[Empire_of_Liberty]

I think you have the best take. If any shortening is possible, it would be from locking up large bodies of water, which wasn’t really a thing until 100 years ago.

If North and South America were ever separate, then I would think that their joining would have made quite a difference a long time ago.

[HYPOCRACY]

We may see the undoing in the not too distant future.

[Tell It Right]

I respectfully disagree. If anything, moving lots of water up vertically (by damming the water) moves mass away from the center of rotation, which provides a tendency to slow rotation, not speed it up.

As an example, the next time you take your kids or grandkids to the park and push them on the merry-go-round, do an experiment. Push it hard to get it spinning, then ask them to lean their bodies away from the center (which slows the rotation), then ask them to lean their bodies towards the center (which speeds rotation). I did this with my kids to teach them about kinetic energy and rotational inertia.