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The Attacking Ocean
The Past, Present, and Future of Rising Sea Levels
By Brian Fagan BLOOMSBURY PRESS
Copyright © 2013 Brian Fagan
All rights reserved.
ISBN: 978-1-60819-692-0
Excerpt
CHAPTER 1
Minus One Hundred Twenty-Two Meters and Climbing
On October 28, 2012, Hurricane Sandy, the largest Atlantic hurricane on record, came ashore in New Jersey. Sandy's assault and sea surge brought the ocean into neighborhoods and houses, inundated parking lots and tunnels, turned parks into lakes. When it was all over and the water receded, a huge swath of the Northeast American coast looked like a battered moonscape. Only Hurricane Katrina, which devastated New Orleans in 2005, was more costly. Katrina, with its gigantic sea surge, had been a wake-up call for people living on low-lying coasts, but the disaster soon receded from the public consciousness. Sandy struck in the heart of the densely populated Northeastern Corridor of the United States seven years later and impacted the lives of millions of people. The storm was an epochal demonstration of the power of an attacking ocean to destroy and kill in a world where tens of millions of people live on coastlines close to sea level. This time, people really sat up and took notice in the face of an extreme weather event of a type likely to be more commonplace in a warmer future. As this book goes to press, a serious debate about rising sea levels and the hazards they pose for humanity may have finally begun—but perhaps not.
Sandy developed out of a tropical depression south of Kingston, Jamaica, on October 22. Two days later, it passed over Jamaica, then over Cuba and Haiti, killing seventy-one people, before traversing the Bahamas. Come October 28, Sandy strengthened again, eventually making landfall about 8 kilometers southwest of Atlantic City, New Jersey, with winds of 150 kilometers an hour. By then, Sandy was not only an unusually large hurricane but also a hybrid storm. A strong Arctic air pattern to the north forced Sandy to take a sharp left into the heavy populated Northeast when normally it would have veered into the open Atlantic and dissipated there. The blend produced a super storm with a wind diameter of 1,850 kilometers, said to be the largest since 1888, when far fewer people lived along the coast and in New York. Unfortunately, the tempest also arrived at a full moon with its astronomical high tides. Sandy was only a Category 1 hurricane, but it triggered a major natural disaster partly because it descended on a densely populated seaboard where thousands of houses and other property lie within a few meters of sea level. Imagine the destruction a Category 5 storm would have wrought—something that could happen in the future.
The scale of destruction was mind-boggling. Sandy brought torrential downpours, heavy snowfall, and exceptionally high winds to an area of the eastern United States larger than Europe. Over one hundred people died in the affected states, forty of them in New York City. The storm cut off electricity for days for over 4.8 million customers in 15 states and the District of Columbia, 1,514,147 of them in New York alone. Most destructive of all, a powerful, record-breaking 4.26-meter sea surge swept into New York Harbor on the evening of October 29. The rising waters inundated streets, tunnels, and subways in Lower Manhattan, Staten Island, and elsewhere. Fires caused by electrical explosions and downed power wires destroyed homes and businesses, over one hundred residences in the Breezy Point area of Queens alone. Even the Ground Zero construction site was flooded. Fortunately, the authorities had advance warning. In advance of the storm, all public transit systems were shut down, ferry ser vices were suspended, and airports closed until it was safe to fly. All major bridges and tunnels into the city were closed. The New York Stock Exchange shut down for two days. Initial recovery was slow, with shortages of gasoline causing long lines. Rapid transit systems slowly restored ser vice, but the damage caused by the storm surge in lower Manhattan delayed reopening of critical links for days.
The New Jersey Shore, an iconic vacation area in the Northeast, suffered worst of all. For almost 150 years, people from hot, crowded cities have flocked to the Shore to lie on its beaches, families often going to the same place for generations. They eat ice cream and pizza, play in arcades once used by their grandparents, drink in bars, and go to church. The Shore could be a seedy place, fraught with racial tensions, and sometimes crime and violence, but there was always something for everybody, be they a wealthy resident of a mansion, a contestant in a Miss America pageant, a reality TV actor, a skinny-dipper, or a musician. Bruce Springsteen grew up along the Shore and his second album featured the song "4th of July, Asbury Park (Sandy)," an ode to a girl of that name and the Shore. "Sandy, the aurora is rising behind us; the pier lights our carnival life forever," he sang. The words have taken on new meaning since the hurricane came.
