Worldbuilding with real worlds
Lieutenant Elena Jones shivered with excitement as her Ecological Survey craft entered the atmosphere. She checked the readings in front of her carefully. This was her first solo mission, and she was determined to do everything just right. She came in over the major planetary ocean, following the prevailing winds. She stared out the window at the coast, her first sight of land not filtered by cameras and instruments. Her planet, hers! Not just her first sight of this Earthlike world, but the first sight ever. Elena guided the little survey shuttle over the high coastal mountain range, and leveled the craft out over the lush green tropical forest beyond.
Hold on, something’s wrong. Did you spot it? (Besides the cliches; we’re here for the science.) The worldbuilding here jams the components of a planet together randomly instead of fitting each piece into its proper ecological spot. A tropical forest doesn’t go downwind of the coastal mountains on an Earthlike planet. Major categories of vegetation and their associated animal life, called biomes, can only be found in particular places. At a global scale, the locations of desert, grassland, forest and tundra biomes are determined by temperature and precipitation. At a particular site other factors like soils and disturbance come into play, but let’s stick to whole planets for now.
If you draw a graph with temperature as one axis and precipitation as the other, each kind of biome can be added as a region.
Tundra is very cold and dry. Deserts are dry and can be warm or cold. Grasslands are dryish and warmish. Tropical rainforests are warm and wet. That’s pretty straightforward, but how are the different types distributed on a planet? Deserts and grasslands and rainforests all belong somewhere, but why?
We only have one sample to extrapolate from, but at the planetary scale it’s all physics, and the physical principles that determine biome placement are general to Earthlike worlds. Like so many other things, it’s all about energy. Our planet’s major source of energy is the sun, so insolation (the amount of solar radiation received) is the driving force in global climate.
If the sun is directly overhead, a sunbeam will be concentrated in the smallest area and providing the greatest amount of energy per square meter. If the sun is hitting at an angle, the same sunbeam hits a larger area of ground and the energy is more diffuse.
The angle at which the sun’s rays hit the planet varies with latitude. That’s why it is warmer at the equator than near the poles: more energy received. Seasonal patterns come from both latitudinal differences and the angle of the Earth’s axis: during the summer, the polar regions are receiving more direct sunlight, and so greater energy density.
The timing is reversed for the southern hemisphere, but the shape of the curves is the same: more energy overall near the equator, more energy in the summer and less in the winter at higher latitudes.
The geographic pattern of annual insolation looks just like that at the top of the atmosphere: highest in the tropics, moderate in the temperate zone, and lowest at the poles.
The surface of the planet is part land and part water so it doesn’t heat evenly, but the tropics are warmer than the poles.
So that takes care of temperature, but solar radiation is also responsible for the global atmospheric circulation – the prevailing patterns of winds.
Warm air rises and cold air sinks. At the equator, the land warms the most and heats the air above it. The warm air rises, and air from farther away flows in to fill that space. The warm air rises, moves away from the equator and cools, sinking again. There are three of these circulation cells in the northern hemisphere, and the same in the southern hemisphere. The direction of planetary rotation figures into it too (ours turns west to east).
The same patterns of heating and air movements control the dominant precipitation patterns. Warm air can hold more moisture than cold air, so when warm air rises and cools it has to drop its moisture.
That creates a rain shadow, and explains why deserts are downwind of mountains. The combination of temperature and precipitation explains why all the biomes are where they are.
And that’s all there is to it: the sun powers everything, driving temperature and global circulation patterns, which interact with topography to determine precipitation patterns. The physical principles are broadly applicable, and can be used to predict biomes of the late Jurassic, or of your latest fictional world.
Start with the location of the continents. Where are the mountains? Which way do the prevailing winds go? What parts are hot? Dry? Cold? The World Climate Charts site has excellent maps of all sorts of climate parameters that will help you get a feel for how everything goes together in a science-based world. Build a realistic geography, then use it to fuel your story.
But there’s no reason your planet has to be physically like ours: farther from the sun, or nearer; with a different axial tilt, or none, or just an entirely different continental layout. Any of those factors can shift the planetary proportions around on that first temperature-precipitation graph. Most of the planet could be hot and wet, or cold and dry, or whatever suits your story. Just make sure there’s science behind it, as well as imagination. (And I didn’t talk about it at all, but don’t forget that it gets colder as you go up in elevation too.)
Once the deserts and forests and grasslands are in the proper places, then comes the fun of figuring out what lives there: plants and animals or something entirely different, things adapted for hot or cold, wet or dry. Do these organisms need to conserve heat or get rid of it? Find water to drink or avoid it?
How much would an alien desert look like ours? Or a forest?
Climate affects so much of human or alien culture as well. What kind of shelter is necessary? Is water available (if needed)? The biome may determine what kind of food, building materials and other natural resources are available, and also the predators, pests, annoyances. If you follow these basic principles you’ll know that your planet is plausible.
