Atlantic

by Simon Winchester

  To dramatize this creature’s importance, it can reasonably be claimed that one in every five breaths any human being takes contains oxygen created out at sea, and quite specifically by Prochlorococcus. We now know it exists, and it goes without saying that if anything disastrous were ever to befall it, the survival of all beings that require oxygen would be placed at risk. In the two decades since Prochlorococcus was found, a great deal of research has been done to see what might harm it, and how. Specifically, researchers have been trying to determine whether the warming of the seas might limit its ability to absorb carbon dioxide and frustrate its propensity for creating oxygen.

  It turns out that Prochlorococcus seems thus far happily resilient to the warming of the planet. It likes warm seas and flourishes in them. Any increase of the sea’s temperature might well cause the range of Prochlorococcus to expand into the newly warmed waters, to push beyond the present day’s 40-degree-latitude lines—and that might have its own effect on not just the outward flow of oxygen into the atmosphere, but on the absorption of carbon dioxide already in it.

  It is tempting—but entirely fanciful—to imagine that such a development might balance some of the expanded emissions of greenhouse gases that are so troubling humankind today. An expansion of the range and population of Prochlorococcus might well turn out to be a component of the earth’s self-regulating mechanism, so crucial to James Lovelock’s famous Gaia theory—which holds that the world is to be viewed as a self-contained living being, able to change its own ways and to deal with its changing circumstances. This curious animalcule might be even more precious than at first supposed: not merely supplying the air that we breathe but somehow dealing with our most dangerous pollutant. But this is an idle thought: there is no evidence; a lot of research still needs to be done.

  And yet all this concerns a being we were entirely unaware of twenty years after man first went to the moon. Those who have long claimed the sea to be far less known than outer space seem suddenly to have a special brand of wisdom.

  • • •

  The great forces that created the Atlantic in the first place will in time—in a very long time, in human terms—also destroy it. The forces, part of the tectonic mechanisms of the planet, are better understood today than when they were first revealed in the 1960s, but they still present something of a mystery. They are difficult to appreciate in part because they are so complex, but also because of the time scale involved: we are around to witness only the tiny incremental movements and shifts by which the world changes its topography, even though those tiny shifts can often be, for mankind, catastrophically lethal and terrifying.

  The earthquakes, eruptions, and tsunamis that have shaken the world during the two thousand years mankind has been able to chronicle them have seemed like gargantuan affairs—death and destruction on what for humans is a titanic scale have been rained down by events that are now a familiar part of history: Lisbon 1755, Krakatoa 1883, San Francisco 1906, Tangshan 1976, Sumatra 2004. Seen in a planetary context, events like these have barely any significance. They are tiny shape-shifts that come to assume real importance only when millions of them, over millions of years, have taken place. The Sumatran tsunami of December 26, 2004, may have killed a quarter of a million people, and may have passed into human history as one of the greatest natural disasters of all time—but it moved the sea floor south of Sumatra no more a few meters northward, and the sea south of Sumatra is many thousands of miles wide. It would take a million years’ worth of submarine Indian Ocean earthquakes before this corner of the world would appear to have changed its appearance even minimally.

  It is a fortuitous accident of tectonics that the Atlantic is seismically the least vulnerable of the oceans. The Indian Ocean is scarred by subduction zones and faults, and it was no surprise to the geological community that the 2004 tsunami originated there. The Pacific is almost entirely surrounded by volcanoes and is rocked by ceaseless earthquaking from Japan to Alaska, from California to Chile, from Kamchatka to New Zealand. But the Atlantic, by contrast, has as its geological centerpiece only the Mid-Atlantic Ridge, which is certainly opening up and disgorging lava all the while—but does so in a somewhat lethargic, somnolent manner, and by the standards of the neighbor ocean can hardly be called seismically violent. When Anak Krakatoa was born off the coast of Java in 1930 it appeared with terrible violence and drama; when Surtsey was born off the coast of Iceland thirty-three years afterward it proved spectacular to see but was more a boisterous oozing than a calamitous detonation.

