In devastated New Orleans, ninety miles to the west, we saw a similar abandonment of entire neighborhoods. There were blocks and blocks of leaning houses, trashed and dark except for the colorful graffiti of rescue-worker symbols. The hieroglyphs recorded each house’s history in spray paint—the date searched, any noted hazards, whether any human bodies had been found. Living in one home was a pack of feral dogs.
So that is why, while standing on a gorgeous sunny beach, I was thinking about glaciers. In smashing my uncle’s former home, Hurricane Katrina had made the dry statistics of my field feel real—on a personal, visceral level. Although glacial melt hadn’t caused Katrina, I was thinking about the indelible control the world’s ice holds over our coastlines. When the glaciers grow, oceans fall. When they shrink, oceans rise. Oceans and ice have danced in this way, embraced in lockstep, for hundreds of millions of years. From my geophysical training I knew this. From my own research and that of colleagues, I knew how quickly the world’s glaciers were retreating. And for miles inland behind me, and hundreds of miles along the coast in either direction, the ground on which I stood lay barely above the surf. I had understood all this before in abstraction, but this endless plain of destruction made it real.
Global sea levels are now steadily rising nearly one-third of a centimeter every year, driven by melting glacier ice and the thermal expansion of ocean water as it warms.258 There is absolutely no doubt about this. There is absolutely no doubt that it will continue rising for at least several centuries, and probably longer. Sea-level rise really is happening. The big unknowns are how fast, whether it will progress smoothly or in jerks, and how high the water will ultimately go.
We shall explore the scary possibilities of fast sea-level rise in Chapter 9; for now, let’s stick to conservative models and what has been measured thus far. In the 1940s, global average sea level was about ten centimeters lower than today, but was rising more than 1 millimeter per year (a brisk rate at the time). It is currently rising 2-3 millimeters per year, and that number is projected to grow by around 0.35 millimeters for each additional degree Celsius of climate warming.259
Depending on whose model you like, this means we are looking at around 0.2-0.4 meters of sea level rise by 2050, or calf-deep. The state of California has just begun damage assessment and planning for 0.5 meters by that time,259,260 around knee-deep. And 2050 is just the beginning. By century’s end, global sea level could potentially rise from 0.8 to 2.0 meters.261 That’s a lot of water—up to the head of an average adult. Much of Miami would be either behind tall dikes or abandoned. Coastlines from the Gulf Coast to Massachusetts would migrate inland. Roughly a quarter of the entire country of Bangladesh would be underwater.
When oceans rise, all coastal settlements face challenges. Higher sea levels expand the inland reach and statistical probability of storm surges like the one Hurricane Katrina blew into the Gulf Coast. Decidedly unhelpful is a two-in-three chance that climate warming will make typhoons and hurricanes more intense than today, with higher wind speeds and heavier downpours.262 And just as we saw for water supply, there are other, nonclimatic actors that make the problem even worse. In fact, all four of our global forces are conspiring to place some of the world’s most important cities at risk.
Most of the world’s largest and fastest-growing urban agglomerations—like Mumbai, Shanghai, and Los Angeles—are globalized port cities on the coasts. Their populations and economies are rising fast. Demographers and economic models tell us they will grow even more over the next forty years.
Particularly in Asia, many of these great cities are located on “megadeltas,” enormous flat protrusions of mud and silt that grow where large rivers drop off their carried sediment upon entering and dissipating into the ocean. These piles of sediment are ferociously attacked by the ocean’s waves and storm surges, but the rivers keep dumping more. Like giant conveyer belts of cement, they keep trundling material to the river mouths—often from thousands of miles inland—to overwhelm the ocean’s defenses. Over centuries to millennia, the rivers grow the land out.
These deltas have always attracted humans. Farmers love their thick, rich soils that are also flat, well-watered, and have few rocks. Ships can ply both oceans and continental interiors. The river brings in freshwater for towns and cities, then carries their wastes off to the sea. A delta’s flat terrain is appealing to build on; the surrounding swamps and forests are teeming with fish and wildlife.
