I have heard that the land and the sea fight over territory sometimes. Long ago, the land held more, but the sea swept in to claim much of it, and it has held that territory ever since. Go down to the coast and you can see the evidence of this with your own eyes. We find the ruins of our ancestors’ world all around us, even there, now sunk beneath the waves.
Another story: long ago, as now, the elephants tended the land. They created forests and prairies, and life teemed under their watchful care. But then, they died off, and they left it to the human people to carry on their work. Humans did not have their great feet or tusks, though. Instead, they had a kinship with fire. Fire could cleanse the land just as the elephants had, and so the people turned to fire to carry on the work of the departed mammoths. Some of our ancestors understood the careful balance this required, but not all. Some burned too much, until they burned the heavens themselves. The earth baked in the heat of their fires, and cried out to the ocean. The ocean heard that cry, and rose up to extinguish the flames. Even generations later, the oceans hold onto that land to keep humans out. It sends rain down constantly and batters the shores with ceaseless hurricanes and typhoons to keep us from burning the world again. We may have learned, but the ocean and the sky have long memories, and they have not yet forgiven us. The elephants returned to take back their old tasks and to watch over us, to make sure that we did not stray again.
The elders tell us that long, long ago, before their own births even, it could become so cold that even water would turn solid and hard, like glass, and people would even die from the cold. I’ve heard that near the poles, in the darkest days of the long night, they sometimes see rain that has become solid falling from the sky in white flakes, but I have never seen it myself.
The Fifth World assumes the worst with regards to climate change: that increasing carbon dioxide sets into motion other processes like the ice-albedo feedback loop, and the release of giant pockets of methane from places like the Arctic and the ocean floor. We speculate that this causes run-away global warming, knocking the earth’s climate out of its current equilibrium and causing it to shift quickly into a new one. The heat continues to build until the current cloud regime breaks down, and a new one forms. This new cloud regime is much thicker than our current one, with the higher temperatures causing more evaporation and putting more water in the atmosphere. The thicker cloud cover finally puts a break on the runaway warming cycles as they create an albedo effect that reflects more of the sun’s rays away from the earth.
We model our expectations for the Fifth World on the Paleocene-Eocene Thermal Maximum, 55.5 million years ago, the last time that so much carbon dioxide existed in Earth’s atmosphere. As then, the Fifth World has no ice caps. In fact, snow and ice likely only appear at the poles during particularly cold winters. The amount of carbon dioxide in the atmosphere becomes the dominant factor in climate, rather than seasonality or latitude. This creates a great deal more climatological homogeneity on earth. The difference between winter and summer has greatly diminished, as has the difference between the poles and the equator. As in the Eocene, you can find palm trees and crocodiles on the shores of the Arctic Ocean, and find a scene only slightly warmer still along the shores of the Gulf of Guinea.
The new cloud regime means almost constant rain, as well as enormous storms. Tropical storms have become both bigger and more common. Earth has become a jungle planet wrapped in nearly constant cloud cover, much hotter and wetter than our current climate.
Rising levels of carbon dioxide caused the world’s oceans to become more acidic. This has led to the extinction of innumerable species of sea life, especially shellfish. Cephalopods, however — octopi, nautili, cuttlefish, bobtails, and squids — have flourished.