Fortunately, the residents were warned in advance of the storm. They were advised to evacuate their homes as early as October 26. Two days later, the order became mandatory. New Jersey governor Chris Christie also ordered the closure of Atlantic City's casinos, a decision that proved wise when Sandy swept ashore with brutal force, pulverizing long-established businesses, boardwalks, and homes. Atlantic City started a trend when it built its first boardwalk in 1870 to stop visitors from tracking sand into hotels. Boardwalk amusements are big business today, many of them faced by boardwalks that are as much as a 0.8-kilometer from the waves. Now many of the Shore's iconic boardwalks are history. The waves and storm surge destroyed a roller coaster in Seaside Heights; it lay half submerged in the breakers. Seaside Heights itself was evacuated because of gas leaks and other dangers. Piers and carousels vanished; bars and restaurants were reduced to rubble. Bridges to barrier islands buckled, leaving residents unable to return home. The Shore may be rebuilt, but it will never be the same. A long-lived tradition has been interrupted, perhaps never to return. For all the fervent vows that the Shore will rise again, no one knows what will come back in its place along a coastline where the ocean, not humanity, is master.
As the waters of destruction receded, they left $50 billion of damage behind them, and a sobering reminder of the hazards millions of people face along the densely populated eastern coast of the United States. Like Hurricanes Katrina in 2005 and Irene in 2011, Sandy showed us in no uncertain terms that a higher incidence of extreme weather events with their attendant sea surges threaten low-lying communities along much of the East Coast—from Rhode Island and Delaware to the Chesapeake and parts of Washington, DC, and far south along the Carolina coasts and into Florida, which escaped the full brunt of Sandy's fury. There, high winds and waves washed sand onto coastal roads and there was some coastal flooding, a warning of what would certainly occur should a major hurricane come ashore in Central or Southern Florida—and the question is not if such an event will occur, but when.
One hundred and twenty meters and climbing: that's the amount of sea level rise since the end of the Ice Age some fifteen thousand years ago. Slowly, inexorably, the ascent continues in a warming world. Today the ocean laps at millions of people's doorsteps—crouched, ready to wreak catastrophic destruction with storm-generated sea surges and floods. We face a future that we are not prepared to handle, and it's questionable just how much most of us think about it. This makes the lessons of Katrina, Irene, and Sandy, and other recent storms important to heed. Part of our understanding of the threat must come from an appreciation of the complex relationship between humanity and the rising ocean, which is why this book begins on a low land bridge between Siberia and Alaska fifteen thousand years ago ...
Between Siberia and Alaska, late summer, fifteen thousand years ago. A pitiless north wind fills the air with fine dust that masks the pale-blue sky. Patches of snow lie in the shallow river valleys that dissect the featureless landscape. A tiny group of humans trudge down the valley close to water's edge, the wind at their backs, the men's eyes constantly on the move, searching for predators. They can hear the roar of the ocean in the shallow bay, where wind squalls whip waves into a white frenzy. A few days earlier, the women had trapped some arctic ptarmigan with willow snares, but the few remaining birds hanging at their belts are barely enough for another meal. A dark shadow looms through the dusty haze—a solitary young mammoth struggling to free itself from mud at river's edge.
The men fan out and approach from downwind, scoping out the prospects for a kill. The young beast is weakening rapidly after days in the muddy swamp. Nothing is to be gained by going in for the kill at the moment, so the band pitches camp a short distance away and lights a large fire to keep away predators. A gray, bitterly cold dawn reveals the helpless mammoth barely clinging to life, mired up to its stomach. A young man leaps onto the beast's hairy back and drives his stone-tipped spear between its shoulder blades, deep into the heart. He jumps off to one side, landing in the mud. The hunters watch the mammoth's death throes and thrust more spears into their helpless prey. Soon everyone moves in to skin the flanks and dismember the exposed parts. A short distance away, wolves lurk, ready to move in when the humans leave.
