What If… the world was round?

What If is (yet another) new series here on Universe Factory. We take a question that was asked on Worldbuilding Stack Exchange and closed because the what-if format is too broad for the site, and do some analysis of it here instead.

What if the world was round? Not “round” like it is now, but round — perfectly round. No natural aberrations at all (apart from things like flora). What would happen?

First, let’s define some limits. A round world is one where the surface is a perfect sphere, discounting:

  • animals, including humans;
  • buildings,
  • plants.

Additionally, natural processes like tectonic activity don’t affect the round-ness of the planet.


The first thing I can think of being affected is water. Assuming that the Earth developed like this, and it didn’t just happen overnight, then oceans would never form.

A world that developed perfectly round would be all land. Every last inch of it. There wouldn’t be lakes, rivers, or oceans, because the gorges they develop in wouldn’t exist.

Instead, when it rains, we’d see the land soak it all up — much like it does now, but all the rain would have to be soaked up. Which leads me onto an interesting thought, actually — would it rain at all?

Rain is part of the water cycle, which looks like this:

Okay, that’s quite a lot simplified, but it’s all we need. Water gets into the sky, and thereby into clouds, because it evaporates from the surface of oceans, lakes, and rivers. Large above ground water bodies have to be present for this to happen.

In our new flat Earth, we don’t have any of those. Since the water is all absorbed into the ground, we don’t get rain.

No Rain?

Yeah, no rain. That’s generally not considered to be a good thing. However, whether the human race survives or not again depends on what time period we’re talking about. If this just happens one day, we’re fine because the oceans stick around.

But let’s get further into this — now I’m interested.

In scenario number 1, the world developed flat. There are no oceans, no lakes, no rivers. Life never starts here, because life here started — you guessed it — in the oceans. Status of human race: nonexistent.

In scenario number 2, the world suddenly becomes flat overnight. The oceans are still here, but they’re at the same level as all the land, and rivers and lakes are now just extensions of ocean, instead of running into them. In this situation, we’re okay for a while, because we still have access to water. However…

Natural Disasters

Natural disasters are now far more threatening to the human race. Hurricanes and flooding from the sea are far more damaging: since the land is now at the same level as the sea, floodwaters will come in much further and much faster, and in greater volumes. That’s going to cause a lot of damage to coastal areas. There’s also the potential outcome that the water doesn’t recede again, because there’s no slope to direct it.

Earthquakes, let’s look at those. They’re going to have a pretty similar effect on coastal areas. An earthquake in an inland area won’t be much different to the earthquakes of today, but an earthquake at sea that causes a tsunami — even a tiny one — will wreck coastal towns and infrastructure to far further distances inland than could ever happen today.

Geological Activity

I mentioned earlier that plate tectonics wouldn’t affect the roundness of the planet, because… magic. Now let’s come back to that — would there be any tectonic activity?

Tectonic activity is the movement of (unsurprisingly) tectonic plates that make up the Earth’s crust. These plates formed as the Earth did: the Earth was initially a rather hot ball of what amounted to magma. As this cooled down, it cooled with cracks in it. Some of these cracks are small, others are massive — the San Andreas fault line is one of them. These big cracks are the boundaries between plates, and are often the sources of earthquakes and volcanoes.

So, if our Earth formed as a perfect ball, would these plates form and would we thus have tectonic activity? I’m going to say yes — the process of a planet forming results in the initial form of the planet being a hot ball of magma, which needs to cool down to form the Earth we know. I’m assuming the process of cooling doesn’t change at all, so the magma would still cool with cracks in it. They’d have to be sub-surface cracks, for our “perfect sphere” premise to stand, but they’d still form and leave us with tectonic plates.

Which brings us to another interesting idea: volcanoes. When tectonic plates move due to the convection currents in Earth’s mantle, they leave gaps between them. In these gaps, magma can bubble up to the surface (especially if it’s under any pressure), which over time leaves a volcano built from the cooled magma.

We aren’t allowed to have volcanoes, so this leaves us with a potentially bad situation. Volcanoes relieve the unequal pressure inside Earth. Without them, we get pressure pockets where the pressure is far more than it should be. Eventually, enough pressure would cause the surface to simply explode, almost like a reverse sinkhole.

Something tells me that a perfect sphere Earth would not be something to celebrate. When’s the next spacebus out?