Moon ‘wobble’ affect rising tides
GS Prelims Paper 1, GS Mains Paper 1, GS Mains Paper 3, World Geography, Geophysical Phenomena, Disaster Management
Why in news:
According to a recent study, the moon wobble phenomenon is expected to lead to more flooding here on Earth in the middle of the next decade.
What is moon wobble?
- The wobble is nothing new. It is a regular oscillation that humans have known about for centuries, and it is one of many factors that can either exacerbate rising sea levels or counteract them, alongside other variables like weather an9d geography.
- The authors of the above mentioned study aimed to untangle all of those variables in an effort to improve predictions about the future of floods. Their results underscored a basic fact separate from the movement of the moon: Our oceans are rising because of climate change.
- Rising temperatures caused by greenhouse gas emissions are not the only cause of higher flood risks, and the report explored the interplay of many variables that push and pull at ocean levels.
- But in the study, one particular variable seemed to capture outsize attention: the moon wobble. The study warned that we should expect this wobble to heighten high tides in the middle of the 2030s, but it also showed that this prediction does not apply uniformly to every coastline everywhere
There’s nothing new or dangerous about the wobble; it was first reported in 1728. What’s new is how one of the wobble’s effects on the moon’s gravitational pull — the main cause of Earth’s tides — will combine with rising sea levels resulting from the planets’ warming.
Where does this wobble come from?
- High tides on this planet are caused mostly by the pull of the moon’s gravity on a spinning Earth. On most beaches, two high tides can be seen every 24 hours. The moon also revolves around the Earth about once a month, and that orbit is a little bit tilted. To be more precise, the moon’s orbital plane around the Earth is at an approximate 5-degree incline to the Earth’s orbital plane around the sun.
- Because of that, the path of the moon’s orbit seems to fluctuate over time, completing a full cycle — sometimes referred to as a nodal cycle — every 18.6 years.
- At certain points along the cycle, the moon’s gravitational pull comes from such an angle that it yanks one of the day’s two high tides a little bit higher, at the expense of the other. This does not mean that the moon itself is wobbling, nor that its gravity is necessarily pulling at our oceans any more or less than usual.
- High-tide flooding related to climate change is expected to break records with increasing frequency over the next decade, and people who want to accurately forecast that risk have to work with a lot of noisy data, including weather patterns, astronomical events and regional tidal variation.
- The moon wobble is part of that noise, but it has always maintained its own slow, steady rhythm.
Effect of wobble
- Other variables aside, since every region is different — the effect of the wobble could cause high tide levels at a beach to oscillate by 1 or 2 inches over the course of its long cycle.
- That may sound small. But in certain situations, it can matter quite a bit.