The Story of Global Warming Told by the Sea: Memories of Coastal Change (2007, Wakayama to Tsugaru)

The Story of Global Warming Told by the Sea: Memories of Coastal Change (2007, Wakayama to Tsugaru)

In 2007, it became clear that the oceans of the Japanese archipelago were quietly but surely changing their appearance. Analysis by the Japan Meteorological Agency revealed that sea surface temperatures in the waters surrounding Japan were rising faster than the global average, and the effects were beginning to be deeply etched into the fishing industry and marine ecosystem. The rise in sea surface temperatures, which is particularly pronounced in winter and fall, has cast a shadow over the livelihoods of people engaged in coastal fisheries in particular.

In the Kinan region of Wakayama Prefecture, the change in sea temperature has changed the appearance of mackerel. The catch of chub mackerel, once the mainstay of the fishery, has declined, and sesame mackerel have flooded the sea in its place. In 2005, sesame mackerel accounted for 80% of Wakayama Prefecture's mackerel catch, but at half the market price of chub mackerel. Fishermen continue their daily work, bewildered and distressed by the ever-changing bounty of the sea.

In Aomori Prefecture to the north, an even harsher reality prevails in the sea. Rising water temperatures during the winter have dealt a fatal blow to nori cultivation. The once abundant cultivation areas have been devastated, and red tides, which were not supposed to occur in winter, are now occurring. In the Tsugaru Straits, an abnormal phenomenon known as "isoyaki" spread, and seaweed did not grow on the seafloor, leaving only the bare surface of the rocks as if lifeless. This phenomenon conveys the changes in the sea in a tangible way.

Off the coast of Oma, the once proudly fished cold current seaweeds, kelp and kelp of the gaga-gome type, have gradually disappeared, and warm current seaweeds have spread out to fill the gaps. These changes illustrate how the simple fact of rising water temperatures can fundamentally change the ecology of the sea and eat deeply into local fisheries and livelihoods.

Further south, in Okayama Prefecture, the warmth of the sea is also threatening to undermine nori cultivation. In a year when the winter sea recorded unprecedented temperatures, a rise in water temperature of 2.2 degrees Celsius was a matter of life and death for the aquaculture farms. The green leaves swaying between the waves did not grow as they usually do, and the voices of those who cannot harvest, cannot sell, and cannot see a way forward echoed silently along the seashore.

All these phenomena are not mere meteorological coincidences. They are the story of a chain of events in which rising temperatures spill over into the ocean, changing its structure, shaking the lives that live there, and eventually shaking human life as well. Japan's coasts are now the stage for such a story.

Related information (source):

Japan Meteorological Agency, "Long-term Trends in Sea Surface Temperature
Ministry of Agriculture, Forestry and Fisheries: "Impacts of Global Warming on Fisheries
Fisheries Research and Education Organization, "Fisheries Resources and Climate Change" (Japanese only)
Ministry of the Environment "Climate Change Impact Assessment Report (Ecosystem, Agriculture, Forestry and Fisheries)