[Pinus]

We _have_ standardized on Earth circumferences for length, only we divide by 40 million to make the numbers more sane, and got the measurement slightly wrong!

[crote]

We should just redefine it to make the speed of light a nice even 300.000 km/s - we are so close already!

[SAI_Peregrinus]

But it's already a nice round 10m/s in base 299,792,458.

[jasomill]

Why stop there when we could just as easily redefine it to be 1 (new base unit of length)/second or 1 meter/(new base unit of time)?

[Ekaros]

How hard would it be to fix this? Could we theoretically add or subtract enough material or make whole thing slightly more dense or less dense to compensate?

[jasomill]

Per Wikipedia, the discrepancy is approximately 74 km, so digging a ditch with an average depth of approximately 74/2π ≅ 12 km around the circumference of the Earth would theoretically fix the problem.

Feasibility and geological implications are left as exercises for the reader.

Regardless, I suspect a more cost-effective fix would be to redefine the meter to be a couple "legacy" millimeters longer.