By Callum Roberts

[Note: The following is the opening section of the new book The Ocean of Life: The Fate of Man and the Sea, by Callum Roberts. It is reprinted here by OpenChannels with permission from Viking Press.]

The water felt chilly as I waded out to fetch the battered skiff from its mooring. It slid easily over the glassy lagoon to the beach, where Julie waited with our diving gear. We had been married a month, and in lieu of a honeymoon I had persuaded her to accept two months of fieldwork studying fish behavior on this remote patch of Australia’s Great Barrier Reef. It was June 1987, winter in Australia and summer back home. Two herons picked their way along the shoreline looking for breakfast. They flapped off as the outboard engine coughed to life, and we set course for a spot a mile away, across a maze of coral so complex that it would have baffled the most capable navigator.

We anchored on a rubble ridge that separated the lagoon from the open sea. This was our first ocean dive here, and the thrill of expectation was tempered by a frisson of fear. Ahead of us the homely greens and browns of the shallow reef gave way to the dark indigo of the deep. Huge buttresses of coral plunged down hundreds of feet in parallel walls separated by deep channels. Vivid purple finger-corals vied for space with yellow lettuce-coral, while great mounds of blue and green polyps rose from the bottom.

The reef was a confusing swirl of movement, like Grand Central Station at rush hour. Stocky surgeonfish with electric blue stripes raced around purposefully while loose groups of gaudy parrotfish dodged them. Clouds of damselfish and anthias hovered above, delicately plucking invisible food from the water. Along the edge of the reef I counted eight loggerhead turtles, one for each buttress in view. A gray reef shark headed our way but barely acknowledged us as he passed by. The whole scene felt timeless and primordial. I was transfixed.

I wonder what I would have thought if on return to shore we had been greeted by a curmudgeonly sage who prophesied that in one hundred years this magnificent reef would be a crumbling ruin, that its bright coral escarpments would be replaced by green fuzz, and that the ranks of fish would have thinned and given way to swarms of jellyfish and gelatinous plankton. I would probably have thought him mad. Nothing could have seemed less likely. And yet less than twenty-five years later most serious marine scientists predict just such a fate. We can already see it happening.

Eleven years after our honeymoon dive, in a foretaste of a warmer world to come, the oceans heated so dramatically that a quarter of the world’s coral died. In much of the Indian Ocean 70 percent to more than 90 percent of all corals died, taking with them countless creatures who used coral for living space or food. If three quarters of our forests had withered and died that year, people would have demanded to know why, and aggressive plans would have been drawn up for their recovery. Yet this global catastrophe passed largely unseen and unremarked outside the world of marine science.

The world’s oceans have been very stable for most of civilized history. Since the seas leveled off six or seven thousand years ago, after the last ice age, they have for the most part been predictable. Yes, coasts have retreated and advanced under the relentless influence of wave and tide, but the oceans themselves seemed changeless. Their constancy contrasted with the world above water, where landscapes underwent dramatic alterations as first pastoralists and agriculture spread, and then later cities and industry. Today it is the turn of the oceans.

This is a book about the sea change unfolding around our planet. In the last half century human dominion over nature has finally reached the oceans. The speed and extent of these changes has caught us unprepared. The sea is becoming more hostile to life, and not just for the creatures that swim, scuttle, or crawl beneath the waves, but for us too. Only in the last decade or so have we begun to recognize how our activities are reshaping the oceans, and what that means for our own well-being.


We have long known how humankind has changed the land, modifying landscapes to suit our needs and affecting its wildlife across thousands of years. Tens of thousands of years, if you consider Australian aboriginals and Native Americans used fire to clear vegetation and facilitate hunting and gathering. But we persist in believing, as to paraphrase Byron in the epigraph to this book, that humanity’s dominion stops at the sea. Yet even in Byron’s time human impacts on the sea were significant. The great auk stood two decades from extinction and the Atlantic gray whale had vanished forever. Fishing had begun to deplete stocks close to coasts and damage habitats with trawls and dredges. People were throwing up coastal defenses, and large areas of marsh and estuary had been reclaimed for ports and agriculture. Rivers in populous regions filled coastal estuaries and bays with mud washed from land exposed by the plow.

