Thinking about the end of the world is – scientifically speaking – quite good fun. Setting off all the world’s nukes would be pretty bad for humanity, but if you really want to bring about the apocalypse, setting off every single volcano in the world would actually be a more wholesale form of supervillain-esque destruction.

Thing is, there’s more ways to bring doom to the planet than people realize. So, as it’s International Water Day this week (March 22), we thought we’d bring about the end of the world by removing all of its water.

As you might expect, people would die very quickly without it, but what would happen to the rest of the planet? Would there be anything left except for a dusty shell, or would life, as they say, find a way? Let’s take a look.

The Pale Brown Dot

It’s 2017, and a gigantic fleet of alien explorers has just appeared somewhere between Earth and the Moon. They’ve been a bit silly, you see – by burning too many carbon-rich fossil fuels and pumping out far too much greenhouse gases, they’ve caused their planet’s climate to warm so much that all the water on it has evaporated.

So, they’ve turned up with a big space vacuum cleaner to steal all of ours. For the sake of simplicity, we can say that it has the power to remove water from everything except living things.

With world leaders unable to do anything about it, and the US – with all its military might – responding by Tweeting insults at the alien fleet in all caps, we’re hopeless to defeat the extraterrestrial aggressors.

The first thing we’d notice is that the rivers, lakes, ponds, puddles, and oceans would disappear. All life within them would perish within hours, and the continents we live on would suddenly tower over these newly created basins, most of which would be 3.8 kilometers (12,500 feet) deep.

^{The world would look a lot more like Antelope Canyon. Anton Foltin/Shutterstock}

The Arctic would essentially stop existing, and the hidden bathymetry beneath it would resemble a series of jagged crevasses. The Antarctic, free from its icy duvet, would become a rocky, barren land full of mountains and unfathomably large canyons.

Clouds would no longer hang over the nations of the world, rain and snow would become extinct, hurricanes and thunderstorms would evaporate away into nothingness, and our pale blue dot would be decidedly more brown and green. Weather would be dominated by wind patterns and little else. Sandy deserts would spread across the planet.

Eventually, vegetation would die out. Animal life, including us, would soon follow suit and bite the literal dust.

This, however, is the obvious bits and bobs. You have probably guessed that we’d be completely screwed, but there’s more to the fate of the world than fragile Homo sapiens.

Turn Up The Heat

The oceans are the world’s greatest carbon sink. Forget the atmosphere, much of the thermal energy trapped in the planet’s atmosphere by greenhouse gases gets stored in the world’s oceans. In the past century alone, these gigantic bodies of water prevented Earth from warming an absolutely staggering 36°C (64.8°F), not the roughly 1°C (1.8°F) it experienced in reality.

Planets with too much carbon dioxide and methane and not enough water will likely experience a runaway global warming effect.

Take Venus, for example. It’s geologically very similar to our own world, and once upon a time likely had some surface water. This, however, clearly wasn’t enough to deal with all the carbon dioxide present in its atmosphere, much of which probably came from ancient and powerful volcanic eruptions.

Some of the carbon dioxide was absorbed into the water, but ultimately, the planet got too hot and the water boiled off into space. This left Venus without a significant carbon sink other than the atmosphere, so our neighbor kept warming until it reached its current surface temperature of around 462°C (864°F).

Without any water on Earth after the Great Dehydration attack of 2017, our planet would suffer a similar fate.

Don’t forget that vegetation has died out too. Without plants to convert carbon dioxide into oxygen through photosynthesis, the world would warm even faster.

What Lies Beneath

^{Most of the world's volcanoes would be found in the newly exposed ocean basins. yggdrasill/Shutterstock}

Lest we forget that much of Earth’s water doesn’t merely reside at the surface.

Plenty of it hides underground, within the crust of the tectonic plates that continually drift around, come together, and break apart. Lots of it hides within the mantle, the superheated churning chunk of the planet that makes up 84 percent of its volume. Take away that water too and Earth will become entirely unrecognizable.

You see, when a dense plate moves into a less dense one, it sinks (“subducts”) beneath it. As the mantle heats it up, it dehydrates, and the water evaporates off and rises up into the wedge of mantle between the two plates.

Through a series of volcanological quirks, this sets up a magmatic plumbing system in the crust that produces explosive volcanoes, like the Cascades along the Western United States or Mount Fuji, for example. Without water, this process would not take place and there’d be a lot less volcanoes on Earth. Boo.

Weirdly, the process of plate tectonics would itself be in a bit of trouble. One tectonic plate subducts beneath another because it’s denser, but say you’ve got two plates that are composed of the same material – what then?

Well, they’d probably make like India and Eurasia – two equally dense continental plates – and ram into each other, forcing much of themselves upwards into the sky and forming the Himalayas.

It’s thought that, in a case where two tectonic plates are roughly the same density, one only efficiently sinks beneath the other thanks to the weight of the sediment-filled ocean sitting on top of it.

Without an ocean present, one of the plates won’t be weighed down by any accumulating sediment. It won’t be pushed beneath the other and subducted. Instead, the two plates will keep running into each other.

So, if aliens sucked away all the oceans today, any oceanic plate running into another oceanic plate, or any continental plate coming up against a continental plate, would ultimately smash into each other and form a huge series of mountain ranges.

Essentially, then, if Earth did have all its non-biological water stolen, it would rapidly become a superheated desert world full of continent-sized chasms of death and, eventually, ridiculously high mountains.

Hey there little guy

^{Mexico's Cave of the Crystals, which contains examples of currently unidentified microbial life in states of suspended animation. Alexander Van Driessche/Wikimedia Commons; CC BY 3.0}

Life, however, would find a way. Microscopic life, that is – the type that didn’t need to rely on water to survive.

It’s likely that life needed water at first to emerge – and almost all life today requires it – but as evolution ran its course, microbes known as “extremophiles” have appeared. Unbelievably hot environments, powerful acids, and a lack of sunlight or water actually appear to suit some of these absolutely minuscule lifeforms.

Some of these exist within the crust and thrive, using carbon monoxide to produce nutrients. As a NASA team recently discovered, others hide away in gigantic crystals existing in a state of suspended animation.

So yes, humanity would be doomed if all the water on Earth was stolen. Yes, the planet would be a gigantic desert wasteland with insane topography. Sneaking around in the shadows, though, will be the extremophiles, slowly taking over the world long after the hydrophilic aliens have left.

Maybe they could avenge us.