During the summer In 2017, the tide in Honolulu rose again and again to historic heights, more than ever in the 112 years that records have been kept. Philip Thompson, director of the Center for Sea Level at the University of Hawaii, wanted to know why. “Where did this come from?” he asked. “How often will this happen? Is this our window into the future?”
What Thompson and a group of researchers discovered that the future had arrived. The summer of ’17 was a glimpse of the aquatic reality coming to Honolulu and other coastal communities. Study, published this June in Nature Climate change, they found that increasing and more frequent tides would reach the inflection point of the 2030s, especially along the West Coast and on islands like those in Hawaii, so what is labeled as “unpleasant floods“often.
“Many areas on the East Coast are already experiencing recurring impacts,” Thompson says. “In the mid-2030s, these other areas will catch up quickly. So it’s a transition from the East Coast regional issue to the national issue, where most state coasts are regularly hit by high tide floods.”
How regularly? The study, which included researchers from NASA and the National Oceanic and Atmospheric Administration, shows that floods of sunny days will accumulate in the fall, creating a nightmare for cities and businesses. The streets will be impassable, cars will be damaged in parking lots, and rainwater systems will be tightened. In addition, tidal floods also pollute local watercourses with pollutants, including oil, gasoline, trace metals and nitrogen, spawning the algal blooms they create oxygen-depleted dead zones.
Thompson notes that the tidal floods are subtle and damage the community with a thousand cuts – or, in this case, tens of days a year when coming to work or shopping for groceries becomes a hassle or even impossible. “If it happens 10 or 15 times a month, it becomes a problem,” he adds. “Business can’t keep working with underwater parking. People lose their jobs because they can’t get to work. These impacts can really accumulate quickly.”
The study contributes to the growing research of variables that cause increasing tides. Like sea level rise, tidal floods vary from place to place. Factors that increase floods on sunny days include local landslides, the effects of El Niño, the slowing of the Gulf Stream along the Atlantic coast, water temperatures and ocean vortices.
Although the role of the moon’s so-called “fluctuations” in the floods caused unpleasant headlines, this is nothing new, and the label is wrong. It’s the moon do not hesitate; its angle relative to the Earth’s equator changes so little as it orbits, something was first reported in 1728. The cycle lasts 18.6 years. Half of that time is suppressed by tides, and the other half is intensified. The effect is especially strong in places that have a single tide or a dominant tide during one day, such as much of the West Coast.
Although the lunar angle is now amplifying the tides, rising sea levels in some places have not been significant enough to cross the flood threshold. That will change during the next cycle of the 2030s, the study concludes. This higher sea level, along with the second lunar cycle, will lead to a national jump in high-tide floods, starting with what Thompson and researchers call the “year of folds.”
Those years will vary from place to place due to local variables. That means La Jolla is likely to have 15 days of flooding in 2023, 16 days in 2033 and 65 days in 2043. Honolulu predicts two days of flooding in 2033 and 65 days in 2043. In St. Petersburg, Florida, the jump is from seven days in 2023. on 13 days in 2033, and then on 80 days in 2043.