The problem, of course, is that the very existence of deltas is maintained by the constant sedimentation from flooding and back-and-forth migration of their rivers. They are full of low-lying swales that inundate readily. As human settlements grow, there is increasing pressure to expand into these dangerous areas. This happens not only with deltas but urbanizing river floodplains as well, like Cedar Rapids in Iowa. Flood damages therefore rise as development pushes into low-lying swamps considered too dangerous before. The reason Katrina spared New Orleans’ historic French Quarter is that it was the first place to be colonized: Even in 1718 people knew to perch their houses on that crescent-shaped sliver of natural levee, piled a few feet higher than the nearby swamps where the Upper Ninth Ward would drown nearly two centuries later.
As delta cities grow and their rivers become oversubscribed or polluted, they start pumping their groundwater resources. Groundwater removal—from what is essentially a pile of wet mud—causes the delta sediments to compact and settle, lowering the delta’s elevation closer to that of the sea. Even in the absence of groundwater pumping, some settling is normal. In a natural system, this settling is compensated by fresh blankets of silt laid down by floods. But the dikes and levees built to protect delta cities also prevent these fresh reinforcements from arriving. Farther upstream, dams thrown across the river snare the delta’s lifeblood of new sediment. Dam operators groan and search their budgets for dredging money. The conveyor belt is cut. Hundreds of miles downstream, the ocean starts taking back the land.
Important delta cities are found all over the world. They face the triple threat of rising oceans, sinking land, and sediment-starved coastlines. Without replenishment their coasts are washing away, bringing ocean wave energy and storm surges ever closer to the sinking cities. When combined with projected trends of rising sea level, population, and economic power, this puts some of the world’s most populous and prosperous places in harm’s way.
The risk assessment study on the next page was recently commissioned by the OECD.263 The study considered all 136 of the world’s major port cities holding one million people or more. As of 2005, about forty million people living in these cities were considered to be living in places at direct risk from flooding. The total economic exposure to flooding—in the form of buildings, utilities, transportation infrastructure, and other long-lived assets—was about USD $3 trillion, or 5% of global GDP.264 Under current trajectories of population growth, economic growth, groundwater extraction, and climate change, by the 2070s the total exposed population is forecast to grow more than threefold, to 150 million people. The economic exposure is forecast to rise more than tenfold, to USD $35 trillion, or 9% of global GDP. Of the top twenty major at-risk cities, exposed human populations could rise 1.2- to 13-fold, and exposed economic assets 4- to 65-fold, by the 2070s. Three-quarters of these major cities—nearly all of them in Asia—are found on deltas. Clearly, we are about to begin paying great attention to a new kind of defense spending. It’s called coastal defense.
Top Twenty World Port Cities Most Vulnerable to global Sea Level Rise, Hurricanes, and Land Subsidence
(Sources: R.J. Nicholls, OECD, 2008)
Imagining 2050
The trends I’ve described—rising water demand; oversubscribed and/or polluted water sources; reduced time-delays and free storage from snow and ice; sharper floods and droughts that are also harder to predict and insure against; the competitive marriage of water to energy; and booming port cities on increasingly risky coasts—all stem from our four global forces of d
emographics, natural resource demand, globalization, and climate change.
Whether for-profit multinational corporations offer the best solution for tackling water quality problems in impoverished countries remains an open question that is heatedly debated. However, global trade flows of “virtual water” embedded in food, energy, and other goods are already smoothing out some stark water inequities around the world. Compared with other irritants, international water disputes have seldom led to war. Continued economic integration could foment even better water management across borders—especially when nudged along by free hydrologic data measured from space and posted openly on the Internet. Finally, the not-so-far-fetched possibility that new international trade flows in water—not just virtual but actual, physical water—could emerge as a partial solution for some water-stressed places that will be explored further in Chapter 9.
