The sphere is, according to Wikipedia, a reasonably correct model for earth. But mathematically the earth is an oblate spheroid. An example of that would be smarties and M&Ms, spheres squished at the poles.
As a result of gravitation and the rotation of earth, it is about 21 km longer than the Earth’s polar radius. This is, of course, a tiny amount, but according to NASA, it is increasing at a surprising speed. Our little planet is becoming more oblate.
Why? Gravitational pull varies geographically, and are affected by a shift in mass, such as ice melting increases water in the oceans, tectonic shifts, and probably a lot more we do not understand. But it is changing. Water is on the move in a big way. This will have consequences for the rotation, and will affect the correction of time. This again affects space exploration and satellites. So you could say: climate change will alter time.
Chew on that.
Why do I bother with this ludicrously nitpicking geoscience? I am not a mathematician, astrophysicist, oceanographer, climate researcher. But ever since I discovered the problem of map projections as a child, I have scratched my head over this. I then assumed that I was too stupid to understand something that was surely simple. It is nice to know that it is incredibly complex. And that makes it endlessly fascinating.