Our influence has grown exponentially since then. The last two hundred years have seen marine habitats wiped out or transformed beyond recognition. And with an ever accelerating tide of human impact, the oceans have changed more in the last thirty years than in all of human history before. In most places the oceans have lost upward of 75 percent of their megafauna — large animals such as animals, dolphins, sharks, rays, and turtles — as fishing and hunting spread in waves across the face of the planet. For some species, numbers are down as much as 99 percent as is the case for oceanic whitetip sharks of the high seas, American sawfishes, and the “common” skate of Northern Europe. By the end of the twentieth century, almost nowhere shallower than three thousand feet remained untouched by commercial fishing and some places are now fished to ten thousand feet down.

The oceans have been our conduit for commerce for thousands of years. Today they are the highways of a globalized world, and the roar of engines can be heard in every corner of the sea, even beneath polar ice. Increasingly they also provide us with oil and gas, and growing scarcity has driven us to venture deeper and farther offshore. We are within a decade or so of the onset of deep-sea mining. Riches beckon in the blackness of the abyss, miles below. Dark nuggets of precious metals and rare earths lie scattered over the bottom, seamounts are crusted in cobalt, and deposits of gold, silver, and manganese spewed forth from superheated springs are nearly within reach of miners.

Why, in the face of widespread evidence of human impact, do so many people persist in thinking that the oceans remain wild and beyond our influence? The answer lies in part in the creeping rate of change. Each generation forms its own view of the state of the environment. Younger people generally fail to perceive changes experienced by the old, and so knowledge of past conditions fades with time. Younger generations are often dismissive of the tales of old-timers, rejecting their stories in favor of things they have experienced themselves. The result is a phenomenon known as “shifting baseline syndrome”: we take for granted things that two generations ago would have seemed inconceivable.

Loren McClenachan unearthed a telling example of shifting baselines in the archives of the Monroe County Library in Florida when she was doing research there as a doctoral student at Scripps Institution of Oceanography. She found a series of photographs of fish catches landed in Key West by one recreational fishing charter company between the 1950s and the 1980s. She extended the series into the twenty-first century with her own pictures at the same dock. In the 1950s, huge goliath groupers and sharks dominated catches, many of them bigger and fatter than the anglers. As the years pass by the fish shrink, and groupers and sharks give way to smaller snappers and grunts. But the grins on the anglers’ faces are just as broad today as they were in the 1950s. Modern-day tourists have no idea that anything has changed.

The oceans are changing faster than at almost any time in Earth’s history, and we are the agents of that transformation. Many of these changes will test the ability of its denizens to survive into the future. These alterations are also reshaping our own relationship with the sea and threaten many of the things that we most cherish and take for granted. Our failure to notice creeping environmental degradation has compromised more than our quality of life. In extreme circumstances, it threatens human welfare. History offers many examples of civilizations that have been destroyed by environmental catastrophes that they have unwittingly brought on themselves. Easter Islanders cut down all their trees to raise statues to their gods and then starved when their soil dried up. Mesopotamians invented sophisticated irrigation agriculture, but the technique eventually left fields so salty they could no longer grow crops. Mayan hillslope farming practices stripped the region of its topsoil, precipitating the collapse of this extraordinary civilization during prolonged drought. In these and many similar cases the adverse effects were local to an island or region. Today our influences are global, and we will have to act globally to reverse the impact of what we have already done.


I began my career studying coral reef fish. From the moment I first dived a Red Sea reef, I was hooked. (My wife, Julie, was similarly hooked by our honeymoon trip to the Great Barrier Reef, and she also became a marine biologist.) Thirty years on fish are still at the heart of my research, but my outlook has expanded to a much wider interest: the relations between people and the sea over the course of history. Nonetheless, when I began the research for this book there were huge stretches of ocean science of which I was only dimly aware. Scientists are specialists and devote their lives to research within narrow fields that become further constricted as time passes. Each pores over a fragment of the world, turning it over and over in his or her mind like a chip of some mosaic. Management of pollution is segregated from that of fisheries, which in turn are rarely considered in the same place as shipping or climate change. This means that impacts are discussed in isolation at different meetings and by different people, who never quite see the overall picture. I decided to write this book because I felt there was an urgent need to bring all these separate fiefdoms together. What I found along the way has been a revelation.

