Habitability of a planet with highly variable temperatures

Question

The surface of the planet I have envisioned is almost entirely desert save for several city-sized "oases," or pockets of water, flora, and fauna that do not exist elsewhere. The temperature fluctuations on this planet are abnormally high, perhaps resembling that of the Gobi Desert in China (around -20 Fahrenheit to 90+ Fahrenheit in one day-night cycle). This would mean that at night, the desert would freeze over, but by midday, temperatures would be sweltering.

Would humans be able to live on such a planet (as a full-on civilization, not just as nomads)? I expect that humans would settle at these "oases" and begin agriculture there, but with such dramatic climate variations, would that even be feasible?

Assume for this question that this civilization has access to Renaissance-level technology, and that this planet's wildlife resembles that of Earth's.

Addendum: Due to the abundance of questions on the topic, I figure I should probably add some more details about the world as a whole.

• The world is not one single, uniform biome. Although generally speaking the planet is more desert-like than Earth, the poles are, as one would expect, freezing wastelands almost year-round, while the equatorial region is essentially a scorch zone. Any reasonable group of settlers would probably find it easiest to survive right in between the two. Some regions contain more water than others, and while oceans as we know them do not exist, I'll say for the sake of the question that relatively small, saline seas pockmark the planet as well.

• "Earthlike" flora and fauna is relative. Obviously you won't see penguins waddling about the surface of my planet, but creatures and plants similar to those of Earth's harshest deserts, with various adaptations to maintain homeostasis despite the environment, do exist.

Answer 1

First some caveats/issues with the setup, some of which are mentioned in the comments. Your setting has some gaps/logical inconsistency. Though after I mention these caveats I will attempt to give you an answer specific to the point in time you lay out in your question.

• Humans, as we know them likely don't evolve in this environment, humanoids of some sort may evolve, but they'd be a whole lot different.

  • They'd likely be thicker this is good insulation and helps with water retention
  • With their extra girth they'd also have tougher skin, similar to some lizards perhaps who have skin that collects water.
  • They'd also probably be active twice a day during the dusk/dawn hours to minimize exposure to extreme temperatures

• Single biome planets don't really make sense. The variation in lat/lon any axial tilt etc, virtually guarantees that some variation will exist in your biomes. This is pretty easy though, just refrain from introducing other settings, put some big huge mountains in the way or something so that the people in the story don't realize other biomes exist.

• It's going to be tough to get significant plant life let alone animal life to thrive in this environment. You are simply not going to have Earth-like creatures on a world that has totally different selection pressures than Earth. Creatures and plants that do show up will have to be different. Plants would end up as some cactus/pine tree hybrid and in reality it would probably just be scrubby and dormant most of the time. Animals would be tiny and would likely burrow to avoid the temperature fluctuations/retain water. You could in theory have wholly underground cave based biomes where temperature is moderated and water readily available.

• You're going to need seasons...at least a relatively wet season to give plants a chance to grow and whatnot, this would also moderate the temperature swings (humidity is good at that) over night. So the whole year shouldn't be the same temperature wise, this goes back to the single biome conversation, worlds are big and climate is complicated. A static climate breaks suspension of disbelief for me.

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Ok, on to your question. How do we make this settlement work (ignoring how we got to this point in the first place):

• Humans can certainly survive in this place. A reasonable/likely setup comes to mind.

  • Clearly civilization will cluster around your oases. It provides water and at least some temperature normalization during the hot days/cold nights.
  • For dwellings your best bet would be to have underground lodgings, again this helps manage the temps. Alternatively you could create stone structures that will bake in the daytime heat and then radiate that heat throughout the cold nights. I would expect to see a lot of covered streets and shaded lanes for daytime...like with camouflage netting.
  • You could hypothetically harness the daytime heat to create simple steam powered generators or tools. A mill for example.
  • Windstorms....you're probably going to have crazy strong winds on this planet. This will impact where and how you build. Dust storms would be...messy. Buildings are going to be low and sturdy, thatch/mud huts are just not going to cut it...

