Che lezione trarre da eventi atmosferici estremi sempre più devastanti che colpiscono così di frequente la “città dell’uomo”?
Per molti la risposta è scontata: sono le avvisaglie del “riscaldamento globale”. Corriamo ai ripari!
Greg Ip propone un’ipotesi alternativa nel suo saggio “Unnatural Disaster: The High Cost of Taming Mother Nature”.
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Quando la tempesta “Sandy” si è abbattuta su New York, i giornali commentavano all’incirca così…
… “Our climate is changing [which] should compel all elected leaders to take immediate action.” Bloomberg acknowledged that Sandy could not be definitively pinned on global warming, but he seemed pretty convinced of a connection, as was the public: two-thirds of voters linked Sandy to climate change…
Tra uragani e politica c’è sempre stata un’attrazione fatale.
E la scienza sembra favorire il flirt…
… Science is relatively unequivocal that climate change should intensify hurricanes…
Ma il riscaldamento globale non spiega la distruzione causata da “Sandy”, che nemmeno merita il nome di “uragano”.
Le ragioni stanno altrove…
… The principal reason for Sandy’s devastating impact is that millions of productive, affluent people live and work in a place that is inherently dangerous…
Nicholas Coch, un geologo alla “City University of New York’s Queens College”, è forse il massimo esperto in materia di tempeste sulla east coast…
… The first he could find hit in 1635 but left barely a trace, striking mostly Indian villages and uninhabited forest. More impressive was the Midnight Storm, a Category 2 storm that struck in August 1893 and, as Coch later documented, literally wiped a community off the map. Hog Island, a barrier island close to what is now JFK airport that hosted pleasure seekers and swimmers during the summer, was pushed beneath the sea and largely forgotten by New Yorkers until Coch rediscovered it. The Midnight Storm paled in comparison to the Category 3 Great New England Hurricane of 1938, at the time one of the most destructive storms in American history. Nicknamed the Long Island Express, it carved out ten new inlets between Fire Island and East Hampton, lashed New York City, and destroyed or inundated towns throughout Rhode Island and Connecticut. Yet even that storm did “just” $5 billion worth of damage (in 2014 dollars)…
Nonostante i pericoli, l’insediamento umano nella zona è talmente ipertrofico che una tempesta di categoria 2 produce i danni tipici di una tempesta di categoria 4. Potremmo definire la regione di NY in questi termini…
… the most developed and populated hurricane-prone…
Queste semplici osservazioni ci chiariscono le idee…
… the main reason Sandy was so much more costly than its predecessors is that in the years since 1938, the New York region became significantly more populated… Global investment banks have built towering high-tech headquarters throughout Manhattan…
La gente nemmeno sa del pericolo che corre stando lì, si sente sicura.
La prossima tempesta farà ancora più danni proprio perché la sicurezza è stata migliorata e la gente si sentirà ancora più garantita. Il parere degli esperti…
… To those academics and risk experts who study natural disasters, neither Sandy nor its price tag was especially surprising. Just four years earlier a team led by Roger Pielke, Jr., a political scientist, calculated that another storm just like the Long Island Express would inflict $39 billion worth of damage. Karen Clark, a prominent catastrophe modeling expert, predicted damages of up to $100 billion. Importantly, this price tag didn’t require that the storm be as intense as Katrina (a Category 5, the most powerful, when it was in the Gulf of Mexico). Sandy is an example of a phenomenon routinely ignored in the barrage of news coverage of hurricanes, floods, wildfires, and other natural disasters…
Il riscaldamento globale c’entra molto poco in queste dinamiche. Magari domani giocherà un ruolo anche lui ma per ora non è un fattore critico. Bisogna guardare altrove per isolare le vere cause di tanta distruttività…
… main reason they are getting more destructive is because much more economic wealth stands in their way…
Quando l’uragano colpisce il giorno dopo la figura dell’ “Ingegnere” assurge a eroe nazionale: tutte le orecchie (a cominciare da quelle dei politici) sono per lui…
… their success at protecting us from nature with ever more elaborate defenses often means that the destruction will be that much more devastating when those defenses fail…
Ma le sue elaborate difese sono la premessa dei disastri futuri, quando colpiranno uragani più potenti degli ultimi.
