The idea that a list of kings from 4000 years ago would encodé global climate events for over 240.000 years is completely ludicrous. Astrology has a better grounding on reality than this idea. And the fact that all lengths are multiple of 600, is even more telling knowing that they counted in base 60
Most likely explanation is we're misreading some antique number system. Our interpretation of Sumerian numbering is tentative at best. The major indicator for accuracy was that early on a few different scholars converged on the same translation for the same tablets so we trust we got it right. The mathematical and astronomical tablet texts we have of Mesopotamia, where we understand the numbering very well, are much…
There is a table of squares from ≈2500 BC https://cdli.earth/artifacts/10678 that predates the earliest known copies of the Sumerian King List by a few centuries. With completely wrong values for the numerals, the math wouldn't add up: https://saalck.pressbooks.pub/mathhistory/chapter/vat-12593/ And many later kings on the list, in particular ones where we have independent evidence from inscriptions produced during their reigns, ruled for much more reasonable periods of a few years to a few decades. It's only the earlier kings that have ridiculous numbers. And at one point the list produces a subtotal of "24510 years, 3 months, and 3 1/2 days" for the 23 kings of the first dynasty of Kish, so the durations are hardly meant to be just some vague large number. (The half-day is contributed by En-tarah-ana, for unclear reasons. https://en.wikipedia.org/wiki/En-tarah-ana )