Wikipedia is not a credible source. Try again.
And how isn't it? So long as each given piece of information that constitutes the article is cited, and the citation information matches from the home source, that given information is then 'correct' and therefore credible. Or are you trying to take the epistemological approach in your skepticism that nothing can be proven anyway, let alone bothered to be theorized or analyzed?
I agree with Shadow D. Darkman, the Chronoverse doesn't exactly hold true to factual science, so this thread is pointless.
Well then, don't bother to read a book, or play a game or anything else than ever again because our science in reality isn't even 'factual science.' We have perceivably closer conceptions in how natural patterns occur, but that doesn't necessitate that we have 'factual' science down pact. Many changes or inspirations to pursue truth in what we know comes often from things that don't "exactly hold true to factual science" Scientific fact =/= truth.
That being said
Just because that's how it works in our world doesn't mean Square is gonna make it that way in a Chrono game.
Fictional story basis is still going to pull similarities from what people know so that the fake-world is more acceptable, or at least easier for us to understand. Do things fall-up in Chrono Trigger as the norm? Is the sky not blue? Is there a lack of seasonal changes throughout the time periods/locations? It there some difference to how their time units are made up other than sunlight contrasted to darkness to distinguish from one day to another? What contrasts to reality we actually see are 'explainable' from the games actual facts, which is a story mechanic to place particular emphasis on events and locations. If there wasn't a comparable similarity in gravity between the Chronoverse and Earth, would the applications of have a magical floating city in the sky be the same? Or the impact of having it crash to the ground if that planet's water doesn't splash?
Lavos' impact to the planet created a change in its climate. The continual effect of that change is then probably either susceptible to the Milankovitch cycles similar to our planet (thus fluctuating the severity of the 'Ice Age') or its unnaturally maintained as a ploy used by Lavos for his impact on lifeforms. If his purposes to culminate the best DNA and evolutionary traits to himself, then creating and maintaining a particular harsh living environment for long durations certainly is a possibility. It he doesn't have a hand it in, that it isn't entirely impossible that the 'Ice Age' has lasted all those millions or years, and continue to do so. Various astrologically based cycles could reduce the noticeable presence of the Ice Age for thousands of years at a time. The pocket of time from Zeal, where it seems to be receding, to 2300 AD, where it seems to be returning (at least to me) is a span of ~10,000 years, which is an interglacial period similar in length to our own planet.