Back in camp, the men build low racks of fresh mammoth bone and lay out strips of flesh to dry in the ceaseless wind, while the women and children cook meat over the fire. Around them, the dust-filled gloom never lifts, the wind blows, and the roar of the ocean never leaves their consciousness. The sea is never a threat, for their lives revolve around the land and they can easily avoid any encroaching waves by doing what they always have done—keeping on the move.
This imagined mammoth hunt unfolded at a time when the world was emerging from a prolonged deep freeze. The bitter cold of a long glacial cycle had peaked about seven thousand years earlier, the most recent of a more than 750,000-year seesaw of lengthy cold and shorter interglacial periods driven by changes in the earth's orbit around the sun, which had began 2.5 million years ago. Twenty-one thousand years ago, world sea levels were just under 122 meters below modern shorelines. The seas were beginning to rise fast, as a rapid thaw began and glacial meltwater flowed into northern oceans. Soon one would need a skin boat to cross from Siberia to Alaska and the mammoth hunters' killing grounds would be no more.
An ascent of 122 meters is a long way for oceans to climb, but climb it they did, most of it with breathtaking rapidity by geological standards, between about fifteen thousand years ago and 6000 B.C.E. Most of the ascent resulted from powerful meltwater pulses that emptied enormous quantities of freshwater from ice sheets on land into northern waters and around Antarctica. This was not, of course, the first time that such a dramatic rise had transformed an ice-bound world, but there was an important difference fifteen millennia ago. For the first time, significant numbers of human beings, perhaps as many as hundreds of thousands of them, lived in close proximity to the ocean.
Some traveled offshore. Fifty thousand years ago, even while the late Ice Age was at its height, small numbers of Southeast Asians had already ventured into open tropical waters to what are now Australia and New Guinea. Well before twenty thousand years ago, people were living on the islands of the Bismarck Strait in the southwestern Pacific. These voyages took place long before melting ice sheets and rising sea levels transformed the Ice Age world of Homo sapiens.
We live in a rapidly warming world, where human activities now play a significant part in long-term climate change and have done so since the Industrial Revolution, when fossil fuels like coal came into widespread use. It's hard for us to imagine just how different the world was twenty-one thousand years ago. Much of it lay under thick ice. Two huge ice sheets covered virtually all of North America, from the Atlantic to the Pacific. The Cordilleran ice sheet, centered on the Rockies and western coastal ranges, mantled 2.5 million square kilometers. The enormous Laurentide ice sheet lapped the Cordilleran in the west and covered over 13 million square kilometers of what is now Canada. It was nearly 3,353 meters thick over Hudson Bay. Its southern extremities covered the Great Lakes and penetrated deep into today's United States. The Greenland ice sheet was 30 percent larger than today. Another smaller ice sheet linked it to the northern margins of the Laurentide.
In northern Europe, the Scandinavian ice sheet extended from Norway to the Ural Mountains over an area of 6.6 million square kilometers, may even have reached Spitsbergen, and flowed over much of the north German Plain. A smaller ice sheet covered about 340,000 square kilometers and reached halfway down the British Isles. Glaciers descended close to sea level in the Southern Alps. In Siberia and Northeast Asia, ice extended over at least ten times the area of the British ice sheet. Extensive ice sheets mantled the Himalayas.
The Antarctic ice sheet was about 10 percent larger; seasonal sea ice extended eight hundred kilometers out from the continent. There were important ice sheets on the Andes Mountains, in South Africa, southern Australia, and New Zealand. Twenty-one thousand years ago, there was two and a half times as much ice on land as there is today. Of that, 35 percent was on North America, 32 percent on Antarctica, and 5 percent on Greenland. Today, 86 percent of the world's continental ice is on Antarctica, 11.5 percent on Greenland.
