Draining the oceans

Dear Evil Engineer: Could I drain the oceans and provide land for all?

Image credit: Dreamstime

This month, the Evil Engineer examines whether Earth’s oceans could be stashed away somewhere for convenience.

Dear Evil Engineer,

I am director of a global management consulting firm. I recently secured a contract to compile a report on leveraging emerging technologies to settle territorial disputes (‘Breaking New Ground: Territorial Dispute Resolution in the Digital Age’). I admit ending territorial disputes is not strictly aligned with our brand values, but it was too lucrative an opportunity to turn down.

Anyway, I brought together my band of bright graduates – none of whom have any experience in the sector, but all of whom really know how to use a fish knife – for some out-of-the-box thinking on the problem. One consultant suggested generating and allocating virtual, non-fungible territory in the metaverse to compensate for real-world territorial concessions. This was unfortunately shot down by our conservative-minded client. Still, it got us thinking: why shouldn’t we create more land in the real world, so everyone can have all the land they want? If we could simply clear Earth’s oceans, we would have plenty of land to go around, ergo, no more territorial disputes.

Could you advise me on how to drain the oceans?

A confident villain

Dear villain,

You may be interested to hear that you are not the first to propose such a scheme.

In the first half of the 20th century, the German architect Herman Sörgel devised and promoted the delightfully batty ‘Atlantropa’ project. By building five massive hydroelectric dams at key points around the Mediterranean Sea – including one in the Strait of Gibraltar to shut off the Atlantic Ocean – the sea could be lowered by 200m, connecting Europe and Africa and creating a gigantic continent for Europeans to collectively colonise. If there was only more land, the theory goes, there would be no need to fight over it. The idea didn’t stand the test of time for many reasons – although technical impossibility was not among them. If your client is in a position to secure trillions in funding and a significant fraction of global concrete production for dam-building, part-draining a sea is a real possibility.

Draining the oceans is a much more extreme proposition.

As it happens, the oceans are being drained naturally already. Every day, great volumes of water pass into the Earth’s mantle as part of the deep-water cycle, with much of this water remaining sequestered inside the Earth. Geologists from the Tokyo Institute of Technology proposed in a 2019 Geochemistry, Geophysics, Geosystems paper that the oceans are being drained five times faster than they are being replenished (1.12Gt draining into the mantle each year compared with 0.23Gt being pushed back to the surface via hydrothermal vents and underwater volcanos). The paper estimated that this process has lowered sea levels by 50-130m over the past 230 million years. At this rate, it would take approximately a billion years for the oceans to drain.

Draining the oceans

Image credit: Dreamstime

Can this be sped up to a useful timeframe somehow? It seems unlikely. Even detonating our most powerful nuclear weapons on the ocean floor in an effort to ‘crack’ it open would be utterly feeble – akin to throwing conkers at a tank in the hope you might break through its armour.

If we can’t hide the oceans inside the Earth, how about in the sky? Let’s consider the feasibility of boiling the oceans dry, ignoring the messy reality of what happens when a colossal quantity of steam is pumped into the atmosphere. The mass of Earth’s oceans is around 1.37x1021kg. The temperature of the water varies from below 0°C in the depths – its salinity lowering its freezing temperature – to above 20°C at some places at the surface. The temperature at which it boils also varies due to pressure. For the purposes of calculating a ballpark figure, let’s say we need to raise the temperature by 100K. The specific heat capacity of seawater is 3,850J/kg/K, and the latent heat of vaporisation is 2.3x106J/kg, so the energy required would be: 1.37x1021x(3,850x100 + 2.3x106) = 3.69x1027J. That’s the equivalent of almost 40 million years of global electricity production.

What we can take away from these disappointments is that the oceans are simply too vast for us to vanish by draining or boiling. Other engineering solutions – such as pumping the oceans into space to sequester there – require similarly implausible quantities of energy. The most likely means through which the oceans will be vanished is via some cataclysmic natural event. For instance, a gigantic coronal mass ejection could strip away the Earth’s atmosphere and all the oceans with it, in a similar catastrophe to that which scientists theorise stripped the gas and water from Mars.

The extreme difficulty, time and cost that would be involved in lowering the oceans has been acknowledged by scientists to make the case for combatting climate change rather than fighting impacts of climate change through such megaprojects. The Northern European Enclosure Dam thought experiment, for example, estimates that up to half a trillion euros and 100 years of construction would be required to build a dam between Cornwall and Brittany to combat rising sea levels in Northern Europe. It is intended to be taken as ‘more of a warning than a solution’.

I don’t want to sound discouraging because, while draining the oceans is impossible, it is entirely possible to redraw the map. For instance, lowering surface temperatures – either through old-fashioned decarbonisation or geoengineering – would lock up water in the poles and significantly lower sea levels. If that sounds too much like do-gooding, you can always get building across the Strait of Gibraltar.


The Evil Engineer

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