THE RULES OF THE GAME

Take a globe of the Earth. Pry it loose from its stand. Now choose new poles, anywhere you like--well, opposite each other would be smart! Drill holes at the new poles and plug the old pole-holes and put your globe back on its stand... tilted.

Now spin it. Spin it for a million years! While you contemplate the following questions:

• What happens to the climate on your new Earth? Is there land around the poles, will there be big ice caps, or just sea ice?
• What does that do to sea levels? Where will your new coastlines be, and what does that do to your continents--new lands may emerge, or old ones may break up, or have inland seas.
• Which parts of your new tilted, shrunken, flooded or enlarged continents are hot, temperate, cold?
• Latitude doesn't totally determine warmth. Where are the major currents? What coasts do they heat or cool? How high is the land, does that modify the climate?
• Where do the winds come from? Where will rain fall, where will you get deserts? (The weak dry winds around 20-35 degrees north and south, or any wind from deep inland, can mean trouble. )
• Where do mountains harvest water from sea-winds, and where do they create rainshadows?
• Will your continental interiors heat up in summer enough to create updrafts, driving monsoon winds?
• Is your climate stable? Might it fluctuate or even cycle regularly?
• Where might people evolve? From what species?
• What effects will they have on the land? Are they carnivores, will they cause mass extinctions?
• Where will your people migrate to--and how sophisticated would they have to be to get there? Where are geographic crossroads and land bridges? Where are straits that primitive rafts could cross, and where are real boats needed to reach new lands?
• Where might civilization evolve? Not just people plus a suitable land (decent climate near a crossroads where ideas, seeds and tools can be transmitted)--you also need suitable plant and animal species as raw material. What if earlier hunters extincted them all?
• If civilization rises, where will it spread and flower? Seed-beds aren't always ideal for the rise of technology later on. Will new lands outstrip the old?

Now paint your globe. Deep green jungles, olive savannas and scrublands, yellowish grasslands, green temperate forests, pine-dark subarctic forests, brown and reddish deserts, pale sand dunes, black lava fields, white ice, turquoise reefs and shallows, indigo abysses.

THE GOAL

Now step back and evaluate. Overall, are your seas and lands more or less fertile? Have you gained or lost?

You can try to maximize biomass, or biodiversity, or the most habitable land; or simply try to minimize dead or marginal lands; or even try to create the most places with conditions likely to evolve intelligent creatures--not just nature, but culture. Or you can simply aim for the strangest Earth.

Remember, you're not God. The game is TILT, not CONTINENTAL DRIFT or RANDOM WORLDBUILDING (not that those aren't fun too). You're stuck with the landforms we know. OK, if Norway were tropical, it wouldn't have fjords, and Baffin Bay might not exist without the last Ice Age to weigh it down, and so on. Change details, if you can justify them. But hands off world geography!--the tectonic plates, continents, seas, shelves, mountain ranges. Don't shift the continents around, or add new ones. No matter how you turn things, the Pacific is big, Tibet is high, Timbuktu's a long way from the sea. You get to choose only one thing--the placement of the poles. The rest, you have to extrapolate. Because nothing teaches climatology faster than having to create a climate.

Oh--one final question. Do you like the world you made?

EXAMPLE 1: Seapole--a flooded world
EXAMPLE 2: Shiveria--a steady-state ice age
EXAMPLE 3: Turnovia--the world on its head
EXAMPLE 4: Jaredia--a Petri dish for cultural diffusion

Planetocopia, a series of virtual worlds, includes Tilt!, Futures, the Biosphere Variations, and Caprices.
See also dreams of alternate Earths.