  That is not to say there has been an absence of memorable activity in the Atlantic. Much has happened, and the recent occurrences faithfully and fully recorded, more so than elsewhere because sophisticated, organized, scientifically curious, and technologically able man has been living on the shores of the Atlantic for very much longer than around the other oceans.91 There are many early records of violent seismic activity in the eastern Atlantic between Portugal and the Azores, for instance, beginning with a record of flooding in the Tagus in the winter of 1531, and huge waves in the sea nearby that wrecked scores of ill-prepared fishing boats and sailing vessels. Then there was the enormous earthquake that all but destroyed Lisbon on November 1, 1755: it is said to have sent massive sea waves to Madeira and Agadir, as one might expect, but also to have caused destruction as far away as Martinique, in the Caribbean.

  The question of whether destructive tsunamis are likely to travel across the Atlantic has prompted some recent concern, ever since the Indian Ocean wave of 2004, which spread rapidly and killed many, from Bengal to Sri Lanka and beyond. The records show few credible accounts of long-distance tsunamis being generated in the Atlantic—the Lisbon event is probably the only one. The Grand Banks earthquake of November 1929, triggered by a magnitude 7.2 earthquake south of Newfoundland, has been studied in great detail—great waves of sand and water, known as turbidity currents, swept down the undersea canyons and severed many of the submarine telegraph cables, the precise thirteen-hour sequence of their failures being recorded by the sudden loss of signal—but it seems not to have created much seismic excitement beyond the St. Lawrence Estuary. Similarly, the immense explosion in Halifax harbor in December 1917, mentioned in chapter 4, did transmit a number of rolling tsunamis—but they lasted only a few minutes and never made it into the open ocean.

  A three-hundred-mile long sand deposit running along the east coast of Scotland, between Dunbar and Inverness, is thought to have resulted from a famous submarine landslide off the Norwegian coast eight thousand years ago. And all sorts of mayhem is thought to have been caused on the far side of the ocean when Lake Agassiz collapsed, but no physical tsunami evidence for it has yet been uncovered, even though researchers are hoping to find fossil sandbars on the west coast of the Labrador Sea. Until then the rather tenuous suggestion, already noted, that Black Sea farming patterns changed as a result of the meter-high rise in sea level remains the sole suggestion of transoceanic impact of the great Agassiz flood.

  The concern over the possibility that destructive superwaves might be able to cross the Atlantic has come about in part because of what happened in the Indian Ocean in 2004; but in rather larger part it has also spiked because of an item of wild speculation that appeared in the press in 2000—and which held that New York City was at risk of inundation because of an impending landslide on the island of La Palma, in the Canary Islands. News stories in some of the more excitable press—and a lengthy feature film shown by the BBC—had it that a block of basalt the size of the Isle of Man was about to fall off the western side of the Cumbre Vieja volcano, and that the American president should take immediate note lest they be caught unprepared for the devastating effects of a wave that would race westward across the ocean at five hundred miles an hour and, when it struck, would drown major American cities beneath a wall of water scores of feet high.

  It later emerged that the researchers who first informed the press and who helped with the BBC film, though based at the Unive
rsity of London, were funded by a large Chicago-based reinsurance company, Aon Benfield, which would doubtless welcome a public made skittish by the publication of reports of ever more bizarre threats—MEGA-WAVE TO ENGULF MANHATTAN!—to world serenity. The seismological community generally has poured scorn on the reports, has said that the mathematical models used were outdated and wrong, that the chances of such a landslide in La Palma were vanishingly remote, and that tsunamis have little history of traveling across the Atlantic Ocean, though admittedly for reasons unfathomed. The researchers retired to lick their wounds; the BBC issued something of a retraction; and most recently the European Space Agency said it would conduct a survey of the Cumbre Vieja volcano to ascertain its stability and presumably try to reassure the world that New York is not about to be drowned, certainly not imminently, and probably never.

