Question about climate and geography

Question

I have been asking around a bit because i am trying to create a world for a story i'm writing. And after some loose questions i think the better way to get an answer will be to just list the criteria i try to get into this world and let the better educated among you provide me with some answers.

What i need is basically a world that has earth like climate but without deserts (or as little desert area as possible) and without tropical rainforests. (Tundra and taiga like regions are ok) (as are icy poles if there is no way around it) I'd also like to keep the amount of continents as low as possible. (preferably one supertonitent like Pangea, two continents connected by a narrow land bridge or two continents seperated by an ocean. All suggestions are welcome.

CLARIFICATION: Some of you seem to think i am asking you to do all the work for me in designing the world i want. That is not my intention, All i want is suggestions in where to place things like continents and oceans to achieve a world as close to my above description as possible.

Answer 1

Some causes of desert areas could be offset with some unique geography characteristics and geothermal activity. Two types that could be easily defended against are Rain Shadow deserts and Midlatitude deserts.

Rain Shadow deserts border large mountain ranges which affect the air moisture of the shielded area:

Rain shadow deserts are formed because tall mountain ranges prevent moisture-rich clouds from reaching areas on the lee, or protected side, of the range. As air rises over the mountain, water is precipitated and the air loses its moisture content. A desert is formed in the leeside "shadow" of the range.

Midlatitude deserts like found across the continent of Africa seem harder to resolve, but perhaps large-scale geothermal activity could combat the pressure systems that create this type of climate. Another option would be to have limited land forms in this latitudinal range.

Midlatitude deserts occur between 30° and 50° N. and S., poleward of the subtropical highpressure zones. These deserts are in interior drainage basins far from oceans and have a wide range of annual temperatures. The Sonoran Desert of southwestern North America is a typical midlatitude desert.

This simple analysis came from my reading of this USGS site. Could be helpful for you.

Answer 2

• Earth like climate:

  All right, it has an Earth-like climate.

  But what does this mean? The climate of Earth varied quite a bit during it's history, from the all-frozen frigid snowball Earth in the Cryogenian period, some 650 million years ago, to the balmy and lush Carboniferous period, around 330 million years ago.

  The Carboniferous was a time of active mountain-building, as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe (Laurussia) along the present line of eastern North America. This continental collision resulted in the Hercynian orogeny in Europe, and the Alleghenian orogeny in North America; it also extended the newly uplifted Appalachians southwestward as the Ouachita Mountains.

  Average global temperatures in the Early Carboniferous Period were high: approximately 20 °C (68 °F). [...] Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. (Wikipedia)

• But without deserts (or as little desert area as possible):

  Make your continents small-ish, and tweak them to be elongated in the direction of the prevailing winds, with no transversal mountain ranges to create rain shadows. On the present-day Earth, Europe is a good example; there are no high mountains barring the winds from carrying rain from the ocean, with the effect that there are no true deserts in Europe; the worst we have is steppe, and rain-based agriculture is perfectly possible in the Russian steppe.

  Note that present-day Europe is about the maximum size of a continent without deserts; deserts begin just east of Europe.

• And without tropical rainforests. (Tundra and taiga like regions are ok):

  If you don't want tropical rainforests then don't have land around the Equator. The nature of atmospheric circulation is that around the Equator there is little wind, which, combined with high evaporation due to the heat, makes the condition for daily rainfall.

• (As are icy poles if there is no way around it):

  Most of the geologic time Earth does not have icy poles. We currently have ice caps because we live in an ice age, albeit in an interglacial. The southern ice cap is big and thick because we have the Antarctic continent there, surrounded by open ocean which creates a permanent ring of winds which insulate it from the rest of the ocean and atmosphere. So...

  • Make your world slightly warmer than Earth. This is perfectly reasonable, as Earth is unusually cool, geologically speaking.

  • Don't have continents at the poles.

  • Don't allow unbroken spans of ocean around the poles.

  Look at the difference between the north and south poles of Earth.

• I'd also like to keep the amount of continents as low as possible. (preferably one super[contin]ent like Pangea, two continents connected by a narrow land bridge or two continents seperated by an ocean.):

  All right, make it so. Remember that you want your continents small-is, elongated east-west, with no big transversal mountain ranges, and no land near the equator or near the poles. Deeply indented coasts (consider, for example, how the Baltic extends deep into Europe) help.

Further notes:

• Tectonic plates don't have to carry continents (e.g., on Earth, the Pacific plate), and even if they carry continents they don't have to be above water (e.g., on Earth, Zealandia). This may explain why the mountains are the way you need them to be.

• Don't overdo it. Better to have two Europe-sized continents in the northern hemisphere, separated by a relatively narrow sea (say, one third or one quarter of the Atlantic ocean) with ocean all around them, and leave the southern hemisphere for further developments. Maybe later you will want to have some colonial expansion.

Answer 3

Ok, there are a few mechanisms that could allow your planet to have continents with reasonably uniform climate.

Thicker Atmosphere

The thicker the atmosphere of your world, the more heat will be distributed between the equator and the poles. There will still be temperature differences, but they will be less severe than on Earth.

Doubling atmospheric pressure at sea-level will help a lot, but will not be so severe that it has untenable consequences that render the planet non-Earthlike.

Consequences: A thicker atmosphere means stronger winds. Hurricanes will be much worse.

Bigger Planet

By this I mean a planet with a greater surface area. If the world is bigger, there will be more area within a given climate band. You can offset any unwanted increase in surface gravity by lowering the density of the planet.

Consequences: Larger planets have greater mass, and therefore higher surface gravity. If the mass of the planet is greater than about 2.5 Earth masses, it is predicted that a transition zone will form at the bottom of the mantle that severely restricts heat transfer from the core. This means stagnant tectonics, and a dead planet.

Also, if you lower the density of the planet too far, that implies that the metallic core will be smaller. This results in a weaker magnetic field.

Smaller Continents

Smaller landmasses mean that no given point on the continent is as far from the ocean, so you are less likely to get deserts in their interiors. Supercontinents are a bad option because they will inevitably be surrounded by subduction zones, which produce mountain ranges, which worsen the interior aridity by producing a rain shadow.

Continents Restricted to Equatorial or Temperate Region

If your continents are strung out along a narrow band of latitude, they will have the potential to share similar climate. If you use the aforementioned "Bigger Planet" idea, this latitudinal band can be wider, and with a thicker atmosphere this band will be wider again.