Looking ahead to the next forty years, it’s not hard to see where the big pressure points lie. Joseph Alcamo directs a research institute at the University of Kassel dedicated to exploring different possible futures for humanity’s water supply. To do this they built WaterGAP,265 a sophisticated computer model incorporating not only climate change and population projections but also other factors like income, electricity production, water-use efficiency, and others. WaterGAP is thus a powerful tool for simulating a range of possible outcomes depending on the choices we make.
A typical, “middle-of-the road” WaterGAP scenario is shown here for 2050.266 Regardless of how the WaterGAP model parameters are twiddled, the big picture is clear: The areas where human populations will be most water-stressed are the same areas where they are water-stressed now, but worse. From this model and others, we see that by midcentury the Mediterranean, southwestern North America, north and south Africa, the Middle East, central Asia and India, northern China, Australia, Chile, and eastern Brazil will be facing even tougher water-supply challenges than they do today. One model even projects the eventual disappearance of the Jordan River and the Fertile Crescent267—the slow, convulsing death of agriculture in the very cradle of its birth.
Computer models like these aren’t built and run in a vacuum. They are built and tuned using whatever real-world data scientists can get their hands on. Take, for example, the western United States. In Kansas, falling water tables from groundwater mining is already drying up the streams that refill four federal reservoirs; another in Oklahoma is now bone-dry. These past observed trends, together with reasonable expectations of climate change, suggest that over half of the region’s surface water supply will be gone by 2050.268 Kevin Mulligan’s projection of the remaining life of the southern Ogallala Aquifer requires no climate models at all—it simply subtracts how much water we are currently pumping from what’s left in the ground, then counts down the remaining years until the water is gone.
In the United States, the gravest threat of all is to the Colorado River system, the aorta of water and hydropower for twenty-seven million users in seven states and Mexico. It supplies the cities of Los Angeles, Las Vegas, Tucson, and Phoenix. It irrigates over three million acres of highly productive farmland. Global climate models almost unanimously project that human-induced climate change will reduce Colorado River flows by 10%-30%269 and already, its water is heavily oversubscribed.
More water is legally promised to the Colorado’s various shareholders than actually flows in the river.270 Its left and right ventricles are Lake Mead and Lake Powell, two enormous reservoirs created by the Hoover and Glen Canyon dams, respectively. They haven’t been full since 1999. A bitter combination of high demand, high evaporation, and falling river flows has thrown the Colorado River system into a massive net deficit of nearly one million acre-feet per year, enough water for eight million people. By 2005, Lake Powell was two-thirds empty and almost to “dead pool” (the elevation of its lowest outlet, below which no water can be released by the dam and it ceases to function).271 This desiccation stranded marinas and boat docks on dry land and left a white bathtub ring some ten stories high on Lake Powell’s newly exposed canyon walls. “It was as though in four years . . . Lake Powell had simply vanished,” wrote James Lawrence Powell of his namesake in Dead Pool.
I’m glad humanity has a decent track record with things like settling water disputes with courts rather than missiles, and exporting food from the places that have water to the places that don’t: If any of these model forecasts are correct, we’re going to need it. Humans currently withdraw about 3.8 trillion cubic meters of water annually, and are projected to require more than six trillion in the next fifty years. To serve India’s expected 2050 population of 1.6 billion, even with improved water efficiency, will require a near-tripling of its water supply. Farmers, energy utilities, and municipalities are all in competition for water. Put it all together and the numbers don’t add up. Something will have to give.
The survival of California’s thirsty dry cities—like Los Angeles and San Diego—seems all but guaranteed. Their populations and economies are growing briskly. Despite annual sales of over USD $30 billion, California agriculture still contributes less than 3% to the state’s economy—and cities use far less water than irrigated farms. Even with climate changes and a projected 2050 population of about 20 million, there will still be ample water for Angelenos and San Diegans to drink and shower and cook. Ample water for California farmers, however, is far less assured.
