Was Rubicon 3 always frozen?

I recently replayed Attack the Dam Complex and it made think "hey, wait a minute, what do they have a dam for if everything is frozen??" Was Rubion a frozen wasteland before the Fires of Ibis, or did the Fires just really mess up the environment? I know it gets mentioned several times that Coral melts ice, so was Coral keeping the surface liquid, and the result of the Fires (barely any Coral left) what caused the water to freeze again?

Curious to hear your thoughts and insights. Thanks!