Nasa has warned that the combination of “wobbly” moon orbit and rising sea levels on Earth will create greater flood risks in the coming decade.
The space agency warned that coastal cities and towns will be particularly vulnerable to the flood risk after their research was published in the journal Nature Climate Change.
What is a ‘wobbly moon’?
The moon’s orbits around Earth aren’t always fixed, with subtle changes taking place from time to time which affect our life on Earth.
The moon’s revolutions around Earth fluctuate, or “wobble”, as Nasa describes it, with this slow wobble either suppressing or amplifying tides on Earth over an 18-year period.
During half of the cycle, high tides get higher while low tides are lower.
In the other half of the cycle, less extreme tides are recorded.
The next amplification phase will begin around 2030, and will mark the part of the cycle when higher tides are seen.
Why is this a problem for Earth?
Higher tides caused by the “wobbling” moon are expected to combine with rising sea levels on Earth to create a greater flood risk for vulnerable areas on Earth.
Nasa’s Sea Level Change Science Team from the University of Hawaii found in their study that high tides will exceed currently known flooding thresholds around the US.
The floods are expected to occur in clusters lasting a month or longer depending on what position the moon, sun and Earth are in relation to each other, as this can cause a gravitational effect on the sea.
Where will be most affected?
Nasa has said that coastal cities and towns globally may be affected by floods, including “a leap in flood numbers on almost all US mainland coastlines, Hawaii, and Guam”, they said.
“Only far northern coastlines, including Alaska’s, will be spared for another decade or longer because these land areas are rising due to long-term geological processes,” they added.
But once the moon’s next amplification phase kicks in, America will be in for “a decade of dramatic increases in flood numbers”, Nasa’s assessment has found.
Nasa said that particular alignments of the moon Earth and sun, resulting in a gravitational pull on the see, might “leave city dwellers coping with floods every day or two”.
“Low-lying areas near sea level are increasingly at risk and suffering due to the increased flooding, 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 across the world.”
“Nasa’s sea level change team is providing crucial information so that we can plan, protect, and prevent damage to the environment and people’s livelihoods affected by flooding,” he added.
Phil Thompson, lead author on the new study, said:
“It’s the accumulated effect over time that will have an impact.”
He said there’s a tendency to view high-tide floods as less serious than hurricane storm surges because there’s less water involved.
“But if it floods 10 or 15 times a month, a business can’t keep operating with its parking lot under water. People lose their jobs because they can’t get to work. Seeping cesspools become a public health issue,” he said.