Elena guided the little survey shuttle over the high coastal mountain range, and leveled the craft out, flying low and slow over the broad open grassland beyond. Look, elephants! If elephants had trifurcated trunks and irridescent spines, anyway.
I’d like to do more Worldbuilding posts, if there’s interest. Lots of information from ecology can be extrapolated into designing new worlds, new ecosystems, new organisms. Some possibilities: plate tectonics, continents and mountains; soils and agriculture; terraforming; oh, lots of things. And then there’s the non-worlds: closed ecologies.
Would you, Faithful Reader, be interested in more Worldbuilding and ecology?
I would most definitely be interested in more world building posts, so please, keep them coming!
I’d love to see some. Definitely one or two lightbulb-over-head moments here.
Hooray! Thanks for letting me know.
I’d definitely be interested inmore worldbuilding ecology—more, I’ll admit, for the ecology than the world-building at this point, but maybe you’ll spark something. Great post!
Single environment planets (not necessarily human inhabitable ones) would be more realistic than tropical forests downwind of mountain ranges. Though most people think the opposite for some reason.
True, though I can think of more fictional examples of single-type planets than I can of really good multi-biome planets not mimicking ours. Desert planets, water planets, jungle planets… I think those are easier fictionally.
Great post, thank you.
I have a tendency when trying to world-build along these lines (for a game or for one of the little writing things I’ve put back on the backburner again) is to cheat: I don’t know if ProFantasy’s Fractal Terrains software has a good climate-building engine, but I’ve let it do the work for me nonetheless. Even so, it’s nice to have an accessible explanation of how these things ought to work–so, yes, ‘t’would be interested in reading your further thoughts on the topic.
As for single-biome worlds in fantasy and SF: not only are they easier fictionally, but in space opera what you frequently have is the word “planet” being used to replace what might otherwise be words like “region” or “territory” in a swords’n'sorcery story, fairytale or other kind of fantasy. It’s not just easiness, but a consequence of everything being bigger in those kinds of stories; e.g. the “…in a galaxy far, far away” in Star Wars that replaces the fairytale “land far away” formulation.
Makiyivka, Eric, thanks for the encouragement. I will definitely do more worldbuilding.
Eric, I don’t know how Fractal Terrains does it, but it wouldn’t be too hard to have a decent engine at the scale that I talk about it this article. It gets much harder very quickly from there – entire scientific careers are spent modeling climate. And that’s a good point about the single-biome worlds.
Can any of you think of well-laid out fictional planets? Or bad ones?
As far as I can tell as a non-ecologist, the planets in Bujold’s Vorkosigan novels are designed well, with a range of Earth-like to tropical to desert. She also seems to have a good handle on terraforming.
It’s been a while since I read any Pern novels, but I can’t remember any deserts (and few grasslands), despite all the mountains.
I love good worldbuilding, have done it myself, and would definitely enjoy more on the subject. Most SF planets are barely thought out, and usually have only enough context to advance the plot (it’s also hard to give names to flora and fauna that aren’t tone-deaf).
Contact has the Epona project and Calvin sent a very interesting link to a site earlier on, that shows extrapolated flora and fauna on earth at different future points. My worst disappointment in this domain was Medea, an ambitious anthology helmed by Harlan Ellison. It started promisingly, but quickly degenerated into pretentious dullness. I finally flung it across the room when they postulated that the major lifeform starts female and “totally instinct-driven” and later ascends into… you can guess the rest.
Mesklin in Hal Clement’s Mission of Gravity is often brought up as one of the best “hard SF” worldbuilding experiments, though he stints on the social/cultural side. For my part, one of my favorites that bring the world to vivid life across domains without any infodumps or false notes is Joan Vinge’s Eyes of Amber (Titan with indigenous sophonts). Two others, that show human adaptation to extremes, are Ursula Le Guin’s ice-bound Gethen in The Left Hand of Darkness and Donald Kingsbury’s harsh semi-poisonous Geta in Courtship Rite. A quirky one that straddles SF and F is the tidally locked world in Roger Zelazny’s Jack of Shadows.
Plant names… heh. No self-respecting SFF author could get away with the names that are really used: soapwort, birthwort, St John’s wort… Wikipedia even has a list of Wort plants. “Wort” just means plant in Anglo-Saxon English. Although I suppose an author could do worse than to take a bunch of obsolete plant names as a starting point…
But really, the names (common; scientific are a different issue) are a product of the way people interact with plants and animals. How they look, smell, taste, feel; their flowers, leaves, trunks. Shagbark hickory, striped maple, cutgrass, lambsear, sheep sorrel (means sour, back to Anglo-Saxon, and lives in pastures), skunk cabbage. Names for the sake of names are useless (look at some of the common names invented recently for the sake of having a unique common name), but meaningful names can be very evocative. And sometimes wrong: spikerush is a sedge and not a rush; broomsedge is a grass and not a sedge; and so on.
