The sea level along the coast of Japan at record high – is warming and the Kuroshio Current in the background?

 Recently NHK News on-line reported the following:

日本沿岸の海面水位が過去最高に 背景に温暖化と黒潮か

2021年2月28日 0時43分

去年の日本沿岸の平均の海面水位は、平年と比べて8センチ余り高く、統計を取り始めてから最も高くなりました。気象庁は、地球温暖化の影響で海面上昇が進展していることに加え、特に去年は、周囲より暖かい黒潮が日本の沿岸付近を通ったことが背景にあると指摘しています。

気象庁は、北海道から九州の沿岸にある16の地点で観測された潮位のデータをもとに、年ごとに平均の海面水位を算出しています。

去年の日本沿岸の平均海面水位はこの30年間の平均と比べて8.7センチ（87ミリ）高く、統計を取り始めた1906年（明治39年）以降、最も高くなったということです。

気象庁によりますと、海面水位は10年や20年の単位で変動しているということですが、1980年以降は上昇傾向が続いていて、背景には地球温暖化の進展があるとしています。さらに去年は、黒潮が蛇行して関東や東海に接近したことから周囲より暖かく、体積の大きな海水が、沿岸の海面を盛り上げたことも影響したということです。

地球温暖化の影響で日本沿岸の平均の海面水位は今後も上昇すると予測されています。海面水位が上昇すると高潮の被害が大きくなるおそれがあるため、気象庁は今後も観測を続けることにしています。

Translation

 Last year, the average sea level off the coast of Japan was about 8 cm higher than normal, the highest since the start of collecting statistics. The Japan Meteorological Agency pointed out that, in addition to the fact that the sea level was rising due to the effects of global warming, in the background was also the effect of the  Kuroshio Current, which was warmer than the surroundings, passing through near the coast of Japan.

The Japan Meteorological Agency had calculated the average sea level every year based on the tide level data observed at different 16 points along the coast from Hokkaido to Kyushu.

The average sea level on the coast of Japan last year was 8.7 cm (87 mm) higher than the average for the last 30 years. It was the highest since 1906 (Meiji 39) when statistics were first collected.

According to the Japan Meteorological Agency, while the sea level fluctuated in 10- or 20-years unit, it had been on an upward trend since 1980, and the background was the continuation of global warming. Last year furthermore the Kuroshio current, which was warmer than the surrounding, meandered and approached the Kanto and Tokai regions . It had an effect of causing a large volume of the sea water to pile up at the coastal sea surface.

It was predicted that the average sea level along the coast of Japan would continue to rise due to the effects of global warming. If the sea level rose, the damage due to the storm surge could increase. The Japan Meteorological Agency would continue monitoring the situation.

              So, the situation is partly caused by climate change. Japan as an island country will suffer more from a rise in sea level caused by a global warming.

Note: Kuroshio Current​ is a north-flowing ocean current on the west side of the North Pacific Ocean. It is similar to the Gulf Stream in the North Atlantic. Kuroshio Current​ is part of the North Pacific Ocean gyre.