▲ Birds collapsed on a beach in San Diego
A massive marine heat wave (MHW) has formed in the Pacific Ocean, which is expected to have significant cascading effects on weather patterns across the globe over the coming weeks and months, the Washington Post (WP) reported on July 5 (local time).
According to the WP, this MHW covers 13.5% of the Earth's surface, stretching from the Philippines to Peru and extending north to the coasts of Hawaii and California in the United States.
In Peru, located in the Southern Hemisphere, people are flocking to the beaches despite it being winter.
An MHW refers to a phenomenon where seawater temperatures remain abnormally high compared to the same period in an average year for several days or months.
This Pacific MHW was formed by the merging of two previously separate MHWs: one that originated in the North Pacific and another developing near the equator in connection with a super El Nino.
Climate scientist Dylan Amaya, who has been closely monitoring the warming near California, said, "Warming that lasts for months can mean distinct impacts for this winter and next spring."
According to the WP, two major weather events could occur within the next two weeks in connection with this MHW.
One of them is Typhoon Bavi, the 9th typhoon of the season, which has developed in the Western Pacific.
As of the morning of July 6 (local time), Bavi is moving northwest while maintaining very strong intensity in the waters near the Northern Mariana Islands, north of Guam, and has the potential to cause destructive impacts in Taiwan and China by the weekend.
The other is the possibility of a powerful heat dome forming over the western United States in mid-July, leading to a heat wave.
A heat dome is a phenomenon where stagnant high pressure forms a hemispherical heat trap, confining hot air to the ground.
Due to this, the risk of heat waves and wildfires could increase further in the western United States, including areas north of New Mexico and Arizona where wildfires have recently been raging, U.S. Department of Defense meteorologist Eric Webb said in a recent post on social media platform X.
Following that, more extreme weather events could emerge in the fall and winter.
First, there is a possibility of significant sea-level rise near the California coast due to the combined effects of very warm Pacific seawater and storms.
Climate scientist Daniel Swain explained in a recent live stream that the probability of historically unusual or unprecedented heavy rain and storms occurring this winter has increased.
He explained that very warm Pacific seawater could raise sea levels near California by 6 inches to 2 feet (approximately 15 to 61 cm), and when combined with the wind effects from fall and winter storms, the sea-level rise near the California coast could potentially reach 2 to 3 feet or more, which is about 0.6 to 0.9 meters or more.
As the heat from this Pacific MHW is released into the atmosphere, the subtropical jet stream could strengthen from fall through winter, increasing the likelihood of heavy rain and thunderstorms not only in California but also in the southern and eastern United States.
Rising seawater temperatures increase water evaporation, raising the moisture content in the atmosphere. This increased moisture can be carried by winds circulating around high and low-pressure systems, traveling thousands of kilometers from its origin to cause heavy rainfall.
Near Europe, particularly in the Mediterranean, an MHW formed after a heat dome caused a heat wave in Europe in June. The exceptionally high water temperatures could exacerbate the extreme heat expected to last until mid-July.
Currently, more than 37% of the world's oceans are covered by MHWs.
In January 2024, when a strong El Nino was underway, more than 46% of the world's oceans were experiencing MHWs simultaneously, which was the highest level on record.
The proportion of the total ocean surface area experiencing MHWs was only about 9% in the late 1980s, but it is now over 30%, having more than tripled in about 40 years.
(Photo: AP, Yonhap News)
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