And human life would have evolved to withstand higher temperatures, or not exist at all.If Earth had two polar oceans, it would have no ice, higher oceans, thicker atmosphere, warmer everything, and Cat 10 canes.
If either of those statements were true then life on earth would have evolved differently, to suit the conditions.If Earth had two polar continents, two Antarcticas, it would have twice the ice, lower oceans, thinner atmosphere, colder everything, and likely Canes only up to Cat 2.
Life did evolve to suit the earth's conditions, with exceptions on the majority of the earth's surface. And now AGW is changing the conditions on the habitable portion of the earth.