Let's assume that the earth has stopped spinning. To be clear, the earth did not end up being tidal locked with the sun, but instead, it would just stop rotating around its own axis. This should result in, for instance, one side being exposed to the sun for 6 months, then covered in darkness for another 6. The scientific reasons behind why that happened are not relevant, but in this scenario, within 20 years the world comes to a complete stand-still. What I'm curious to know is:

  • What would be the immediate impact (and by immediate I mean within that 20 year time frame) on the weather and the landscape? I can imagine that there would be earthquakes, as well as storms due to the change in atmospheric pressure due to one side of the earth being cool for longer vs. the other being exposed to more heat. There's also the element of the ice caps melting, which would result on the rise of the sea level. But other than that, what other changes would occur?

  • How drastic would the impact of the earth not moving be on the vegetation within 20 years? Clearly, plants would start to wither and die because the process of photosynthesis would be impaired by prolonged lack of light, yet would there be certain land species (perhaps large trees?) which might survive? If so, which ones?

  • What would be the highest and the lowest temperature point that the earth would have at the peak of summer (when you would have uninterrupted daylight) vs. winter?

To narrow down the list of answers, let's limit the area of interest to the northern hemisphere, namely Europe.

  • $\begingroup$ When you say "the world comes to a stand-still", do you mean that Earth's rotational sidereal motion stops (basically, the Earth becomes tidally locked with the Sun, like how today Mercury is tidally locked with the Sun or the Moon is tidally locked with Earth), or that its orbital sidereal motion stops? It sounds like the former, but it's better to be explicit. If it really is the latter, then the answer is: we fall towards the Sun, and then everybody dies, with the specifics depending on how long it takes for Earth to stop in its orbit and where the other planets are at the time. $\endgroup$
    – user
    Mar 17, 2016 at 22:54
  • $\begingroup$ Where is Europe? Is it in the sun? In the dark? $\endgroup$ Mar 17, 2016 at 23:15
  • $\begingroup$ Edited the question so it's a bit more specific. No, the earth would not be tidal locked, just stop rotating around its axis. And to answer the other comment, this would mean that for 6 months Europe is in the sun, then in the dark for another 6, and so on. I find the prospect of earth falling towards the sun to be a bit extreme, especially within the first 20 years of this happening, but hey, I might be wrong. After all, I'm asking this question because I need answers. $\endgroup$
    – Feidhelm
    Mar 17, 2016 at 23:22
  • 3
    $\begingroup$ there is a documentary about this on YouTube youtube.com/watch?v=nH3bmG-KjvU $\endgroup$ Mar 18, 2016 at 0:10
  • $\begingroup$ Seen it some time ago, but it dwells too much on how human lives would be impacted by all this and, to be honest, I didn't find it very relevant. Cheers for reminding me about it though. $\endgroup$
    – Feidhelm
    Mar 18, 2016 at 0:36

3 Answers 3


Ok so the question you are asking is not that simple of one. Lets look at it by examining the contributions to the world by its rotation.

Diurnial Cycle: Day and night are the obvious effects but lets get to examine it more closely.

First there is heat: as roughly 893.0 w/m2 or 283.6 Btu/f2/hr {using the Solar constant model and the reflection absorption statistics of atmospheric layers provided by http://mb-soft.com/public2/energyso.html} gets to earth with the current rotation, and that Significant heat exchange takes place during the nocturnal time frame enough for a temperature variance of around 21 degrees F or 12 degrees C yearly average. In essence as the day gets longer and the night shorter it becomes warmer as less energy is able to be radiated by night time (there are a lot of other factors but it essentially revolves around two facets of thermal dynamics equilibrium and surface transfer. The earth will always attempt to equal the ambient temperature of the cosmos.

So what happens as we slow down well during the day we get more energy, however at night we lose more. As we lose faster than we gain (in absence of other factors such as clouds, geothermal radiation, and the like) the time in the sun would at first cause your area to become hot. The shortest day where I live average 10 hrs 16 mins in which our high temperature averages 62 Degrees F versus the longest days, 14 hrs 2min where it averages 97 Degrees Fahrenheit. This means that with a difference of 3 hrs 46 minutes of solar activity we encounter a temperature variance of 35 degrees F that 1 degree per ten minutes (rounded out not precise).

Depending on the rate of rotational slowing I think you gave it 20 years... Current rotational rate is 1,674.4 km/h with a 20 year slow that means our rate of slowing is 83.72km/h/year or 229m/h/day... At your rate the first day of slowing would go from 24 hours to 27 hours a relative 3 hour difference assuming that this even diurnal our temperature difference just from that are 35 Degrees. Essentially where I live our coldest day now sees an average of 31 degrees instead of 65. and our Hottest average would jump to 132 Degrees F. in one day most of your plants would die off from exposure to extreme heat or extreme cold.

Evaporation & humidity: The longer cycles means heavier evaporation in the long day seasons and less in the long night seasons. Yes polar caps would melt... in the hot parts, in the cold months there would be an increase in ice mass this means that the tidal patterns would reflect this changing the convection currents to adjust for cold and hot spots.... There is a lot more to this Coriolis effect, Electromagnetic field, Tectonic shifting, and even the geothermic radiation. Leave it to say this.

First day: Plant life dies of shock due to extreme temperature changes. Oxygen production nearly Ceases. The few remaining plant life and oxygen producing algae are limited at the adjust to the temperature swings.