• Agriculture. You can't have a civilization without ag, at least not in the "lets build a permanent settlement" sense.

  • Water. Water seems easy enough based on your setup. Space is going to be geographically limited any decent distance from your oases and the soil will be too barren to support life. Hypothetically you could gradually expand your ag space over time by keeping land wet so microbes and little critters could survive further and further from the water sources. You're going to need canals and whatnot.
  • Soil. As mentioned the soil will be sterile any reasonable distance from town...so collect all your poop, you're going to need it to fertilize.
  • Temperature. Clearly sunlight is not a problem...actually you have so much it becomes a problem. You're going to want to tent your fields with fabric to keep everything from roasting during the day. A low tech solution comes to mind for the night though. Surround and criss-cross your fields with stone walls. Like your dwellings they will absorb heat during the day and then radiate it through the evening, that should keep the air temp from getting too cold for your plants at night. In the end it probably just makes sense to have plants that have evolved to this place so you don't have to deal with this.
  • Wind. As mentioned wind is going to be strong on this planet, so you are going to need walls/berms/some form of wind break to keep the winds from ripping your plants apart.

A general note. Unless these oases are fairly common and fairly close to one another, as in, a bird could make the flight in a few hours you are going to have problems with genetic diversity. Pollination and such could be a problem and depending on the population size of your humanoids you could have issues as well.

Answer 2

So i read all the other answers and, while truthful, they do not satisfy my mind.

The main problem of survival would be the freezing as, as far as we know, every lifeform is based on water. BUT: there are several species which are able to survive body-temperatures lower than 0°C. While water itself would freeze at those temperatures, mixed with specific ingredients (like some kind of salt or alcohol) the freezing point could drop way lower. So it would be possible that in this harsh enviroment a kind of plant could have developed which creates such substances to be able to function in these temperatures. Same goes for animals.
Those substances may even be the key for the survival of humanity. How they'll use it is up to the author. Here are some of my ideas:

• through consuming those substances, humans are able to survive lower and higher body temperatures, making them more durable
• those substances may be collected and used to melt ice on demand
• those substances may be able to conserve food longer
• etc...

Answer 3

(around -20 Fahrenheit to 90+ Fahrenheit in one day-night cycle)

It's something around -30°C to +30°C. That's a place where a human with a "Renaissance-level technologies" known as "fire" and "clothes" can survive.

However I can't imagine how one can get enough fuel to keep himself warm at night, since you're mentioning "desert-like planet".

and begin agriculture there

This doesn't look possible, since simple models of greenhouses can't save fruitful plants from both freezing at night and drying out at the daytime. It's quite possible nowadays with electricity and automatised climate/humidity-control systems, however these don't fit into "Renaissance-level technology".

So, the short answer is: No, you will need to think of some explanation of how is it possible.

Possibilities to take into account:

• to introduce some "magic" to replace technology (i.e. "magical domes" or "places of power" or "ancient artifacts", that keep weather near your oasis somewhat stable)
• to reinvent the evolution of your world (i.e. "plants and humans are totally thermal resistant because ..." , OR the sand can be used as fuel or smth even more complicated).

Answer 4

We have lived in harsher temperatures on Earth, but that's not your biggest problem

Communities in most desert / arid environments on Earth have to deal with a high diurnal range (midnight to midday contrast) of temperatures, often with less technology than evident in the Renaissance.

By using high thermal mass materials, ie. heavy thick walls and roofs, with the option of active systems such as shade structures, stack ventilation or cross ventilation, ice harvesting or wind towers - it would be possible to adapt to these environments. Thermal mass 'delays' temperature transfer from outside a building to inside, depending on your wall thickness. You can use this to even out the temperature throughout the night/day cycle, accompanied with the above active techniques.

However, being a foreign planet, your biggest problem is that our immune systems and bodies are not setup to compete with alien bacteria, viruses or molecules even if the atmospheric composition is the same as Earth. Even deserts are super-saturated with microscopic living organisms on Earth, if life evolved independently on your planet this would be your primary issue, you would not be able to take a breath outside without dying (or even expose your skin).