The Ocean of Life: The Fate of Man and the Sea

"Yes, it’s a moving—and at times heart-breaking—summary of how humans have had a devastating impact upon the planet. Over the space of a few hours of reading, Callum Roberts offers us a very good impression of all the changes that are happening to the oceans today. He has made an in-depth study of the history of fishing, and environmental pollution. He charts chemical changes, ocean acidification, and global warming: he shows how the oceans are warming and visibly expanding through the extra heat. He also outlines the drastic biological changes that have occurred, and the way in which humans have become the top predator not just on land but in the sea. Humans have removed most of the other top predators, and fundamentally refashioned the ecological web of the oceans. Because we humans are putting billions of tonnes of carbon into the air each year to drive our lives, we have—as is well-known—created global warming. We have warmed the planet by just over one degree so far. Luckily for the climate, but not so luckily for the oceans, part of that carbon is dissolved in rainwater to form carbonic acid, or dissolves directly into the oceans from the air. As a consequence, the oceans are now measurably acidifying. They are one-tenth of a pH point more acid than they were a century or so ago. This doesn’t sound very much, but as it’s a logarithmic scale, it means its actually thirty per cent more hydrogen atoms drifting around in the oceans. These hydrogen atoms cause chemical mayhem on subtle systems like the physiology of animals, or the shell-building abilities of shellfish and corals. Combined with warming, ocean acidification poses a great threat to plankton and to coral reefs. Even over the last couple of summers, the warming effect has been destroying the corals of the Great Barrier Reef in Australia. As a long-term problem, this is something that would take thousands of years to get back to normal. It’s one of the major issues of current human-driven global change. This is a problem, rather like that of ocean acidification, that has crept up on us. It stems from an Anthropocene phenomenon: the post-war invention of plastics. Plastics are wonderfully useful. They’re durable and don’t degrade easily, and bacteria microbes can’t easily eat them. Yet plastics can very easily get washed from the land into the sea, and once they’re there, because they are so light, they simply float and travel enormous distances. They end up in stagnant patches in the middle of oceans, in what are called ocean gyres. Nowadays, there’s more plastic in some parts of the oceans than there is plankton. Eventually, the plastic will go to the floor of the ocean, because plankton will colonise it and weigh it down, or something will eat it and either excrete it, or the animal will die and drift to the sea floor carrying that plastic with it. But before that happens, the plastic can remain in the oceans for years, decades, perhaps even centuries. It’s a major hazard for any sort of larger macroscopic life, such as fish, turtles, and sea birds. “If we are to avoid our world becoming even more conspicuously plastic-covered, then we’re going to have to experiment, and put into action a range of measures.” Yes—I think it’s important to propose solutions as well as to identify problems. With plastic, we’re at the stage where there is a ferment of ideas about what to do. Some people have suggested great booms or sweeps that filter out plastic from the sea. Perhaps more practically, others have proposed using plastic instead of tar to build roads: that is happening now in places like Scotland and India. Again, putting a charge on plastic bags in shops and supermarkets has been hugely effective in reducing their use. Clearly, if we are to avoid our world becoming even more conspicuously plastic-covered, then we’re going to have to experiment, and put into action a range of measures."