Helen Czerski (Torva)
WHEN you stand next to the ocean, it is easy to forget that it is connected to every other bit of blue on the planet. If you were so inclined, you could sail from your nearest port through every sea and ocean on Earth without ever making landfall. As ocean physicist Helen Czerski reminds us in her fascinating book, Blue Machine, the ocean is huge, covering 71 per cent of Earth’s surface and containing 96 per cent of its water.
But what we often fail to appreciate is how vastly important it is for the workings of the rest of Earth’s systems, including its atmosphere, ice, land and life. We have a view of our home planet that is still dominated by land and that largely regards the oceans as the salty, wet bits in between.
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This is, of course, not a new observation. Photographs from the Apollo missions of the late 1960s and early 1970s had a profound impact on our view of the planet, inspiring the famous quote-cum-cliché: “how inappropriate is it to call this planet Earth when it is quite clearly ocean”. (Czerski avoids this, probably in the knowledge that, although it is to science fiction writer Arthur C. Clarke, nobody can definitively point to where or when he said it.)
But, in Czerski’s hands, the incredible reality of Planet Ocean really comes alive. Much writing about the mysteries of the deep focuses on its weird and wonderful biodiversity, yet it turns out that the physics of the ocean is just as fascinating. And, while Czerski does throw us plenty of biology bones, this is really a book about the ocean’s physical features – submarine mountains, volcanoes and , deep ocean trenches and the endless abyssal plains – as well as the vast forces that shape the water above them.
Chief among these forces is the heat from the sun, but its light is also involved, as is the rotation of Earth and the salinity and density of the water. Czerski explains how these combine with each other to create a dynamic system that she calls the “blue engine”.
It wasn’t immediately obvious to me what she meant, but Czerski explains that the ocean does what any engine does: it converts one form of energy, usually heat, into movement.
And that engine has a profound impact on the whole planet, including dry land. It controls the weather and climate, provides terrestrial species with food and other resources and creates a life-saving buffer against the wild swings of temperature between night and day and across the seasons. The ocean is, she says early on, “the story that defines planet Earth”, and she really makes good on that statement.
Czerski has a lovely way with words and a knack for a vivid simile – the great ocean basins, she says, can be thought of as a bit like “the hollows in the trays that used to be used for airline food”.
She also knows when to add interesting anecdotes. Did you know that if you cut yourself more than 10 metres underwater, the blood appears green? Czerski does – now. And then there are stories going back to the peopling of the Americas 26,000 years ago.
I also loved the section about Antony and Cleopatra’s final defeat by Roman emperor Octavian at the Battle of Actium in 31 BC. Various ideas have been put forward as to why their fleet didn’t carry out its battle plan, but the most likely explanation is “dead water” – a phenomenon, caused by the layering of ocean water, that can stop a ship in its tracks. On such oceanic behaviour, history can turn.
The framing of the ocean as an engine driven largely by heat is also a clever device for discussing the impact of climate change, which is, after all, says Czerski, “the slow accumulation of extra energy into the Earth system”, 90 per cent of which is absorbed by the ocean.
You can’t inject that much energy into an engine without revving it, and the ocean is now showing signs of veering out of control. But there are solutions – and, according to Czerski, they start with appreciating the ocean for what it is, “the beating heart of planet Earth”.
