Forget a doomsday asteroid or melting permafrost. It’s the freezing of Earth’s core that will end the world in today’s episode. Or would it? Because maybe, just maybe, we could save the world by heating Earth from the inside.
What is happening down in the Earth’s core? What would happen if the core froze completely? And would we have a chance of fixing the Earth before it’s too late?
You’ve probably never noticed that the Earth’s core is freezing. But it is. It’s just happening very slowly.
About 4.5 billion years ago, the entire core was molten. But over billions of years, the Earth has slowly cooled from the inside out, causing parts of its molten iron outer core to freeze.
And if this process significantly sped up in a flash freeze event, we’d need to do something about it. The Earth’s core does more for our planet than you might imagine. Without it, what would happen to you?
Earth has a magnetic field that surrounds it and protects you from radiation. This field is created by, you guessed it, our planet’s core. Heat transfers from the superhot inner core, through the outer core, and into the mantle. This heat exchanging process, called convection, creates a current of liquid metal in the outer core.
And the flow of liquid metal generates electrical currents, which extend into space to form that essential magnetic field. But if Earth’s core were frozen solid, there would be no current in the outer core. And there would be no magnetic field.
All of a sudden, we would have no protection from the ultraviolet radiation bombarding Earth. You’d have no more fun in the Sun, because now the Sun would be deadly. Even plants wouldn’t be able to survive the intense UV rays.
You’d have to grow all your food inside, as if you lived on an alien planet. And you basically would be. Because the Earth’s magnetic field also keeps our atmosphere in place.
Without it, solar winds would strip Earth of its breathable and safe atmosphere. Our planet would start looking more like Mars than the Earth we know and love. But would there be any way for you to escape this fate?
Well, you could jump on a spaceship, assuming those still exist, and leave Earth. But where would you go? Any other planet would be just as hostile as the dying Earth, if not more.
Your best bet would be to dedicate every brain cell you have to help the world reheat the Earth’s core. But could we do it before it’s too late?
We just might be able to. But we’d need to know what made the core so hot before it froze. There are three reasons. The first is leftover heat from the process of accretion, which is how Earth formed.
Basically, Earth was once just a tiny core seed. But it was able to gather more and more material into itself, growing larger and larger. Every time a new material crashed into the growing Earth, it generated incredible amounts of heat, which got trapped inside the core.
The second reason Earth keeps its toasty inner temperature is called frictional heat. When Earth was young, it underwent gravitational sorting. The denser and heavier parts, including iron and nickel, sank into the center. The less-dense substances, like oxygen and water, floated outward. This created friction and generated heat.
The main reason our planet is so hot is because of radioactive decay. As radioactive isotopes decay in Earth’s mantle, they produce heat. But could we successfully reproduce any of these phenomena? We can’t go back in time to when Earth formed. And we can’t create more friction in the core. So we’d only have one method left to try. And that would be by adding more radiation to it. Which means we’d need to drill a giant hole.
But not just any hole. We’d have to drill way down to the mantle, where radioactive decay happens. So we’d drill through the ocean floor, where the crust is usually thinner.
No one has ever drilled into the mantle before. The closest anyone got was back in 2005, when the Integrated Ocean Drilling Program bored a hole 1,416 m (4,644 ft) deep in the North Atlantic Ocean. But let’s say that the world would come together under the threat of impending doom and create the most sophisticated drill ever.
Once we drilled beneath the seafloor, all we’d have to do is pump the mantle full of potassium, uranium and thorium. These elements would decay and generate heat. But would that be enough to reheat Earth’s core?
It could, eventually. But there would be a drawback. All the heat from radioactive decay would be in the mantle, not the inner or outer core. It wouldn’t recreate the life-saving magnetic field. For that, we’d need the outer core to melt.
OK. Back to the drawing board. It looks like we’d need to do something we’ve never done before if we want to save humanity. And this time, we would have to drill all the way to the outer core, 2,900 km (1,802 mi) deep.
Because we’d be building a thousand miles long Ultra High Energy Particle Accelerator deep into the Earth. This particle accelerator would harness the Sun’s power and pump energy into Earth’s outer core. Once the outer core reheats, it would generate the electrical current and create the magnetic field.
But here’s the thing. The pressure inside the inner core is so extreme that iron atoms are not able to become liquid. This is why the inner core is so incredibly hot and solid. The intense pressure would make any tunnel we try to drill immediately collapse.
So even if we could build that very advanced particle accelerator, we wouldn’t be able to use it. At least we would give it our best shot. Maybe you should’ve hopped on that spaceship. Yet again, the freezing of Earth’s core would be death to us all.
Luckily, scientists estimate that it would take 91 billion years for the core to solidify completely. And seeing how the Sun will become a red giant star in 5 billion years, the Earth cooling is the last thing you’d need to worry about.
- “Earth’s core is melting … and freezing”. sciencedaily.com
- “What Are Convection Currents?”. Herb Kirchhoff 2021. Sciencing.
- “What creates Earth’s magnetic field?”. Vejayan, Vishnu. 2017. Cosmos Magazine.
- “Curious Kids: What Would Happen If The Earth’s Core Went Cold?”. 2018. The Conversation.
- “Why is the earth’s core so hot? And how do scientists measure its temperature?”. American, Scientific. 1997. Scientific American.
- “Probing Question: What Heats The Earth’s Core?”. 2021. phys.rg.