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Roger Pielke e Chris Landsea si incontrarono quasi per caso al National Center for Atmospheric Research presso Boulder, in Colorado. Entrambi studiavano gli uragani, ma con conclusioni antitetiche…
… Landsea had just published a paper documenting a steady decline in the frequency of intense hurricanes in the North Atlantic; the years 1991 to 1994 were the quietest on record. Pielke, meanwhile, was doing postdoctoral research on hurricane intensity at the request of the National Science Foundation. Hurricane Andrew in 1992 had smashed all records for the most expensive hurricane in U.S. history, just a few years after Florida had been told that its worst-case scenario was two storms costing half of what Andrew ultimately did…
Il periodo di quiete (1991-1994) fu anche il periodo in cui si produssero i maggiori danni. Pielke:
… “the reason it was the most expensive period had nothing to do with it being the most active.”…
Occorreva un’impostazione alternativa per studiare il fenomeno senza incorrere in paradossi, i due si dettero da fare…
… They would study some long-ago storm, then examine how the population, wealth, and settlement patterns of the affected counties had changed since, to estimate how much damage an identical storm would cause today… Their findings were striking. The Great Miami Hurricane struck in 1926 when Miami and its surrounding county had just started to boom and the area’s population had topped one hundred thousand. Today, it is the center of a sprawling metropolitan region of more than five million, with pockets of extraordinary wealth and valuable property. Houses, condominiums, and glass-walled hotels now stand on the beaches that buffered people from the storms. The 1926 hurricane cost $1 billion (in 2011 dollars). Today, the bill would be more like $188 billion… In February 2009 the Australian state of Victoria was sweltering through an intense heat wave when a series of bushfires, probably started by downed power lines, erupted. Driven by gale-force winds, the Black Saturday fires burned across a wide front with terrifying speed, eventually destroying 2,300 homes in the northern suburbs of Melbourne and nearby towns, and killing 173 people…
Quello che accade a New York, accade ovunque nel mondo. Prendiamo Bangkok…
… Similar circumstances help explain other disasters. Bangkok has flooded so often that it was known as “the Venice of the East.” Beginning in the 1960s Thailand rapidly industrialized and became a center for automotive assembly and computer parts production for multinationals from Japan, Europe, and America. The rice paddies that lined the Chao Phraya River were drained for industrial estates that were then ringed by dikes. In 2011 heavy monsoon rains overfilled the upstream reservoirs and caused the river to flood, topping the dikes and provoking battles in Bangkok, since protecting one neighborhood by stacking sandbags or breaching dikes would simply shift the water to another area. The 2011 Thai floods became the ninth-costliest natural disaster since 1970 in terms of insured losses…
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Le diatribe sul cambiamento globale sono infuocate, anche se non tutti sanno localizzarle…
… While the vast majority of physical and social scientists agree that man-made climate change is happening (A), they are split on the best way to respond (B)…
I partiti sono due: da un lato i “mitigatori”…
… doing whatever is necessary to reduce the level of greenhouse…
… dall’altro i resilienti o “adattatori”…
… accepting that climate change is going to happen and minimize the damage…
I mitigatori non sembrano molto pazienti…
… Al Gore has compared adaptation to Nazi appeasement…
Chi non è d’accordo con loro sulla soluzione al problema B, spesso riceve l’etichetta di “negazionista”, quasi che rifiutasse la soluzione del problema A .
La triste sorte è capitata anche a Pielke jr, nonostante il pedigree dello studioso...
… his father, Roger Pielke, Sr., is a meteorologist who, back in 1984, wrote an entry for the Encyclopædia Britannica predicting that steadily rising emissions of carbon dioxide would lead to a warmer planet. As the planet warms, floods should become more destructive…
Pielke non discute del problema A…
… What he does dispute is that climate change can explain past disasters like Sandy…
Al momento il riscaldamento globale non incide sugli eventi metereologici estremi…
… number of hurricanes and droughts shows no long-term trend…
Di conseguenze bisogna cercare spiegazioni altrove.
… toll of natural disasters is going up primarily because of human development…
E guada caso le spiegazioni più ragionevoli mandano in crisi il paradigma del “mitigatore”…
… it is more practical to deal with climate change by making cities and settlements more resilient rather than simply trying to reverse the buildup of carbon dioxide in the air… storm damage, relative to GDP, isn’t rising… human behavior explains the toll of natural disasters…
Per questo e solo per questo Pielke è mal visto dai “mitigatori” e bollato a torto come “negazionista”.