  The volcanoes of the Atlantic are also generally more benign than those elsewhere. To be sure, there are vicious examples, most of them in the Caribbean. On Martinique, there is most notoriously Mont Pelée, which erupted on Ascension Day in 1902, and killed almost all the twenty-eight thousand inhabitants of the town below with its rolling clouds of red-hot ash and superheated air. A prisoner in an almost airless cell survived, and joined the Barnum & Bailey circus. Patrick Leigh Fermor wrote The Violins of Saint-Jacques, a novel imagining that the celebration ball going on when the volcano erupted was swept in its entirety into the sea, such that the orchestra, still playing gamely, can be heard to this day by fishermen sailing by overhead.

  Some others are more discommoding than catastrophic—the very geologically similar complex of the Soufrière Hills on the British colonial possession of Montserrat, for example, erupted in 1995, killing many fewer people but ruining the island capital of Plymouth and forcing its abandonment. Dust from the eruption in 2010 of Eyjafjoll in southern Iceland severely disrupted air transport all across Europe. And back in 1961, the entire population of the South Atlantic island of Tristan da Cunha—another British possession, with some 250 inhabitants—had to be evacuated to England after their volcano erupted, directly threatening the little settlement of Edinburgh-of-the-Seven-Seas.

  Fewer than three hundred people—seven families, all interrelated—live on the mid-oceanic volcanic island of Tristan da Cunha, 1,800 miles west of the South African coast. Generally the British possession is isolated and alone, the islanders always fretting that their volcano might erupt again, as it did in 1961.

  When this eruption began all the Tristanians, elderly women and babes-in-arms among them, took off in longboats to Nightingale Island, twenty miles away, and sheltered off the beach awaiting rescue—the Atlantic Ocean seemingly offering them safer asylum than the solid land on which their ancestors had chosen to settle. But two years later, once the mountain had settled itself down again, most of the islanders elected to return. They live there still, proudly offering themselves to passing ships as the most isolated inhabited island in the world. The volcano may growl and steam, the sulfurous gases may produce widespread illness, the islanders’ isolation may bring all the disadvantages of inbreeding, and the economic trials of the inhabitants may be endless and legion, but in this otherwise unvisited nook of the Atlantic, mankind clings on with limpet-like tenacity, as if to try to remind the ocean just who claims mastery.

  • • •

  Some of the islanders on Tristan, and the technicians at the weather station three hundred miles farther south, on yet another British colonial sibling, Gough Island, might have noticed something else rather unusual in recent years.

  The prevailing winds in both places—but most especially on Gough Island—are from the west. In Gough they are usually very strong: the island, which lies at just about 40 degrees, 31 minutes south, is very much in the Roaring Forties, and the westerlies here do indeed roar, without cease.

  Or at least they used to. During the last thirty years or so the climate in these latitudes has somewhat altered. The westerlies do not blow so strongly or so often, and are now not so perpetual as they still seem to be just a few score miles to the south. It is as though the Southern Ocean Super-Gyre, the climatic forcing agent that is ultimately responsible for the high wind belts around the Antarctic, and which sailors know as the Roaring Forties, the Furious Fifties, and the Shrieking Sixties, has recently shifted southward, toward the pole. The reason for this, climatologists insist, is the human-induced depletion of ozone in the atmosphere above the western Antarctic: it seems that the winds might have slipped down toward the ozone hole, as it were, to fill the gap the ozone has left behind, confirming the age-old principle of nature’s abhorrence of a vacuum.

  The effect of this southward shift of the Atlantic winds has been most unexpected: it has caused warm and salty water to dribble out into the Atlantic Ocean from the Indian Ocean, through some hitherto unknown deep-sea phenomenon known as the Agulhas Leakage. This warm and saline seawater seemingly enters the North Brazil Current—an exceptionally complicated northbound current that flows along the coast of Brazil toward the Caribbean. It is believed that this water could then enter the birth waters of the Gulf Stream and change its strength, temperature, salinity, and direction even more than it is being changed today.

