Due to human-induced climate change, the number of high tide floods has been growing over the last decade. Research from NASA now suggests that in the mid-2030s, this might reach a more dangerous high as the effect of the climate crisis combine with a peculiar lunar cycle called nutation.
The Moon and the Sun exert a huge gravitational influence on the Earth – they are, for example, responsible for the tides. But the three bodies are not perfectly aligned. The orbit of the Moon is slightly inclined with respect to the orbit of the Earth around the Sun. For this reason, we don’t get eclipses every month. Nutation is also caused by this. The position of the Moon with respect to the Earth’s equator changes every 18.6 years.
Over this period, the height of tides in a particular region changes. When you combine it with sea level rises and other effects of the climate crisis, you have a recipe for disaster. A paper, published in Nature Climate Change, reports that every single US coast will be affected. Many coastal communities are at risk of flooding from high tides.
The National Oceanic and Atmospheric Administration (NOAA) reported a total of more than 600 such floods in 2019 – and the data shows that it might get worse. While part of the lunar nutation cycle can easily make a tide high enough to flood towns, the rest will generate lower tides. But the effect of sea-level rise will make the highest tides more dangerous at the peak of the next cycle. And since sea levels continue to increase, by the time the tides are low again, the effect of the lunar nutation won't matter much, and they will still be much higher than today. While these floods don’t feel as dramatic as a storm surge, regular flooding can lead to equally disastrous outcomes.
“It’s the accumulated effect over time that will have an impact,” lead author Phil Thompson, from the University of Hawaii, said in a statement. “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.”
The research focused on the US coast, but it’s a global problem. Without serious interventions, the climate crisis will worsen, making these models best-case scenarios.
“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.”
NASA has a dedicated portal dedicated to monitor sea level changes.