Ora però resta una cosa da capire:
… why we put ourselves in harm’s way…
Perchè si fanno investimenti immobiliari a New York ben sapendo che la zona è soggetta a tempeste? Perché, insomma, si costruisce sotto l’argine di un fiume?
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Spostiamoci un po’ a sud: un buon posto per discutere la questione è il fiume Mississippi: li è da secoli che “mitigatori” e “adattatori” si scornano. Il dilemma è sempre quello: adattarsi o domare?
… The river has regularly flooded since long before Europeans settled its basin and caused the river and its delta to change shape and direction. But because it is so vital to transportation, commerce, and agriculture, Americans have been fighting to tame it…
Dal 1700 si costruiscono argini che regolarmente vengono oltrepassati dalla piena successiva. E’ una questione di probabilità, non di riscaldamento globale: prima o poi i record vengono battuti, non c’è niente da fare.
Non solo: più l’intervallo tra un disastro e l’altro si allunga, più i danni del disastro successivo sono ingenti.
Mark Twain incarna la saggezza popolare che si oppone allo sforzo pur meritorio dell’ “Ingegnere”…
… Man cannot tame that lawless stream…
E infatti…
… That’s not the way the Army Corps of Engineers saw it…
Esempio di una classica battaglia tra esperti…
… Charles Ellet, Jr., a civil engineer, linked the flood problem to the growth of settlement… and… recommended enlarged river outlets… Andrew Humphreys, an army captain, recommended building only levees… The Corps went with Humphreys’s plan…
Alla vittoria degli “Ingegneri Innalzatori di Argini” contribuì in modo decisivo un altro fattore…
… After the Civil War, the demand for civil works to accelerate the commercial and industrial development of the country led to a frenzy of federally financed levee… canals were built to protect low-lying New Orleans…
Il Governo aveva voglia di spendere. Una voglia matta.
Come sempre l’operazione fu un successo…
… Until 1927, no levee built to the standard and grade of the Mississippi River Commission had failed…
E come sempre dopo un po’ fallì…
… in 1927… massive floods burst the levees from Cairo in southern Illinois to the Gulf of Mexico, spreading out in a vast, yellow sea up to one hundred miles across. More than two hundred people died and seven hundred thousand — 80 percent of them black — lost their homes…
Grazie agli ingegneri si era potuto vivere un momento di pace: quanto più si allunga quel momento, tanto più sarà catastrofico il disastro che seguirà.
E cosa successe dopo? Niente di particolare: il ciclo riprende con forza raddoppiata…
… Edgar Jadwin… prompted Congress to make flood control an explicitly federal responsibility… marriage of engineering and economics… cost-benefit analysis…
L’analisi costi-benefici sembra il gold standard della razionalità, ma così non è: non tiene conto dei comportamenti compensativi. Non lo fa perchè sono imprevedibili e spesso annullano completamente i benefici della sicurezza.
Gilbert White, nel 1942, lui teneva in gran conto i “comportamenti compensativi” fino a formulare il cosiddetto “effetto argine”…
… White came up with what became known as the “levee effect” to describe the tendency of humanity to feel protected by levees and so build up more property in their shadows… a tendency the federal government actively reinforced…
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La gente assume che la piena non eccederà mai i massimi storici ma questo assunto è altamente improbabile. Il fenomeno “un piede in più” è la norma. Qualche esempio…
… An electrical generating station in Cincinnati was “constructed to operate at a flood stage one foot above the highest recorded flood of 1884, but in 1937 it was forced to halt operations by a crest that reached seven feet higher.”…
Altri esempi, fino a Katrina…
… In Brady, Texas, a masonry wall built to protect the business district after a 1930 flood was overtopped in 1935. The town built an earth levee three feet higher, which was overtopped in 1938. After Hurricane Betsy ravaged New Orleans in 1965, the Army Corps strengthened and expanded the region’s levees, which led to more development, which was then exposed to Katrina forty years later…
Quanto più le autorità politiche “proteggono”, tanto più si accumula ricchezza nelle zone pericolose creando le premesse per un disastro sempre più ingente. E’ un circolo vizioso…
… levee project in Dallas completed in the 1930s led to property values more than quadrupling… The self-reinforcing cycle of flood protection and development assures that natural disasters will keep growing in scale…
Una storia istruttiva (sempre la stessa): l’argine a protezione dell’aeroporto di St. Louis…
… We figured this would be high enough,” Melvin Fick, a farmer who was president of the Monarch Levee District, told the St. Louis Post-Dispatch. “It held real well in 1973 and 1986,” when record floods swelled the Missouri River. But in 1993, raging storms caused the Missouri River to crest six feet above the record reached in 1973, smashing a seven-hundred-foot-wide breach in the levee. The airport ended up under water…
Con l’aiuto federale la città è stata ricostruita e il nuovo argine alzato per ben 5 metri. Cio’ ha consentito di edificare anche uno dei centri commerciali più imponenti d’America.