  Thus is a further complication—and one almost certainly initiated by mankind, if the filling-the-ozone-gap theory is correct—being added to the mix that is the Atlantic Ocean. The weather patterns around the sea will change still further—though for good or ill, no one has any current idea. All that is certain is this: with new and fiercer hurricanes forming off Cape Verde, with volcanoes erupting in Montserrat, with the sea level of Rotterdam rising and the ice in East Greenland melting, with black smokers and white smokers generating more heat and dull red light and so nurturing the clouds of thermophilic bacteria near the Mid-Atlantic Ridge, with Surtsey building itself up yet again, with Eyjafjoll erupting dustily, with Iceland still splitting apart and the cables running across the Grand Banks in danger of being broken once more, with Prochlorococcus expanding its range and burping out yet more oxygen into the air, and with, as now, Indian Ocean water leaking across into and warming and making more salty the seas near Gough Island, Brazil, and the Caribbean—with one or all of these things now happening, and with much wondering over whether humanity is able to accommodate them or whether they signal the beginning of the end of man’s relationship with this most vitally important of seas—it is clear that some exceedingly strange things are happening in today’s Atlantic Ocean, and no one is quite sure why.

  Epilogue: Falls the Shadow, Fades the Sea

  All the world’s a stage

  And all the men and women merely players:

  They have their exits . . .

  The tiny beacon they call the lighthouse at the end of the world will one day meet up with another of its kind that presently stands ten thousand miles away on the far side of the globe. And when that happens, lighthouse striking lighthouse with the slowest and gentlest of collisions, the Atlantic Ocean as we know it will cease to be.

  The final moment of the Atlantic’s existence will come in about 170 million years. It will be brought about by an episode of highly improbable-looking tectonic gymnastics, in which the tip of South America snakes itself down and around the entire continent of Antarctica, then heads back up northward and collides with the tip of the Malay Peninsula somewhere in the region of Singapore.

  A great deal of mathematical modeling had to be done to reach this vision of the world’s future appearance. Much of the calculating has been worked up by a Texas-based group that specializes in paleogeography and tectonic futurism, headed by Christopher Scotese. Another group based in England, known informally as The Future Is Wild, and with more obviously commercial ambitions, is hoping to find in Hollywood and the publishing industry a market for its carefully modeled visions of the planet’s geological and biological future. Both groups have devised scenarios for the coming couple of hundred millions of years: both agree that the supercontinent whose breakup gave rise
to the Atlantic—Pangaea—will one day re-create itself,92 and they have agreed to name it Pangaea Ultima. Precisely how the continents that currently exist get to this point is a matter for scholarly argument, but there is agreement that in the end the world will have one continent, it will be surrounded by one sea, and all of the oceans that currently exist, the Atlantic included, will have long since been consigned to history.

  However, at least at this moment the very opposite seems to be happening. The Atlantic, far from heading toward history, is getting much bigger and wider. The lines of volcanoes and rifts along the Mid-Atlantic Ridge are continuing to spew new mantle material to the surface, and the convection currents below are continuing to shift apart the seabeds on either side of the ridge, like conveyor belts moving in opposite directions: the Americas are being moved ever farther west, and Africa and Eurasia slide ponderously to the east. This is a process that all geologists believe will continue for maybe another five million years, perhaps much longer. It is after this that the mathematical models start to diverge.

  One group predicts what it calls extroversion, a process whereby the continents appear to peel open like blooming flowers, only then to shift back upon themselves and eventually coalesce into one. In this scenario, the Atlantic continues to open ever wider; the Pacific is slowly squeezed closed as the two American continents pivot around Siberia toward a collision with East Asia; and Africa, India, and Antarctica move as one around and up toward South Asia’s various peninsulas and islands; until Pangaea Ultima is finally made, and for the time being the world halts in its tracks, with its gigantic new landmass surrounded by an even more gigantic, newly shaped sea.