地球温暖化の影響で、アメリカの海岸に高波が押し寄せています。
最近、アメリカ各地を高波が襲っています。昨年１２月２８日、西海岸のカリフォルニアで防波堤を越えた波が街に進入し、街中が水浸しになりました。今年に入ってからも、１月９日、ワシントン州で高波のためフェリーが浸水し、沈没の危険がありましたが、無事帰港できました。さらに東海岸でも、１月１０日にはメイン州やニューハンプシャー州を高波が襲い、街中が浸水しました。これは、異常に発達した冬の低気圧の影響で、近年まで観測されなかった気象現象です。
気象現象の激化は地球温暖化の影響です。
カリフォルニア大学サンディエゴ校のスクリプス海洋研究所の研究結果では、地球温暖化が進行し始めた１９７０年以降、冬の平均波高が約３０センチ高くなったことが明らかになりました。さらに１９９６年から２０１６年までの間に４メートル以上の高波を引き起こした暴風雨の数は、１９４９年から１９６９年までの間の約2倍でした。気象現象の激化により、強風が吹き海の波が高くなっているようです。その結果、海岸の浸食、洪水による沿岸のインフラに被害が大きくなることが予想されました。この波に関する研究は２０２３年８月に発表されており、現在のアメリカの状況を予測していた研究とも言えます。
日本周辺海域の波も高くなっています。
アメリカの異常事態をニュースで知ってから、過去１０年の日本近海の波高について調べてみました。トップの図は、気象庁が発表している波高データを元に平均して算出しました。台風や冬型、梅雨などの影響が出にくい４月を選びました。その結果、１０年で約２０ｃｍ、波高が高くなっていました。スクリプス研究所の研究では、５０年で約３０ｃｍ高くなっていました。もちろん、日本とアメリカでは気象現象は異なります。しかし、全世界的に海の波が高くなっている事は事実の様です。東京や名古屋、大阪など、湾の奥にある大都市なら、多少の高波で浸水することは無いでしょう。また、東日本大震災後に海岸に多くの防波堤が建設され、高波の影響が出る地域は限られているかもしれません。しかし、近年は台風による風も強くなっているため、油断はできないでしょう。
波高が高くなると海洋産業にも悪影響を与えます。
波高が高くなる影響は、高波による被害が増えるだけではありません。一般に船が海上を航行する際、波の影響を受けて速度が低下します。タンカーや大型客船の燃費も悪くなり、輸送の日数も増加します。また、船体の動揺も大きくなるため、沿岸漁業の漁船や釣り船などの小型船では、船員や船上で作業をする人の危険も大きくなります。結果として、海洋産業に悪影響を与えることでしょう。今後の気象変化だけでなく、海上の波にも注意する必要があるでしょう。
#地球温暖化 #高波 #アメリカ
Due to global warming, high waves are hitting the coasts of the United States.
Recently, high waves have been hitting various parts of the United States. On December 28th of last year, waves that overtook the breakwaters of California on the West Coast entered the city, flooding the city. Even earlier this year, on January 9th, a ferry was flooded in Washington state due to high waves and there was a risk of sinking, but the ferry was able to return safely to port. Furthermore, on the East Coast, high waves hit the states of Maine and New Hampshire on January 10th, inundating entire cities. This is a meteorological phenomenon that had not been observed until recently, due to the influence of an abnormally developed winter low pressure system.
The intensification of weather phenomena is an effect of global warming.
Research by the Scripps Institution of Oceanography at the University of California, San Diego has revealed that the average winter wave height has increased by about 30 centimeters since 1970, when global warming began to advance. Furthermore, between 1996 and 2016, the number of storms that produced waves of 4 meters or more was approximately twice as many as between 1949 and 1969. Due to the intensification of weather phenomena, strong winds are blowing and sea waves seem to be high. As a result, it was expected that coastal erosion and flooding would cause significant damage to coastal infrastructure. A study on this wave was published in August 2023, and can be said to have predicted the current situation in the United States.
Waves in the waters around Japan are also getting higher.
After learning about the abnormal situation in the United States on the news, I decided to research the wave heights in the seas near Japan over the past 10 years. The top figure was calculated by averaging wave height data released by the Japan Meteorological Agency. We chose April, which is less likely to be affected by typhoons, winter weather, or the rainy season. As a result, the wave height has increased by approximately 20 cm over the past 10 years. According to a study by the Scripps Research Institute, the height of the earth has increased by about 30 cm in 50 years. Of course, weather phenomena are different in Japan and America. However, it is true that ocean waves are getting higher all over the world. Large cities located deep in the bay, such as Tokyo, Nagoya, and Osaka, are unlikely to be flooded by high waves. Additionally, many breakwaters were constructed along the coast after the Great East Japan Earthquake, and the areas affected by high waves may be limited. However, in recent years, the winds from typhoons have become stronger, so we cannot afford to let our guard down.
Higher wave heights also have a negative impact on the marine industry.
The impact of higher wave heights goes beyond just increasing damage caused by high waves. Generally, when a ship sails on the ocean, its speed is reduced by the influence of waves. The fuel efficiency of tankers and large cruise ships also deteriorates, and the number of days required for transportation increases. In addition, the movement of the ship is also increased, which increases the danger for crew members and those working on board small vessels such as coastal fishing boats and fishing boats. As a result, it will have a negative impact on the marine industry. It will be necessary to pay attention not only to future weather changes, but also to ocean waves.
#GlobalWarming #HighWave #America