It would be reasonable for colonists on a strange planet to name things for old familiar cognates. We’re all familiar with the idea of “New New London”, but what about calling a common yellow-flowered herb dandelion? Or liontooth? Or false dandelion?
I’m a botanist, well-experienced in plant taxonomy and with an interest in plant names, in case it wasn’t obvious. And Friday afternoon is leading me astray!
“It would be reasonable for colonists on a strange planet to name things for old familiar cognates.”
Definitely so, if the colonists are human. Not otherwise. However, naming them an evocative composite will do very well. In my story Planetfall, the human explorers call a sapient aquatic species mershadows. But their name for themselves is neghír/neghirán.
“It would be reasonable for colonists on a strange planet to name things for old familiar cognates.”
Definitely so, if the colonists are human. Not otherwise.
Sure it is. But their old familiar cognates wouldn’t necessarily be ours. For instance, keep the pattern of “wort” plants, but with a different word. Or have a “false somethingoranother” rather than false dandelion.
There are other ways to do it, but I don’t think that’s at all unreasonable even though it makes more work for the author (need to be familiar with the homeworld’s ecology as well as the new world’s).
I think I didn’t express what I wanted to say clearly. I agree with you that if you are narrating from the alien viewpoint, the names for flora/fauna native to the planet can easily and well be earth cognates, slightly tweaked for uncanniness. But if the POV switches back and forth between human and alien, the alien word when heard by the human cannot be “false dandelion”.
This is great! Yes, more more!
I do have one quibble though –
Having traveled a little in tundra areas of northwest & southwest Alaska: very wet in the summertime — bogs, marshes, ponds, lakes, streams. Thanks to the permafrost, there’s no way for surface water to percolate down, so it just kinda sits above the permafrost making everything quite soggy. Here’s an example centered on Bethel, Alaska, an area I made several trips to in the ’90s.
Mel, thanks for the comment, and you bring up a good point. Biome classifications are based on overall characteristics. Tundra is dry because it doesn’t get much precipitation. Bethel, Alaska gets 15 inches of precipitation a year, putting in in the semi-arid category. Worse, what water there is is frozen for most of the year, and so not available to plants. You were lucky enough to be there during the brief wet season, when the top layers melt enough to provide plentiful water. Tundra’s not like that for most of the year.
National Geographic has a more detailed discussion.
I’m jealous – I haven’t visited the tundra yet.
Really interesting!
It got me thinking about my own local biome (semi-arid desert). In much of the area the indigenous vegetation has been replaced by non-native trees, grass, and other plants that are considered either more decorative (lawn grass and flowers) or more useful (orchards) than the originals.
How likely would it be that intelligent life on other planets would do the same? Could we use “out of place”vegetation on another planet as a sign of intelligence?
Unless heroic precautions are taken (and probably even then), we’ll be exporting our species everywhere we go. Some will go intentionally – things we need to eat, or produce oxygen, or perform other services, and others will be along for the ride. Seed contaminants, stow-aways, people smuggling pets.
We’ve already made a mish-mash of our own ecosystems, both in the landscaping context that you mention and other less-noticeable ways.
But that isn’t really what you asked. In a case like yours, with species brought into a desert, those species must be irrigated and tended to survive. Is that a sign of intelligence? (Or stupidity?) What about the ants that tend gardens of various kinds? I wouldn’t say they are intelligent, but they keep other organisms alive.
It could go all sorts of ways. Find a green patch in the desert:
1. Landscaping by sentients.
2. Landscaping my non-sentients.
3. Remnant of previous occupation, like finding a big patch of daffodils out in the woods.
4. Something quirky in the local ecology.
Interesting post.
Two points if I may…
Regarding the biome graph (your first figure) I have found the Holdgate three-way matrix of temperature, precipitation and potential evapotranspiration a more useful way of charting biomes. (Alas I have had quick trawl of the web and can’t find it, which is a shame as this is not new an dates from at least the 1990s…)
The advantage of adding potential evapotranspiration is that there are places where the potential exceeds precipitation which leads to a different type of desert and relationship with other biomes compared to that on the two dimensional (temperature and precipitation) portrayal.
Regarding “How much would an alien desert look like ours? Or a forest?”
I give an exobiology talk which is in no small part using exobiology to sugar-coat some ‘real’ (forgive the term) biology. In it I note the tension between divergent and convergent evolution and also (given the shape, form and function principle) the difference between homologous and analagous forms.
Consequently, taking both these together, it is quite likely that on Earth-like planets that at a distance desserts and forests would look the same but get up close and leaves (for example) would have a different histological structure.
Hope this makes sense.