If the moon is moving away at a distance of 1.48" per year (BBC), than wouldn't that mean the gravitational pull by the moon would weaken over time causing the tidal bulge to shrink? Thus causing sea levels to rise?

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    $\begingroup$ Well, yes, the tidal effects would lessen (to zero as the moon goes to infinity), but why would you think the mean sea level would change? The tidal "bulge" is offset by a "tidal trench" 90 degrees off. $\endgroup$ – Carl Witthoft Dec 22 '18 at 20:34
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    $\begingroup$ @CarlWitthoft - There is no tidal bulge. Like Santa Claus, the tidal bulge is a lie told to children. $\endgroup$ – David Hammen Dec 23 '18 at 5:53
  • $\begingroup$ Why do you exclude lowering or stay at an intermediate level? By the way it should set uniformally at about current base level (which is not at the same distance from the center of earth due to gravity inhomogeneities I guess). $\endgroup$ – Alchimista Dec 23 '18 at 9:24
  • $\begingroup$ @DavidHammen yeah, fine -- except of course for the Antarctic Ocean, which has no interfering land masses. But for the OP's purpose, let's just go with "There are high tides and low tides, and these [rather long-distance] distributions of sea water arise from complicated interactions with the Moon's gravitational field" $\endgroup$ – Carl Witthoft Dec 23 '18 at 19:58

You are correct in saying that the moon is receding from the Earth. However, as you can see, this rate is very very small.

1.48 inches = 0.037592 meters

The Moon is 384400 kilometers away (on average), or 384400000 meters. That means every year, the Moon's distance increases by 0.00000000009779%. That's such a small difference, it is negligible on human timeframes.

Also, although the tides would shrink, this would not mean the sea level would rise. When we refer to rising sea levels, we refer to an average rise in sea levels that have been seen across the world, mostly due to climate change. During high tide, a beach may experience 4 meter higher sea level, but at low tide, it will experience 4 meter lower sea level. If the moon doubled its distance, then gravity would be a quarter its strength (gravity decreases with the square of the distance), so you would have 1 meter above during high tide and 1 meter below during low tide. As you can see, there is still no net change in sea level, it's just that the changes between high and low tide would be smaller. Again, this is negligible on human timeframes.

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    $\begingroup$ Tidal forces follow an inverse cube law rather than an inverse square law. If it was an inverse square relationship, the Sun's influence would completely dominate over the Moon's, by a factor of 180. But because it is an inverse cube relationship, it's the Moon's influence that slight dominates over the Sun's, by a factor of two. $\endgroup$ – David Hammen Dec 23 '18 at 5:43
  • $\begingroup$ Woops, you're right. $\endgroup$ – KITTENDESTROYER-9000 Dec 23 '18 at 16:13

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