J.R. McNeill
Georgetown University

Natural shocks regularly took a demographic toll. A sense of the upper limits of these tolls is available from Table 1, above. But it is worth emphasising that the great majority of floods, drought, epidemics, etc. had only local or regional effects, and killed small numbers of people.

This was true in the distant past because human population was small. It has been true in the past 50 years partly because of luck (nothing really bad has come up since the influenza pandemic of 1918-19) and partly because public health systems, disaster management systems and so forth have grown remarkably (albeit imperfectly) effective. Probably the worst era, in terms of demographic losses from natural shocks, came between AD 1300 and 1920.

Interestingly, heightened mortality was not the only source of demographic decline connected to natural shocks. When their expectations for the future were lowered, their faith shaken, young people tended to postpone marriage, either of their own will or because their elders required it. Moreover, married people, in such dark times, found ways to restrict their fertility.

Consequently, for the duration of most disasters, and in the wake of those that were specially disheartening, not only did more people than usual die, but fewer than usual were born. Wars and economic depressions produced this effect too. Its magnitude varied tremendously, with the degree of discouragement and the availability of knowledge and means to prevent conceptions.

Normally, if disaster was followed by good fortunes, exuberant fertility made up for the losses within a few years. In some cases, however, reproduction slowdowns and strikes lasted decades. This appears to have been the case with the native populations of the Americas during and after the relentless epidemics of the 16th and 17th centuries.

The economic effects of natural shocks, unlike the demographic ones, have tended to grow and grow. But that is mainly for other reasons: the world economy is now so large that there is much more at risk. Global GNP grew 15-fold in the 20th century, and more than 4-fold in per capita terms.16 The direct effects of damage to property depended on where disasters occurred. None were worse, in monetary terms, than the Kobe earthquake of 1995, whose costs may have topped $200 billion, and 2005’s Hurricane Katrina, whose costs are put variously between $25 billion and $100 billion. The Asian tsunami of 2004 led to about $10 billion in direct economic losses.

The Kobe earthquake mangled a densely populated and built-up part of Japan, the country’s industrial heartland. It killed 4,571 people and knocked down more than 67,000 buildings. The monetary costs came to about 2.5% of Japan’s 1995 GNP, and led to the failure of financial institutions such as Barings Bank that were deeply invested in the Japanese property market (Japanese property often carried no earthquake insurance).17

While storms and earthquakes often had locally devastating economic effects, droughts by and large did not. In the US, estimated federal expenditures on droughts averaged half a billion dollars a year between 1953 and 1988. Federal costs rose from the 1950s to the 1980s, but even in the worst case, the 1987-89 drought years, did not much exceed $2 billion per year. This is far more than the federal government provided for drought relief during the Dust Bowl decade of the 1930s.18

In general, costs from nature’s shocks rose rapidly. In the 1950s the American total came to roughly $ 4 billion per annum on average. In 2003 that had swollen to $65 billion, and in 2004 to $145 billion, according to Munich Re, the world’s biggest reinsurance firm. About two-thirds of the costs incurred came from floods and storms.

The mass migration into flood-prone regions since 1930, and the consequent creation of housing stock and infrastructure, chiefly accounts for the tremendous rise in the cost of floods and storms. Broward Country in Florida, a regular hurricane victim, had 20,000 people in 1930, and 1.6 million by 2000.19

Although the costs from nature’s shocks rose rapidly, and locally could have devastating effects for a decade or more, none in modern history, not even the 1918-19 influenza, had durable economic consequences that changed the affairs of nations. One could make that claim for the 1346-50 plague pandemic, which is credited with helping to end feudalism in western Europe by raising the negotiating power of laborers. But this event was of unique intensity (it killed perhaps one-third of the population in Europe).

A final consideration regarding the economic implications of nature’s shocks is the possibility of Schumpeterian ‘creative destruction.’ The Austrian economist had in mind crashes in the business cycle and disruptive innovations when he coined this phrase in 1942 to refer to a phenomenon in which bankruptcies eliminated inefficient enterprises, freeing up resources for more efficient use. Taking the response to the plague pandemic in Europe as an inspiration, it is possible to imagine that in the long run brutal destruction of existing infrastructure and plant could clear the way for a new generation of more efficient investment.

This cheerful perspective, it must be said, assumes a shock is followed by a time of stability and other favorable conditions. While the great Lisbon earthquake of 1755 cleared the way for a more economically rational city plan in subsequent years, it is anything but clear that, for example, post-Katrina New Orleans will feature more economically efficient plant and infrastructure. In any case, recurrent shocks would prohibit ‘creative destruction’ even if other circumstances were favourable.

