is caused by drought in the summer, crop failure due to lack of water, and the outbreak of insect and locust damage.

　If global warming continues and the bottom of the Peak Oil's population bearing capacity drops out, the risk of famine will increase in western Japan west of the Fossa Magna. This is the lesson from the history of the archipelago.