We fear change and resist it. Perhaps that resistance is hardwired into our genes: the familiar seems safer than the unknown. Many animals go to strenuous lengths to return to the place where they were born to breed, probably because past success there gives greater assurance of future success. This is a dynamic world, and change sometimes brings good things; but some changes, notably those which erode resilience, are harmful, for when resilience is worn away all bets for the future are off. The path we are on today, as I will show, is pushing ocean ecosystems to the edge of viability. We are emptying the seas of fish and filling them with pollution heedless of consequences, and our unplanned experiment with greenhouse gases is gradually infiltrating the deep sea.

Although a few of the human influences that I will describe in this book have been underway for centuries, others have really only taken hold in the last fifty years. In this sense our impacts on the oceans have been sudden — instantaneous, almost — given that they have taken less than one thousandth of the hundred and fifty thousand years or so for which modern humans have existed. The response demanded to counter these impacts will also have to be sudden and global in scale. Few people yet grasp the gravity of our predicament.

In this book I will take you on a voyage beneath the waves to reveal the seas as few know them. I will show how human activities have for centuries been unpicking the fabric of marine life. We have been able to ignore much of the harm done by our heedless use of the sea — until recently. But as the scale and intensity of human influence have grown, the rate of change has accelerated, and we must now confront the consequences.

To understand the present we must first know the past. I begin at the beginning, when the world began, before picking up our own story, when humankind first makes its appearance on Earth. For tens of thousands of years our only real impact on the oceans was the removal of fish and shellfish, so I start with a brief history of hunting and fishing, and how they have evolved through time. The Industrial Revolution heralded the emergence of people as agents of planetary change, and I move on to describe how the use of fossil fuels, and their impact on currents and climate, is transforming the sea in ways not seen for hundreds of thousands or millions of years. Sea levels are rising faster than the highest rates predicted only twenty years ago. They now threaten dozens of the world’s great metropolises, and within fifty years could inundate vast tracts of our best agricultural land, imperiling food security. Within the seas themselves, in one of the least known but potentially most damaging effects of greenhouse gas emissions, acidity is going up in step with carbon dioxide. The outcome could be catastrophic. Shell-forming animals, including many that sustain ocean food webs and thereby our own fisheries, will find their lives increasingly difficult. Not for fifty-five million years has there been a disruption of comparable severity to the calamity that lies just a hundred years ahead if we fail to curtail emissions fast.

By absorbing heat the oceans have so far spared us the worst of global warming. But warming seas have set life on the move, so in the years to come the fortunes of some fishing nations will wane as others rise. Warming will have far more grave effects on productivity, driving it to excess in some places while turning others into oceanic deserts. If the only threats to life in the sea were climate change and fishing, matters would be bad enough. But ocean life faces other pressures, like pollution. I survey the effects of pollutants ranging from toxic chemicals and the now ubiquitous plastic to sewage and fertilizers, and to less familiar pollutants, such as noise and invasive species. Pollution problems have grown in severity with time, so much so that in many regions we see the emergence and spread of dead zones as oxygen is sucked from the water by decaying plankton. The cocktail of human stresses is mixed differently from place to place, but the result is the same: their effects in combination are far worse than in isolation. We are transforming life in the sea, and with it undermining our own existence.

This book is not a catalog of unavoidable disasters ahead. There is much we can do to change course, if we take the opportunity now, but time is of the essence. The longer we ignore the problems, or prevaricate, the less leeway we have to avoid the direst of our possible futures. I devote the rest of the book to how we can plot a new course to safeguard the oceans and ourselves. What we need, I will argue, is an ambitious plan to reverse long-term trends of depletion and degradation, recapitalize the value of the oceans to people and wildlife, and improve the quality of everyone’s lives, especially of generations to come. We don’t have to look on helplessly as all that we love about the sea is sullied. Change for good is within our reach.

The preceding is from The Ocean of Life: The Fate of Man and the Sea, by Callum Roberts. It is reprinted here by OpenChannels with permission from Viking Press.

Callum Roberts is a marine scientist and conservationist at the University of York in England and the author of The Unnatural History of the Sea, which won the Rachel Carson Environmental Book Award and was chosen by the Washington Post as one of the Ten Best Books of the Year. A frequent keynote speaker at environmental conferences (including Mission Blue, TED, and the Skoll Fondation’s forum on social entrepreneurship), he both advised and was featured in The End of the Line, a documentary on the global fishing crisis, and appeared in the National Geographic documentary America Before Columbus. He was also an adviser on The Wild Ocean IMAX movie. He is on the board of Seaweb and provided the scientific basis for the creation of the world’s first high seas protected network.