There was so much water locked up in glacial ice sheets and sucked out of the oceans that global sea levels were up to 122 meters below those of today. These much lower sea levels changed the shape of entire continents. Perhaps most significant historically was the bitterly cold and low-lying Bering Land Bridge that linked Siberia and Alaska, a natural highway that brought the first humans to the Americas. Dry land joined islands in Southeast Alaska and the Pacific Northwest of North America. Much farther south, San Francisco's Golden Gate channel was a narrow tidal gorge with fast-moving rapids. Continental shelves extended some distance off the Southern California coast, leaving but eleven kilometers of open water between the mainland and the Channel Islands close offshore.
On the other side of the Pacific, low sea levels joined the Japanese islands to Sakhalin Island in the north and brought them much closer to the Chinese and Korean mainland. In China, major rivers like the Huang He in the north and the Yangtze in the south flowed through incised, narrow valleys rather than broad floodplains. Rolling plains stretched far into the distance off Southeast Asia. Only short stretches of open water separated the mainland from Australia and New Guinea, which were a single landmass, now covered by the shallow Arafura Sea.
The configuration of the Indian Ocean was much different from today. Bangladesh lay far above sea level by modern standards, incised by the Ganges and other rivers that flowed much more rapidly to the sea. Sri Lanka's twenty-nine-kilometer-long Rama's Bridge, now a chain of limestone shoals, was a land bridge to India. The Persian Gulf was dry land, an arid landscape bisected by a narrow gorge that drained the highlands and plains at its head.
Had one looked down from a satellite at Europe and the Mediterranean eighteen thousand years ago, one would have surveyed unfamiliar landscapes. Continental shelves extended far into the Bay of Biscay. You could walk from Britain to France, had you possessed a canoe to carry you across an enormous estuary that carried the waters of the Rhine, Seine, and Thames Rivers of today. The southern North Sea was a land of shallow lakes and marshes. The Mediterranean was far smaller, its narrow entrance at the Strait of Gibraltar scoured by fast-running currents. The northern Aegean Sea ended in a high barrier that isolated what is now the Black Sea from the ocean. The Euxine Lake, formed by glacial and freshwater runoff from the north, lay behind the natural berm. On the other side of the Mediterranean, the arid Nile delta with its sand dunes extended far into what is now open sea.
Everywhere large rivers like the Thames and the Rhine had lower courses and estuaries far different from those of today. The Nile flowed through a twisting, narrow gorge, where the annual flood for the most part remained close to the river channel rather than spilling over a wide floodplain as it did until the building of the Aswan Dam. In the Americas, the St. Lawrence River did not exist; it was under the Laurentide ice sheet. The Mississippi and Amazon Rivers cut far below their modern gradients, with almost none of the ponding and wetland formation that developed as sea levels rose.
Rapid, natural global warming transformed the late Ice Age world into what was effectively an entirely different place in less than ten thousand years. Within this brief time frame, the world's sea levels rose 122 meters.
Eustacy and isostasy: the words used to describe sea level changes glide easily off the tongue, but they mask very complex and still only partially understood geological processes. What does cause the world's sea levels to rise and fall? Isostatic changes result from local upward and downward shifts in the lithosphere, the uppermost layers of the earth. Such factors as earthquake activity and shifts of tectonic plates far below the earth's surface are important contributors to sea level change. Subsidence in river deltas, changes in glaciers, even sediment compaction—anything that adds to or subtracts from the weight of the earth's crust—all can cause isostatic sea level rises, such as are common in places like Shanghai.
Eustatic, global sea level rise is completely different, a mea sure of the increase in the volume of water in the oceans expressed as a change in water height. Everyone knows that water expands as it heats. When the earth's atmosphere warms, the ocean absorbs much of the increasing heat and its waters swell. Thermal expansion is the major cause of global sea level rise since the 1860s, when the Industrial Revolution with its promiscuous use of fossil fuels added more carbon and other pollutants to the atmosphere—in other words, when humanly caused global warming began. At present, eustatic sea level rise advances at a rate of about two millimeters a year if calculated on an average of the past century. Over the past fifteen years, however, the averaged rate is around three millimeters a year, apparently a direct, accelerated response to global warming.
(Continues...)
Excerpted from The Attacking Ocean by Brian Fagan. Copyright © 2013 by Brian Fagan. Excerpted by permission of BLOOMSBURY PRESS.
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