VOA慢速英语--研究预计,美国沿海地区的洪水频率将从2030年起激增

A new study predicts that a changing moon cycle will increase high-tide flooding across U.S. coastal¹ areas in the mid-2030s.

The finding is based on ocean tide data collected from 89 coastal areas covering every U.S. state and territory except for Alaska. This data was examined along with flooding records and predictions for future sea level rise stretching into the year 2080.

Research results showed that the combined effects of rising sea levels linked to climate change and natural changes in ocean tides will lead to increases in coastal flooding.

The prediction was recently reported in a study in Nature Climate Change. The study was led by members of the U.S. space agency NASA's Sea Level Change Team. The lead researcher of the study was Phil Thompson, a member of the Sea Level Change Team and director of the University of Hawaii's Sea Level Center.

Thompson said in a statement he expects the biggest increases to happen along the U.S. Pacific and Gulf² of Mexico coastlines, which include Hawaii and other Pacific islands. This is important because this is where high-tide flooding goes from being mostly "a local or regional issue and becomes a national issue affecting a majority of our nation's coastlines," he said.

The researchers note that many U.S. coastal areas, especially along the Atlantic coast, are already experiencing such flooding. High-tide flooding happens when tides reach anywhere from 0.5 meters to 0.6 above the daily average high tide, says the National Oceanic and Atmospheric³ Administration (NOAA).

NOAA reported more than 600 incidents of this kind of flooding -- also known as "sunny day" flooding -- in 2019. Such activity is expected to worsen and lead to longer lasting⁴ floods as high tides increase in the future and sea levels keep rising.

Ben Hamlington was a co-writer of the study. He is with NASA's Jet Propulsion Laboratory in California and also the leader of the Sea Level Change Team. He said in a statement the findings can be an important resource for U.S. coastal planners who may be centered more on preparing for extreme events rather than more high-tide flooding. For planning purposes, "it's important to know when we'll see an increase," Hamlington said.

Thompson agrees that results of the study can be used by scientists, engineers and government officials who are used to preparing for rare, severe weather events such as a 100-year storm. "But we demonstrate that it is important to plan for extreme months or seasons during which the number of flooding episodes, rather than the magnitude, is exceptional," he said.

How the moon changes tides

The prediction of increased high tides starting in the mid-2030s is linked to a normal moon cycle. NASA says the cycle -- which affects how Earth lines up with the moon and the sun -- changes our planet's gravitational pull. This, in turn, affects ocean tides.

The cycle causes "a regular wobble in the moon's orbit that takes 18.6 years to complete," NASA explains. In half of the moon's cycle, it causes high tides on Earth to be lower than normal and low tides to be higher than normal. In the other half of the cycle, high tides get higher and low tides get lower.

Currently, NASA says the moon is in the cycle that intensifies⁵ high tides. And while there have been issues with high-tide flooding, there has not been enough sea level rise to cause high tides "to regularly top" flooding levels, the researchers said.

But the next time the cycle comes around again, in the mid-2030s, sea level rise "will have been at work" during those years, NASA noted⁶. The higher seas, combined with the new moon cycle, "will cause a leap in flood numbers on almost all U.S. mainland coastlines, Hawaii, and Guam."

Such flooding could leave people in cities dealing⁷ with floods "every day or two," the research team predicts.

Words in This Story

tide – n. the regular rise and fall in the level of the sea

episode – n. a single event or period of time

magnitude – n. the large size of importance of something

regular – adj. something that happens often

wobble – v. to move from side to side

leap – n. a sudden increase or improvement

1 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

2 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

3 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

4 lasting   

adj.永久的，永恒的；vbl.持续，维持

参考例句：

• The lasting war debased the value of the dollar.持久的战争使美元贬值。
• We hope for a lasting settlement of all these troubles.我们希望这些纠纷能获得永久的解决。

5 intensifies   

n.（使）增强， （使）加剧( intensify的名词复数 )v.（使）增强， （使）加剧( intensify的第三人称单数 )

参考例句：

• A clear atmosphere intensifies the blue of the sky. 纯净的空气使天空变得更蓝。 来自《简明英汉词典》
• Blowing on fire intensifies the heat. 吹火使热度加强。 来自《简明英汉词典》

6 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

7 dealing   

n.经商方法，待人态度

参考例句：

• This store has an excellent reputation for fair dealing.该商店因买卖公道而享有极高的声誉。
• His fair dealing earned our confidence.他的诚实的行为获得我们的信任。