Ma la teoria del “circolo vizioso” non ha insegnato niente? Al contrario, i protagonisti della ricostruzione parlano di “circolo virtuoso”…
… The designer of the protection system called it a virtuous circle, where more levees lead to more development, which leads to more levees…
Ma…
… Levees are not a fail-safe; 70 percent of the levees under stress in 1993 failed, and extreme events can always overtop them…
Ci sono poi delle esternalità: si è parlato di “guerra degli argini”…
… Chesterfield’s increased protection will raise water levels in neighboring communities in the next flood…
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I giapponesi conoscono la parola tsunami almeno dal 1600.
Noi dal 1986…
… the 1896 story “A Living God,” in which a quick-thinking village headman saves his village from being destroyed by an approaching wave. The story has helped shape Japanese thinking, reflecting the mentality that although they live in an inherently dangerous place, they can protect themselves by taking enough precautions…
La retorica dell’eroe Ingegnere veicolata dal film ha colpito anche il Giappone…
… Japanese government embarked on an extensive project of building seawalls… A third of Japan’s coast was ultimately protected… As a result, Japanese citizens felt safe living next to the water… business felt confident enough to construct the Fukushima Daiichi and Daini nuclear power plants…
L’assunto del massimo storico è stato adottato acriticamente…
… The Daiichi plant was originally designed to withstand a tsunami of up to ten feet high, because that was the size of the tsunami triggered by an earthquake off the coast of Chile in 1960… though.. much more powerful earthquakes and larger tsunamis had struck more than a thousand years earlier…
Le premesse c’erano tutte, cosicchè…
… the plants didn’t stand a chance against the powerful 2011 Tohoku earthquake… The thirty-three-foot-tall wave of black water washed through towns and swamped the seawalls protecting the power plants, disabling the low-lying diesel generators that maintained power for the reactors’ cooling systems while they were shut down…
Un esempio ancora più estremo è quello degli olandesi…
… Dutch farmers first began building dikes around land reclaimed from the North Sea to create “polders” in the twelfth century… 60 percent of the country is either below sea… In 1953, a combination of a high spring tide and a severe storm over the North Sea overwhelmed dikes, flooding 9 percent of the country’s farmland and killing eighteen hundred people…
La reazione olandese: un programma di infrastrutture per il contenimento delle acquee ancora più imponente (“Delta Works”)…
.. now… from Amsterdam to Rotterdam has been heavily industrialized and now provides most of the country’s economic output…
Esperti che si sbottonano in camera caritatis…
… Piet Dircke of Arcadis, a Dutch engineering firm… He painted a grim portrait of the outcome if the dikes were to fail… Half of Holland would be submerged… “We’d have to rebuild our complete country,”…
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Problema: come riconciliare il progresso economico con i disastri naturali?
C’è una soluzione di mercato facile facile:
… removing government subsidies for living in such places… charging insurance rates…
La lista delle politiche che incoraggiano i perversi comportamenti compensativi è lunga…
… America’s federal government spends billions building and maintaining dams, levees… The number of federal disaster declarations — which trigger federal aid equal to 75 to 100 percent of the cleanup costs — have been rising steadily…For a long time federal flood insurance plans charged people living on floodplains premiums that were lower than the true risk associated… Florida forbid insurers from charging homeowners premiums that actually reflect the risks of living there…
Basta con i sussidi e assicurazioni private: se il premio è troppo alto si trasloca altrove.
