We are all used to the lush green landscapes and rugged mountainscapes that define the land we live on, but from space, it’s clear that we live on a blue planet. Despite its extreme saltiness, unpredictable nature and unprecedented effect on our weather, this incredible expanse of water is vital to all life on Earth.
Helen Czerski, a British oceanographer and broadcaster, has spent her career studying the ocean. In her new book “The Blue Machine: How the Ocean Works” (W. W. Norton & Company, 2023), she explores how the huge mass of water that surrounds our planet created the world we live in today, why some places are abundant with life while others aren’t, how civilizations formed around the ocean currents, and why it acts as Earth’s battery, powering its weather systems.
In this interview, she spoke to us about what drives this ocean engine, compares it to a fancy cocktail, and explains what the next great ocean frontier is:
The definition of an engine is something that turns any heat energy into movement, which is what the ocean does.
There’s a warm layer on the top, which can be up to 100 meters [330 feet] thick, and there’s the water below which is much colder, and has itself got layers within it.
But although the top and the bottom of the ocean are sort of separated, there are these plug holes near the poles where they’re connected, and that connection drives the circulation where water goes down, slithers along the bottom of the ocean for a few hundred years, and then comes back up somewhere else.
That’s what the engine is doing on its biggest scale, moving heat from the equator to the poles. This physical engine, with all of these features and all of this anatomy, is what makes things happen, and then animals and humans are influenced by the results. The whole shape of Earth’s civilizations are kind of shaped by what the ocean engine does.
Obviously the biggest question is how it’s going to change under climate change. There are huge questions about how the things the ocean carries, like oxygen, for example, will change as a result of the ocean engine changing shape because it’s got extra energy, it’s changing what it’s doing. So if you slow down that circulation, you change the amount of oxygen, and in the deep ocean that’s going to matter for anything trying to breathe it, for example.
So yeah, I think there are still big dramatic questions, but we have to be pragmatic. We have to understand how the whole Earth machine works, so that we can work with it and not against it, that’s what we’ve failed to do so far.