Why does the United Nations Convention on the Law of the Sea define Japan's disappearing small island as a "reef"?

According to the United Nations Convention on the Law of the Sea, if the island "disappears", it means that Japan's territorial waters will retreat by half a kilometer, so it is defined as a reef. The disappearance of Japanese islands has caused a huge storm, not only because people are worried about the earth's climate, but also because of the definition of islands. After all, reefs are related to the area of Japanese waters.

The news that "the small island in the north of the nose disappeared" first came out at the end of last year 10. Bibei Island is located about 500 meters off the coast of Ape Chan Village in the northeast of Hokkaido. According to local residents, the northern island has existed since 1970s, but at the end of last year 10, the island was submerged by seawater. Local fishermen also said that it is impossible to confirm the existence of the island now, and fishermen can only rely on maps and experience to avoid hitting the rocks. This incident attracted great attention from Japan at that time. Last year, Japanese scientists began to suspect that the northern island had been eroded by running water for a long time and divided by waves.

When the height of the island is greatly reduced, the rising sea water will be submerged. On May 20 this year, three officials of Japan Coast Guard immediately launched the "Island Finding Plan", went to Ogasawara Island for detection, and used an ultrasonic machine to measure the water depth. During the high tide, the Japanese side confirmed that there was a submerged reef at 1 m, and said that it was necessary to confirm whether the island could surface at low tide.

If Beibi Island "can't sustain human habitation or engage in economic activities", it can't surface at low tide and can only be defined as "reef" or "stone". The "downgrade" of the island means that Japan cannot continue to claim territorial sovereignty centered on Bibei Island. Japan's territorial waters will retreat by half a kilometer. This is why Japan defines reefs.