World Climate Lab

World Climate Lab runs a climate model on your desktop. Give it a world and watch, over a few minutes, how winds, rain, ice, deserts and ocean currents develop year by year. You can import a map, create terrain, or change a planet’s star, orbit, rotation, atmosphere and moons to see how those conditions shape its climate.

Create a world

You can import maps that define a planet’s height, coastlines, depressions and sea floor. Heightmaps can be greyscale or colour and any size; 16-bit maps preserve gentle slopes, while the planet’s gravity and rock determine how high mountains can rise. A sea mask sets coastlines regardless of height, or you can adjust sea level with a slider. Depression masks can keep basins below sea level dry, where air is denser and warmer, rivers end, and lakes form where water allows. If you do not supply a bathymetry map, the game generates continental shelves, slopes and abyssal plains. Earth includes its real coastlines and sea floor.

The Topography Creator is an in-game terrain editor. You can start with a blank ocean, import a map or generate a world of drifting plates, then sculpt the globe with 73 brushes, stencils and generated landmasses. Reshape the planet with a height curve, erode it and carve river valleys, or trace reference images using guide overlays. Export terrain as 16-bit maps or send it directly to the simulation.

Set the planet’s conditions

You can configure worlds around stars ranging from cool brown dwarfs to hot blue stars, including old white dwarfs and pairs of stars. Each star’s light affects the climate; for example, a red dwarf’s infrared warms snow and ice differently from sunlight. Set the planet’s distance, orbital eccentricity and season of closest approach, and tilt it by up to 180 degrees to make it spin backwards, with the sun rising in the west.

Set any day length, lock a face to the star or use Mercury’s 3:2 spin. The world can be a planet or a moon, with up to three moons of its own to raise tides and warm it from within. Choose an atmosphere containing from trace amounts to 100 bar of nitrogen, carbon dioxide, hydrogen or methane, plus ten trace gases including oxygen and ammonia. An atmosphere profile shows whether a person could breathe there and why not.

Follow climate changes

Changes affect the whole system: slowing a planet’s spin widens its climate bands, while locking it to its star divides it into a warm day side and a frozen night side. You can also change the atmosphere, coastline or star’s brightness and observe the resulting climate. The Energy Flow view traces the planet’s energy and indicates whether it has settled, is still warming or cooling, or is running away.

Read the climate

The game provides 22 ways to view a world. All maps use the same simulation, so rivers follow rainfall, forests follow water and ice follows cold. You can hover over any location for its values, step through the seasons of the orbit, switch between a map and globe, and display temperature, rain and pressure as contours.

• Surface: topography, rivers, lakes and ice cover.
• Satellite: a true-colour space view with clouds, a night side and plants coloured by their star’s light.
• Vegetation: vegetation cover and soil moisture.
• Climate: climate zones, temperature, rain, snow and aridity.
• Atmosphere: pressure, cloud, winds, humidity, dew point, wet-bulb heat and the energy budget.
• Oceans: surface and deep currents, current paths and tides.

Earth-like worlds use Köppen’s 31 climate classes. Slow-turning and tidally locked worlds have their own climate classification systems, designed for places where day and night take the place of seasons. These include twilight cloud forests, frozen night wastes, and seas ranging from permanently icy to boiling.

Export maps and data

You can export plain maps or framed posters with a title and key, at sizes up to 8192 by 4096. Exports can include every layer at once or a full year of seasons. You can also make animations of a year of clouds, winds, currents, temperature or rain, or export climate data for other software, including temperature, rain, snow, soil water and climate classes, yearly or month by month. Cloud maps can be exported as a seamless year at 8192 by 4096 for animation.

Earth and the model

The Earth preset uses real coastlines and sea floor. Whenever the model changes, it is checked against observed climate zones from 1991 to 2020. An illustrated Data Bank explains the controls, climate systems and what the model does and does not simulate. An experimental beta offers a Detailed model with a twelve-layer deep ocean.