Let there be absolutely none, exactly 0 axial tilt. Let the earth's orbit around the sun be a perfect circle with 0 eccentricity and a surface to surface ( constant) radius equal to the harmonic mean of the surface to surface earth to sun distance through the past 800 years(an integral if time is thought to be continuous or measuring the distance every quantum, least increment of time, for 800 years). Let the sun be a perfect sphere and the earth be a perfect sphere(no mountains, cliffs, valeys, deeps) too. Let the angular speeds of earths movements(Revolution, Orbit, etc) be ever constant(a day of 24 hours and a Year of 360 days). Let the consistancy of the Earth to the core be perfectly uniform with a perfectly uniform surface(allowing the exception for an amount of rivers running through perfectly straight lines of longitudes with a symmetric distribution between the latitudes so the human civilisation could have water and thrive). Let the consistancy of the rivers/ocean and atmosphere be perfectly uniform with a breathable partial pressure and a tolerable total pressure.

I tried to make the climate as uniform as possible and not simply remove Milankovitch Cycles. I do not have any ideas how the climate could be more uniform if anyone has any ideas I would be happy to think about them.

Now to my question

How will Earth's climate be and how will that climate affect human life and civilisation?

I think that the poles will shrink as there would not be any winter, the variance would be minimal and largely due to longitude difference rather than to latitude differences (proximity to the rivers could play a minor roles), the average temperature would increase, as less heat will be radiated back to outer space and more of it kept on earth (Radiation of Black Body). I want my hypotheses confirmed and a way to imagine how the climate would be. As for the consequences to life and civilisation I have no ideas.

N.B I tried to ask a similar question on Earth.Sciences because I thought it belonged to climatology and planetary science but they refered me to worldbuilding.

  • $\begingroup$ Life never evolves because you've stripped too many irregularities which help its evolution. You've neglected a moon, which is a major factor, and the entire planet has one biome, which sounds like a good thing, but completely isn't because of the lack of diversity, which, for instance, means a single disease on a crop wipes out everyone, as only one kind of crop would develop. $\endgroup$ – Halfthawed Oct 24 '19 at 13:04
  • $\begingroup$ Look at Jupiter: You get an atmosphere with a distinct band structure, very strong and longlived storm systems, and plenty of ordinary turbulence. And the band structure means: Distinct climate zones, and pretty cold poles. $\endgroup$ – Karl Oct 24 '19 at 19:56
  • $\begingroup$ @Karl I do not know what band stucture precisely means. Does it mean that there are layers with uniform consistency within them but between one another the consistency is not uniform? I meant a whole atmosphere that has a single uniform consistency between all latitudes, all longitudes and all altitudes up to the Thermosphere. Each and every small ml of Atmospheric air should have the exact same consistency. $\endgroup$ – George Ntoulos Oct 24 '19 at 20:20
  • $\begingroup$ @Karl I required an uniform atmosphere so more than a single band would not be compatible. $\endgroup$ – George Ntoulos Oct 24 '19 at 20:22
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    $\begingroup$ And just to note everything would die if it ever evolved at all. Nothing will propagate and all water will pool at the equator, then stagnate. $\endgroup$ – Vogon Poet Oct 26 '19 at 2:23

No moon to stabilize the planetary axis of rotation .. AND "pull on the hand brake" .. so the day length would come close to 6 to 8 hours - which in turn propels wind speeds to some hundred km / h on "not so windy" days and easily over 1000 km/h on stormy days ...

IF any life would form - it would be very flat.

The lack of the moon has another "after effect" - thesis never collided with your version of earth, meaning the cores of both proto-planets wouldn't unite. Your theoretical earth would be solid in a few hundred million years after it formed. - Now for a small experiment try rolling around a cooked egg vs a fresh egg. Your earth would spin even faster after the core and mantle solidify. All this would lead to a terrible weather. Your earth would lack tectonics bring enough green house gas into the athmosphere = once the core and mantle solidify your earth would turn into a iceball, provided your version of the solar system allowed your earth to collect enough comets and asteroids to deliver the water. Once cold, there is nothing that can help your planet.

You have a deeply frozen planet, with heavy storms about all the time, instable rotational axis - which would "skip" around at random time spans (our axis slowly rotates over ~ 26000 yrs stabilized by the moon) - the athmosphere of your planet was never "cleaned" of Ammonia and methane and other more toxic gas.... The constant skipping of the planetary axis would make it impossible for any climate zones to form - in principle you have pure (COLD) chaos as climate

  • $\begingroup$ Is a carefully placed moon incompatible with the lack milankovitch cycles? Are we in a dillemma between milankovitch planets or moon? $\endgroup$ – George Ntoulos Oct 24 '19 at 15:24
  • $\begingroup$ I did not understand "The lack of the moon has another "after effect" - thesis never collided with your version of earth, meaning the cores of both proto-planets wouldn't unite." Particularly "after effect" - thesis never collided. Who didn't collide with my version of earth? Thesis is the subject of the verb to collide with?Your earth would lack tectonics bring enough green house gas? Did you forget a to between tectonics and bring. I am more comfortable with an to + infinitive. $\endgroup$ – George Ntoulos Oct 24 '19 at 15:29
  • $\begingroup$ Is a clean atmosphere incompatible with a perfectly uniform one? $\endgroup$ – George Ntoulos Oct 24 '19 at 15:30
  • $\begingroup$ As for lack maybe substitute adbsence if anything for idiomaticity. As someone who speaks English as a Foreign Language I am quite punctilious and verbose and less idiomatic. $\endgroup$ – George Ntoulos Oct 24 '19 at 16:38

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