Forced to choose, cities will trump agriculture. Farmers will either lose or sell their historic water rights. Croplands will return to desert. The first signs of an urban takeover have already begun: After years of lawsuits, farmers of California’s Imperial Valley were forced to sell two hundred thousand acre-feet of their yearly Colorado River water allocation to San Diego in 2003. That fallowed twenty thousand acres of farmland. By early 2009 the Metropolitan Water District—supplier of twenty-six cities throughout Southern California—was trying to buy seven hundred thousand acre-feet more.272
Cities versus farmers: the real Water Wars.
PART TWO
THE PULL
CHAPTER 5
Two Weddings and a Computer Model
My adoptive groomsman, whom I’d just met the night before, cracked open the church door and peeked anxiously out at the parking lot. It was a sorry mess of black asphalt, lingering slush, and streaming water. Some early guests were sitting in their cars, peering through their headlights for a dry way into the church. It was early afternoon but very dark. I’d expected dim—we were, after all, just three hundred miles shy of the Arctic Circle in the middle of winter—but not this. The expected reflective blanket of fluffy white snow was gone. My dress socks were wet and cold. We’d strategically timed our wedding day for the prettiest, whitest, most winter-wonderland month of the year. But instead, in the middle of February, some five hours north of Helsinki, a thousand miles northeast of London, and almost twenty degrees of latitude north of Toronto—there was only a steady downpour of rain.
More precisely it was our first wedding day, taking place across the Atlantic for my new European family and friends. Our second wedding day—for American families and friends—was a month later in the sunny desert resort of Palm Springs, California. Mid-March is peak tourist season in Palm Springs, with infallible blue skies and flawless temperatures hovering in the 70s. We had booked all outdoor venues for the day’s events. Our tremulous queries about tents and patio heaters—just in case of a weird-weather repeat—were politely but firmly dismissed. The weather here is always perfect in March, we were told. That’s why people pay twice as much to come then.
You know what happened next. A line of fat squalls sprayed cold rain onto our guests’ unprotected heads. By the time the lasagna came out, the temperature had plunged fifteen degrees. We did manage to scrounge up four patio heaters somehow, around which the jacketless masses could huddle. We were shocked and upset—again—by freaky weather. But just like our sub-Arctic celebration, the crowd’s good spirits soon prevailed. Both ceremonies went on as plan
ned. Cakes were cut, dances were danced, and good times were had by all.
I shouldn’t have been so surprised. While there will always be some weird weather happening somewhere, my wedding experiences were consistent with everything we know about the statistics of climate change. I had described such phenomena many times (though as probabilities, not specific occurrences) to thousands of students in my lectures at UCLA. From my research and travels to the NORCs, plenty of people had told me about bizarre rains in the depths of winter. After a while I’d even become bored with it—one can only listen to so many bizarre-weather stories before it just isn’t new information anymore.
In the previous chapter, we explored how the statistical norms of flood and drought frequency are changing, and how they might become more intense in the future. Now it is time to discuss rising air temperatures in the North—even in the dead of winter and at very high latitudes. Indeed, this phenomenon is a central interest throughout the rest of this book.
Four facts about global climate change need to be made very clear.
The first is that any process of climate change—both natural and man-made—unfolds erratically over time. In fact, its behavior is not unlike that of the stock market.
As every investor knows, long-term trends in the stock market are overprinted with short-term fluctuations. We don’t normally assume that share prices will move smoothly up or smoothly down. Instead, and usually within days, we expect they will reverse, before reversing again, and so on. Wise investors accept this short-term volatility as being largely unpredictable, yet bank on the existence of an underlying long-term trend to guide their overarching portfolio strategy. They say that while short-term markets react to unpredictable things like profit-taking, news reports, and God-knows-what, a long-term trend is more fundamental. And indeed, they are right. Throughout modernity the long-term trend has been for stock values to rise. Its underlying driver is growth of the real economy, fueled by the steady rise of human population and prosperity.
The World in 2050: Four Forces Shaping Civilization's Northern Future Page 14