Non che il mercato sia esente da fallimenti…
… Natural barriers such as sand dunes and mangrove swamps provide protection to everybody, but those benefits aren’t easily priced or captured by private property… By contrast, the economic benefit of building mansions, condominiums, and hotels with unobstructed views of the ocean are large and readily quantified…
Ma forse tutto questo non sarebbe sufficiente: le persone non hanno una percezione di pericolo in assenza di un’esperienza personale…
… people would still choose to live in the path of floods, earthquakes… they simply don’t expect to need the protection…
Non che questo sia sempre irrazionale, in ogni caso è verosimile pensare ad una miopia del disastro naturale…
… Howard Kunreuther, a risk expert at the Wharton School, calls this “disaster myopia,” and his colleague Robert Meyer has documented a remarkable case study. In 1969, Hurricane Camille swept the Gulf Coast and slammed into the Mississippi resort town of Pass Christian. At least eight died when the Richelieu apartment complex collapsed (although they were not, as one oft-told story had it, celebrating at a hurricane party)… When I asked the mayor of Pass Christian why people would rebuild where structures and lives had been destroyed twice in the past forty-four years, he responded: “It’s not like it comes every year. There ain’t no guarantee that tomorrow we won’t have the end of the world. Should people live in California when there’s danger of an earthquake, in the east with blizzards? You tell me where the safe place is. Life is a chance. And let me tell you something else: Water sells. Water attracts more people than it will ever [scare] off.” His observation illustrates why it is so hard to break the interacting spiral between disasters and economic development…
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Sembra uno scherzo della natura: i posti più pericolosi sono anche i più belli e i più pratici…
… Rivers, coasts, and natural harbors facilitate trade and commerce… cities such as New York, Amsterdam, and London… Holland became the world’s first economic superpower because its major cities… The plate tectonics that produce earthquakes also produce natural harbors such as San Francisco’s…
Wallace J. Nichols – un biologo marino – sostiene che la vicinanza all’acqua renda l’uomo più felice.
Forse anche per questo non esiste cura contro i disastri della natura e che i danni aumenteranno. Qualche stima per il futuro…
… The World Bank estimates that between 2000 and 2050, the number of people in large cities exposed to tropical cyclones will rise from 310 million to 680 million, i.e., from 11 to 16 percent of the world’s population. Economic exposure will grow even more, because of rising sea levels, economic growth, and urbanization. In 2005, all ten of the world’s cities most economically exposed to coastal flooding were in the rich world, led by Miami, New York, New Orleans, Osaka-Kobe, and Tokyo. Those ten accounted for 5 percent of world GDP. By the 2070s, Guangzhou, Calcutta, Shanghai, Mumbai, Tianjin, Hong Kong, and Bangkok will join the list, and exposure will equal 9 percent of world GDP…
Ma perché gli uomini si stipano in grandi città costruite nei punti più pericolosi del pianeta?
Ci sono motivazioni psicologiche: essere in tanti ci dà sicurezza. Un po’ l’effetto del “tutti sulla stessa barca”, un po’ l’effetto incredulità: “non puo’ essere che tutti rischino”.
Ma ci sono anche motivazioni storiche…
… historian Lewis Mumford wrote of the origins of European cities… Five centuries of violence, paralysis, and uncertainty had created in the European heart a profound desire for security,”… “Sheer necessity led to the rediscovery of an important fact … the strength and security of a fortified stronghold, perched on some impregnable rock, could be secured even for the relatively helpless people of the lowlands provided they built a wooden palisade or a stone wall around their village.”…
E anche motivazioni razionali…
… disasters are also deadlier in the countryside… rescuers have more trouble reaching… In India, far more people in rural areas die in periods of extreme heat…
La città attira: sia i poveri che i ricchi. E’ l’ “effetto rete”…
… The economic logic that draws poor peasants to cities in India does the same for highly educated professionals in the rich world…Much of the value of cities comes from “network effects,” the increased productivity that each worker, manager, and professional derives from living, working, and interacting with others in close proximity… difficult to dislodge a city from a position of economic strength…
Le città sorgono e risorgono sempre nella stessa posizione, ci sono tristissimi esperimenti naturali…
… Allied bombing during the Second World War destroyed more than half the buildings in the sixty-six targeted cities. While the atomic bombings of Nagasaki and Hiroshima are best known, a single raid on Tokyo created an inferno that killed eighty thousand people in one night, more than Britain suffered during the entire war… most of the bombed cities had fully recovered their relative size rankings within fifteen years…
Manhattan è un buon esempio: il suo cuore è là dove sorgeva l’antico accampamento indiano…
… Compare lower Manhattan in 1609 to a present-day map and the first thing you notice is how much larger it is. Most of the buildings along the perimeter, from the World Trade Center to South Street Seaport, stand on land that has been reclaimed from the sea over the past four centuries. Not coincidentally, the areas inundated by Sandy correspond almost exactly to those parts of New York that are on reclaimed land. Thus, in some sense New Yorkers have been courting disaster virtually since the founding of the city…
Un posto pericoloso finché si vuole ma da lì non ci si sposta.
