What If Earth Didn't Have Oceans? | Unveiled

What if Earth Did Not Have Oceans?

Almost 97% of Earth’s total water is in the five oceans. It’s one of the most important substances in the universe, necessary to support all life that we know of. Without water, a human will die within three days. But what if that life source didn’t exist on our planet?

This is Unveiled, and today we’re answering the extraordinary question; what if Earth did not have oceans?

At least three of the four inner planets currently have or have previously had liquid water. Earth, of course, has a vast supply of water, but Venus and Mars likely had surface water once upon a time. In fact, Venus may have been habitable for billions of years, far longer than our most generous estimations for the previous habitability of Mars. As well as that, there’s still water ice on Mars and there are water ice deposits on the Moon and some water molecules. Further out, both Saturn and Jupiter have icy moons – Enceladus and Europa, respectively – that could hide huge, subsurface oceans. So too might another of Saturn’s moons, Titan. Titan even has some kind of liquid cycle on the surface that includes clouds, lakes, and rivers, although these are thought to consist of methane and ethane. Earth is still extremely unique, however, and its water is the key ingredient in creating and supporting the tremendous biodiversity we enjoy here. We’ve got roughly 8.7 million unique species living on our planet in the twenty-first century, and without water, that just wouldn’t be possible.

But it’s true that Venus and Mars could have had just as much biodiversity at one point in time, and neither is capable of supporting native life anymore. In this way, there is a precedent in the solar system for habitable planets suddenly – or, perhaps not so suddenly – having this important resource ruthlessly removed. It’s not clear what happened to Mars to render it the barren wasteland it is today, but Venus’s transformation into “Earth’s Evil Twin” happened because of a runaway greenhouse effect. This effect likely wasn’t caused by any long-dead civilization burning fossil fuels, but was a result of catastrophic volcanic activity. Eventually, Venus’s atmosphere became so dense following large releases of CO2 that now, its surface temperature is hot enough to melt lead. If something like this happened on Earth, then all of our surface water would quickly evaporate. An ocean-less Earth really would just be Venus or Mars.

But what about if our oceans simply disappeared one day as if by magic, rather than being the result of an ecological collapse? The oceans are hugely important to regulate the planet’s temperature, and without them, it would be difficult – if not totally impossible – for Earth’s climate to stay within a habitable range. The only good news is that most of humanity’s actual drinking water does not come from the sea. That’s because the salt in seawater is difficult to distill out thanks to strong molecular bonds; it’s certainly possible, but it’s so energy-intensive that it’s not a method currently used. Drinking water actually comes from reservoirs and rivers because it needs to be fresh water. There is fresh water in the oceans, in fact, there are over 700 trillion gallons of fresh water along the US’s east coast hidden at the bottom of the Atlantic, but we don’t use it for our water supply. In any case, this freshwater would be gone as well.

There are problems, however: most of the water in the world is connected. “Estuaries” are a specific part of Earth’s geography where freshwater and saltwater meet and there are thousands of them. So, where would the magician who removed Earth’s oceans draw the line? Would any body of water somehow connected to an ocean also vanish? If so, we’d see the loss of many rivers and lakes; all five of the North American Great Lakes eventually connect to the Atlantic Ocean, though we likely would not see the loss of the Caspian Sea, Earth’s largest lake. That’s because the Caspian Sea is an “endorheic basin”, meaning it doesn’t drain into the sea. However, much like the ocean, the Caspian Sea contains too much salt for it to be used effectively as a drinking water supply. Earth also has some underground waterways, however, including rivers and lakes contained beneath the surface. A third of our drinking water is drawn from these sources, called groundwater, and this would also remain intact without the oceans.

So, we would still have a water supply. But it wouldn’t last for long without the seas. The water cycle is vital for keeping up the volume of water not only in the ocean but in all the lakes and rivers. Water evaporates, goes into the atmosphere, condenses into clouds, and falls back to Earth as rain, irrigating the ground and helping crops to grow. Even though we can’t easily drink the oceans, they are still the most important part of the water cycle. Without that 97%, we would eventually have no clouds, no rain, and the lakes and rivers we still have would begin to drain slowly into the desolate ocean basins and dry up completely. We do have water already in water treatment plants and the sanitation system that we could stop from evaporating, but it’s highly likely that water would become an even more valuable resource than it is already. Water prices would rocket, which could leave even more people unable to access clean drinking water – bearing in mind that already, 1 in 3 people on Earth don’t have this. Plus, our water treatment would need to become even more efficient: a 2017 report found that 80% of wastewater from all sources – from ordinary household waste to the agriculture industry – does not get reused, it gets pumped into the oceans as sewage. This would absolutely have to change to keep up with water demand; not a single drop of water could be wasted.

The loss of the oceans would also be absolutely devastating to the environment. Earth’s oceans are home to so numerous species, many of which provide us with vital food and nutrition, and these would all be gone if the oceans were to disappear. About fifteen percent of all Earth’s species live in the seas, but creatures that rely on them would die off as well – sea birds, for instance, which live on land but prey on fish. Worst of all, 50-80% of Earth’s oxygen comes from oceanic plants and algae. A greenhouse gas effect like that on Venus would take hold of the planet with so little oxygen to balance out the amount of CO2.

We would be able to solve a lot of mysteries, however. Finally, we’d know for certain whether Atlantis exists; while there’s no evidence that it does, plenty of people still believe it’s out there, and we’d be able to put this to rest. We’d also be able to solve many disappearances, like the ones over the Bermuda Triangle. All those lost ships and planes would be significantly easier to find, now totally exposed by the lost water. We might even learn what happened to Amelia Earhart if her plane was lost in the sea somewhere and not a remote island. Sacrificing the oceans definitely isn’t worth finding out the answers to these questions, but if it’s already happened we may as well investigate.

But what if Earth’s oceans didn’t disappear? What if they simply never existed? Well, given what we know about Venus and Mars, this seems unlikely; if both of those planets had liquid water at one point, Earth probably always would as well. The fourth inner planet, Mercury, is far too close to the sun to have ever supported surface water, however. If Earth had never had water, we simply wouldn’t be here and life would have never been able to form. There is a very good reason why water is the first thing we look for when we try to find life in other parts of the solar system and the wider universe. It’s something necessary for life, and the two elements that make it up, hydrogen and oxygen, are two of the six primary chemical elements needed. As far as we are aware, no life – and certainly not carbon-based life – can survive without water. It’s true that there could be non-carbon-based life somewhere in the universe, but there’s no telling what it would be like. It would probably still have its own set of important elements it depends on, potentially also including H2O.

Earth’s oceans are unfathomably important to life on our planet, and without them, our home would be a desolate wasteland with no way to support any organisms. And that’s what would happen if Earth did not have oceans.