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Planet Earth is currently experiencing an unprecedented warming trend. Global average temperatures are increasing at an accelerating rate in response to greenhouse gas emissions produced by human activity. These rising temperatures, in turn, lead to the release of additional greenhouse gases (like methane), leading to positive feedback loops that threaten to make the problem worse.
This scientific consensus is based on multiple sources of evidence, all of which point to the need for rapid action. According to new research by members of the NASA Sea Level Change Science Team (N-SLCT) at the University of Hawaii at Manao (UHM), a new lunar cycle that will begin in the mid-2030s will amplify the level of sea already rising due to climate change. This will mean even more coastal flooding during high tides and coastal storms in the near future.
The study that describes their findings, titled “Rapid increases and months of extremes in projections for high tide flooding in the United States,” was published last month in Nature Climate Change. The research was led by Phil Thompson, assistant professor at the Joint Institute for Marine and Atmospheric Research at UHM, and included members of the Scripps Institution of Oceanography at UC San Diego, University of South Florida, from NASA JPL and the National Oceanic and Atmospheric Administration (NOAA).
Also known as “nuisance floods” (or sunny day floods), high tide flooding (FTH) is already a problem in many coastal cities around the world. These occur when the tides reach 0.5 to 0.6 m (1.75 to 2 ft) above the daily high tide average, resulting in inundation of shores, streets, collectors. stormwater and subsoil of coastal communities. According to NOAA reports, more than 600 of these floods occurred in 2019 alone.
Similar reports indicated that between May 2020 and April 2021, coastal communities in the United States saw twice as many HTFs as in 2000. Additionally, 14 sites along the Southeast Atlantic coasts and of the Gulf have equaled or broken their records for the number of days of HTF. by a factor of 4 to 11 from what they experienced in 2000, and the number of HTF events is now accelerating to 80% of NOAA water level stations along the eastern and southern coasts. gulf.
According to this recent study, the situation will worsen by the mid-1930s and beyond. At this point, the position and alignment of the Earth, Moon, and Sun will cause the Moon to exert increased gravitational influence over Earth’s oceans. This will more often result in high tides exceeding known flood thresholds in the United States, not to mention flooding occurring in clusters that could last a month or more.
The reason why the Moon’s gravitational pull will exacerbate sea level rise is related to the plane of the Moon’s orbit, which rotates gradually over the course of 18.6 years. The Earth’s regular daily tides are suppressed during half of this cycle where high tides are lower and low tides are higher than average. In the other half, the tides are amplified, the highs increasing and the lows decreasing.
For the purposes of their study, the research team studied data from 89 tide gauge locations in every state and coastal territory of the United States (except Alaska) and combined them with the scenarios of NOAA sea level rise, flood thresholds and how often they are exceeded. annually. They also looked at statistical representations of various weather cycles (i.e. El Niño events) and astronomical cycles.
As Thompson pointed out in a NASA press release, HTFs tend to be viewed as less of a problem than hurricane storm surges, which push high tides much higher. “It is the effect accumulated over time that will have an impact,” he said. “But if it floods 10 or 15 times a month, a business cannot continue to operate with its parking lot underwater. People are losing their jobs because they cannot get to work. Weeping sumps are becoming a public health problem.
In fact, the study shows that the combination of climate change and the Moon’s gravitational pull may mean coastal communities in the Americas, Hawaii, and Guam could face flooding every day or two. As in Alaska, only the coasts of the far north will be spared for another ten years, as the coasts of these regions increase due to long-term geological processes. As NASA Administrator Bill Nelson described in a recent NASA press release:
“Low areas near sea level are increasingly threatened and suffering due to increased flooding, and it will only get worse. The combination of the Moon’s gravitational pull, rising sea levels and climate change will continue to exacerbate coastal flooding on our coasts and around the world. NASA’s Sea Level Change Team provides crucial information so that we can plan, protect and prevent damage to the environment and to the livelihoods of people affected by flooding.
This model is the first to take into account all known oceanic and astronomical causes of flooding, and the results are projected to 2080. It is also an improvement of the High Tide Flood Tool (also developed by Thomson) which is available on the NASA Sea Level Portal team. This tool, which constitutes a resource for decision makers and the general public, will soon be updated to incorporate the results of this study.
Ben Hamlington, a researcher at NASA’s Jet Propulsion Laboratory (JPL) and co-author of the article, is also the head of NASA’s Sea Level Change Team. As he indicated, the results of the new study will be a vital resource for coastal planners in the years to come as they will need to prepare for extreme weather events in addition to further flooding.
“From a planning standpoint, it’s important to know when we’ll see an increase,” he said. “Understanding that all of your events are grouped together in a particular month, or that you might have more severe flooding in the second half of the year than the first – this is useful information. ”
Further reading: Nasa, Nature Climate Change
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