La cosa migliore da fare è rassegnarsi: rassegniamoci al futuro disastro, cerchiamo di minimizzare i danni e ripartire…
… each passing year, New York plops more precious infrastructure in the path of destruction… Jeroen Aerts and Wouter Botzen, have calculated that in the past century, the value of buildings in New York’s hundred-year flood zone has risen from less than $1 billion to $18 billion (in constant 2009 dollars)…
Bloomberg chiese a Seth Pinsky di fissare un piano in caso di tsunami su New York.
Una prima ipotesi – poi rigettata – fu quella di “scudare” la città…
… One option Pinsky’s group considered, and rejected, was to protect the entire city with gigantic, movable surge protection… That wouldn’t have been cheap: Jeroen Aerts reckons four barriers, at Arthur Kill, the Verrazano Narrows, the East River, and Jamaica Bay, would cost up to $17 billion. Nor would it have been foolproof: for one thing, the water the barriers would deflect has to go somewhere, and thus unprotected neighborhoods just outside the barriers would be even harder hit. Protecting those areas would cost another $12 billion, and even then some regions would be left unprotected…
L’opzione di liberare il territorio prospiciente al mare dagli insediamenti umani non fu neanche presa in considerazione. Anzi…
… apartment buildings have gone up near the water in Brooklyn and Queens…
Pinsky “fuori onda” ammette…
… “No matter how good our defenses are, from time to time nature is always going to overcome them… we have to make the city more resilient…”
Insomma, New York è indifendibile, inutile perdere tempo con piani astrusi, rassegniamoci al disastro e minimizziamo le perdite. Se il disastro sarà immane prepariamoci ad abbandonare per sempre il sito o a ricostruire tutto da zero in attesa del prossimo evento. Ecco le poche misure credibili…
… Thus, some neighborhoods will have beaches and sand dunes replenished to create natural storm-surge barriers, while buildings will be reinforced to withstand floodwater and their electrical and mechanical systems will be moved from the basement to an upper floor. Increased bus and bicycle right-of-ways will be implemented when the subways are flooded. Cities everywhere are coming to the same conclusion: rather than build ever higher defenses against inevitable flooding, they are finding ways to let the water in with as little damage as possible…
La messa in sicurezza delle città non sembra certo in cima ai pensieri degli uomini…
… The frenzy of real estate development in Miami might seem crazy given the city’s vulnerability to a rising sea level…
Per Robert Meyer un simile stato di cose è razionale: puntiamo ad arricchirci e la ricchezza ci consentirà di rispondere meglio al disastro. La prevenzione di certo impoverisce e molto probabilmente fallisce.
La città ricca è un magnete. Facciamo ancora il caso di New York…
… If you had predicted in 2000 that New York would, in the coming twelve years, suffer a terrorist attack that killed three thousand and brought down its tallest skyscrapers, a financial crisis that toppled some of Wall Street’s most powerful firms, and then a hurricane that put huge sections of the city under water, what would you have predicted would happen to the city’s population? Probably not that it would grow by 5 percent, or nearly four hundred thousand people…
Il prevedibile destino della grande mela racconta una storia universale:
… Someday, New York is going to be hit by another Sandy, and chances are, it will be far more costly than the last — not because the city failed, but because it succeeded at making even more people feel safe long enough to prosper…
