Photo: High tide sunny day flooding in Miami, Florida. (Photo credit: B137, CC BY-SA 4.0, via Wikimedia Commons)

Many news outlets are reporting on a ‘new’ moon wobble that will result in an increase in coastal flooding in the coming decade. In reality, the lunar wobble is not new at all; it was first discovered in the early 1700’s. Today, scientists understand that the wobble appears on a regular schedule, and it is known to reoccur every 18.6 years. What is new is our planet’s unprecedented and rapid global climate change. This, combined with the regularly occurring moon wobble, will likely result in devastating coastal flooding around the world during the near future.

To gain an understanding of how the moon wobble will affect coastal flooding, we must recall how the moon influences our tides. The moon, in its regular orbit around the Earth, exerts a pull on our planet. This pull is gravitational in nature, and the pull is felt differently in various parts of the globe and on various objects- depending on the latitude and the nature of the object. The ocean, being a non-solid entity, is far more malleable and yielding than firm land. The seas stretch and contract under the push and pull of the gravitational forces exerted by the moon, and this produces our regular and predictable tidal process.

At times, the routine pull of the lunar gravitational force combines with other celestial influences, and a ‘spring tide’ occurs. The spring tide has nothing to do with the season of spring, but instead refers to the ‘springing forth’ of the tides. The spring tide occurs when the earth, the sun, and the moon are all in alignment- this causes a much greater than usual gravitational pull on the oceans. During this time, the regular high tides that occur twice each day will be even higher. If the spring tide is combined with other factors, the tides can become destructively high, especially during our current situation of rising sea level. Stir all these variables together, and we have a recipe for disaster when the moon wobble is added to the mix.

The next moon wobble cycle will occur in the coming decade, during the 2030’s. Scientists are warning that this natural phenomenon, combined with the other factors mentioned above, will almost certainly result in major damage to infrastructure, displacement of entire communities, and significant property damage and destruction. But how can a ‘moon wobble’ result in all these dire consequences? Let’s take a look at the moon wobble and how it will affect our tides.

During the first half of the moon wobble cycle, tides are suppressed, and are generally lower than normal. During this phase, the regular high tides will be lower than normal, and the low tides are higher than normal. However, in the second half of the moon wobble cycle, the reverse occurs: high tides are intensified, and the low tides become even lower. The difference between high tide and low tide becomes much greater. But most importantly, the high tides that will come during the second half of the moon wobble cycle will now coincide with those other factors that have already augmented high tide levels.

Rising sea levels, glacial ice melt, and changes in ocean and air currents will make this next moon wobble a dangerous brew. In recent years, the National Oceanographic and Atmospheric Association has recorded about 600 high tide floods annually. However, during the second half of the moon wobble cycle, they are predicting three to four times that many, during the 2030’s. If ever there was a good time to fortify flood protection measures, this relatively calm and quiet decade is it- the coming decade will be too late.