Flooding is already a known problem in many cities in the US and around the world.
The National Oceanic and Atmospheric Administration (NOAA) reported a total of more than 600 such floods in 2019. to begin a decade of dramatic increases in the number of floods, according to the first study that takes into account all known oceanic causes and astronomical for floods.
Led by members of NASA's Sea Level Change Science Team from the University of Hawaii, the new study shows that high tides will exceed known flood thresholds across the country more often. In the mid-2030s, the US coast will experience rapidly increasing high-tide flooding, when a lunar cycle will amplify the rise in sea levels caused by climate change.
Additionally, floods will sometimes occur in clusters that last a month or longer, depending on the positions of the Moon, Earth, and Sun. When the Moon and Earth align in specific ways with each other and the Sun, the resulting gravitational pull and corresponding ocean response can leave city dwellers facing flooding every day or two.
"Low-lying areas near sea level are increasingly vulnerable and suffering from increased inundation, and it will only get worse," said NASA Administrator Bill Nelson. “The combination of the Moon's gravitational pull, rising sea levels and climate change will continue to exacerbate coastal flooding on our coastlines and around the world. NASA's Sea Level Change Team is providing essential information so we can plan, protect and prevent damage to the environment and people's livelihoods affected by flooding."
"It's the accumulated effect over time that will have an impact," said Phil Thompson, an assistant professor at the University of Hawaii and lead author of the new study, published this month in Nature Climate Change. Thompson pointed out that because high tide floods involve a small amount of water compared to hurricane storm surges, there is a tendency to view them as less of a problem overall. “But if it floods 10 or 15 times a month, a business can't continue to operate with its parking lot under water. People lose their jobs because they can't go to work. Sewage pits become a public health issue."
Why would cities on coasts so widely separated begin to experience these higher levels of flooding at about the same time? The main reason is a regular wobble in the Moon's orbit that takes 18,6 years to complete. There is nothing new or dangerous about swinging; first reported in 1728. What's new is how one of the effects of the wobble in the Moon's gravitational pull — the main cause of Earth's tides — will combine with rising sea levels resulting from the planet's warming .
Halfway through the Moon's 18.6-year cycle, Earth's regular daily tides are suppressed: High tides are lower than normal, and low tides are higher than normal. In the other half of the cycle, the tides are amplified: High flows become higher, and low tides become lower. Global sea level rise pushes high tides in only one direction – up. So half of the 18.6-year lunar cycle counteracts the effect of sea level rise on high tides, and the other half enhances the effect.
(BalkanWeb)
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