First Month: Famine strikes world populations, Animal attacks against humans increase. As a lack of food drives them to be more daring. The extreme heat and cold causes a temperature imbalance affecting Hurricanes and torrential storms occurring around dusk and dawn most notably.

First Year: Winds begin reach extreme Average speeds, protection must now be worn when outside (Think sand blaster). Most animals are gone, all life has either moved into constructed shelter or natural caves sucking up the little remaining geothermal heat produced by the slowing core.

First Five years: as the electromagnetic field protecting earth from harmful radiation fails with the slowing rotation, Going outside is now a death wish both day and night (though you could survive a bit longer at night). Earthquakes have all but ceased, as the energy needed to drive the tectonic activity has also ebbed with the rotation speed. Temperatures become so extreme that little is left on the surface as any thing with a low flame point is burnt and a low melt point liquefies and is absorbed by the earth. If its still alive it has to be magic...

Please note that we would not fall off the earth as gravity does not work that way. we would however probably be better of if it did.


Someone posted a link to the TV show in a comment already. That pretty much answers the question in all ways, though the time scale was faster.

Other answers here have not pointed out a major effect: the loss of centrifugal force will leave the equator 20 km above sea level. Not only will that reshape the oceans, flooding other areas, but the air will be rather thin. Note that this is twice as high as the deepest ocean trench, so the oceans will drain completely near the equator.

It will take millions of years for the Earth's shape to relax into a sphere, after this instantaneous change in the forces involved.

So a direct answer to the posted question: desert around the middle, extremely high altitude and arid on the day side and cold on the other; ocean without land everywhere else. I've not done any calculations but I would suppose there to be a margin of a few hundred miles at the "shore" where normal weather including rain occurs, before the altitude climbs too high.

But the static weather pattern will probably cause the air to move toward the cold side and rain just in the dark area. Very little geography will route flowing water east-west to the day side, as the enormous and everpresent slope from the equator to the pole will dominate. So if it does rain over land it will run directly to the pole from there.

The reshaping of the Earth back to hydrostatic equilibrium will take orders of magnitude longer than a human time scale: civilizations will rise and fall and new species will flourish while the globe is still seriously oblate. Think about the present-day rate of convection and plate techtonics: this reshaping will be far more rapid movement than existing plate movement, which is still enough to cause earthquakes. So moving forward, expect faults to appear and the crust to try to accommodate to the new shape, an order of magnitude worse than existing earthquake-prone regions. On the immediate scale, it might take years for stress to build up, with cemtimeters of settling before something gives. OTOH it won't be one piece of crust moving cm relative to another: it all moves together. Rather, the overall shape has to change, so this may be concentrated at places where it cracks. You'll get thrust/subduction movement at these new faults in response to the change in circumference rather than the change of height per se.

  • $\begingroup$ No, look at the shape of the Earth. I looked it up to get the actual value when I wrote the post. The equator is > 20km farther from the centerpoint of the planet than the poles. That is, a tall mountain. $\endgroup$
    – JDługosz
    Mar 18, 2016 at 10:15
  • $\begingroup$ Corect! I read to quickly. Equatorial GROUND willbe (temporary) higher than the sea. An important point is that the water rushing away from the equator would flow to the poles. Ocean could raise there by several km (especally as it woud create a kind a gigantic 20year long tsunami) and liquify the whole of the ice cap $\endgroup$
    – Madlozoz
    Mar 18, 2016 at 10:23
  • $\begingroup$ Also, note that it takes millions of years for the rock to reshape, not just a few. The ground is still rebounding from the removal of glaciers of the ice age, for example, and it's been what 50000 years? $\endgroup$
    – JDługosz
    Mar 18, 2016 at 10:27
  • $\begingroup$ Also note this doesn't say anything about the frequency of this rebond. It only says that the wave have a relatively low atenuation. This is logic given the mass of the earth. So it mean the ground will occilate betwin +20km and -20km over a ?? year period for a VERY long time. FUN! FUN! FUN! $\endgroup$
    – Madlozoz
    Mar 18, 2016 at 11:55
  • $\begingroup$ I thought the equator was currently 20km higher than the poles? that means that without rotation, it'd be 20km lower than it currently is. However, since the ocean is subject to the centrifugal force (or lack thereof) too, I doubt there will be a lot of disturbance coming from that direction (except probably a lot of high waves while the ocean tries to deal with earth slowing down). Well, unless you stop from one moment to the other. Then good night humanity. $\endgroup$
    – subrunner
    Mar 18, 2016 at 14:19

A few effects:

Massive hurricanes. With one side of the planet receiving all sunlight, the hot air on the light side will wind to the dark side from above, and cold air on the dark side will wind to the light side from below; a circulation loop in global scale, west-east instead of current north-south; see Atmospheric Circulation (Wikipedia) for details.

Most plant species wouldn't survive, since not only photosyntesis is disabled, but the temperatures will be more extreme in any given place. My guess is a sort of movable temperature gradient: the current center of the dark side is the coldest region, much alike the current North Pole, the current center of the light side is near the boiling point for water, and the region near the light/dark divide is livable, although rather windy.

People would need to adapt quickly: movable homes, movable farming, heat- and cold-hardened permanent structures (like most industries), worldwide shipping for moving beyond the continents.

I imagine great home/farm trucks rolling along roads, and anchoring, like ships, on the earth before the next tornado strikes.

  • $\begingroup$ The land ships is a nice image $\endgroup$
    – christutty
    Mar 19, 2016 at 5:17

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