Political and social effects of nature’s shocks defy quantitative measure and all conclusions about them are tentative and subject to dispute. Nevertheless, some generalisations seem reliable.

First, nature’s shocks in the past have proven both socially divisive and unifying at the same time. This is easily visible in the Katrina disaster, in which looting was widespread and citizens preyed upon one another in various disturbing ways. Moreover, the challenges of responding to a disaster on that scale exacerbated political and social cleavages, as various officials and groups blamed one another for mismanagement (not without cause).

At the same time, however, citizens throughout the U.S. donated money, materials, and labor in solidarity with the Katrina victims. So did populations in dozens of countries overseas. Such paradoxical responses are probably the norm.

Second, social conflict on some scale was routine during and after disasters. Societies with little in the way of safety net, say Ethiopia in the 1970s and 1980s, easily succumbed to banditry, ethnic and religious violence, and even outright civil war under the stress of acute drought.20 Restraint and civility can quickly perish when confronted with imperious necessity.

Third, political reaction to shocks often took the form of scapegoating minorities or foreigners. The Black Death in Europe intensified persecution of Jews, who were accused of causing the pestilence, usually by poisoning wells. This played some role in encouraging Jewish migration to Eastern Europe in the 14th century.21

After the great 1923 Kanto earthquake in Japan, which killed some 130,000-150,000 people, vigilante mobs together with army and police units attacked the Korean community of Tokyo, then about 30,000 strong, and killed perhaps 6,000. Many Japanese believed rumors that Koreans had set fires and poisoned water supplies in the earthquake’s aftermath.22

Frequently, in the wake of disasters, government authorities attracted popular wrath, either for neglect or for intrusive efforts to minimise or prevent damage. This is by and large a modern phenomenon, a reflection of the state’s assumption of responsibility for public health and order. The cholera epidemics in Europe of the 19th century intensified divisions within society and contributed to the revolutionary spirit of the era 1830-71.

Cholera was a fearsome scourge that killed quickly and seemed to come out of nowhere (it was communicated by a bacillus that thrives in warm water and came from South Asia). Urban populations with unsanitary water were especially victimised, which in the context of the times gave rise to the widespread belief that the upper classes or the state were systematically poisoning the poor.

Government efforts at quarantines, compulsory hospitalisation, and cordons sanitaires provoked riots and attacks upon state officials. While popular reactions to cholera and to state efforts to control it cannot be said to have caused the revolutions of 1830 or 1848, they surely contributed to the distrust of authorities and class antagonisms that underlay these uprisings.23

Echoes lasted as late as the 1910-11 cholera epidemic in Apulia (Italy), to which the authorities reacted by encouraging pogroms against gypsies and forceably detaining and isolating the sick. Italians responded by rioting and killing medical officials, which led the state to call in the army.24

In the course of the 19th and early 20th centuries, states took more and more responsibility for public health. Compulsory inoculation against smallpox, pioneered by George Washington in the Continental Army – he probably would have lost the Revolutionary War without this step25 – set an example that inspired much imitation once vaccines were developed against commonplace diseases.

In Rio de Janeiro poor neighborhoods revolted against public health campaigns involving smallpox vaccination and mosquito control as a measure against yellow fever in 1904-5.26

In colonial contexts this sort of political turmoil as a reaction to government efforts to check epidemics or other natural disasters was often still more pronounced, and rumors of deliberate biological warfare more frequent. In colonial Mexico, for example, droughts often preceded peasant uprisings, not merely because drought meant hunger, but also because at such times the distribution of irrigation water seemed especially unfair, whereas in times of plentiful rainfall it mattered less.27

Efforts to control outbreaks of sleeping sickness in colonial East Africa, which involved resettlement schemes, quarantine of livestock, and other intrusive measures, regularly provoked local rebellions against British rule.28 In West Africa, along the coast of what is now southeastern Ghana, coastal erosion which the colonial government declined to address, helped push the local population into political resistance to colonial rule.29

British efforts to improve public health in colonial India, and especially to contain the many epidemics of the years 1890-1921, frequently ran afoul of local sensibilities and aroused ire that easily translated into political resistance.30 In the right social and political circumstances, natural shocks, and perceptions of official reactions to them, could precipitate resistance and rebellion.

In one sense, this was nothing new. In most precolonial African societies, and in imperial China (before 1911) as well, populations normally believed that proper ecological functioning, meaning the absence of floods, droughts, epidemics and so forth, depended on a proper relationship between their rulers and heavenly powers.

Natural shocks, therefore, represented a breakdown in that relationship and an inevitable loss of moral authority for rulers. Floods and droughts were taken to mean rulers had lost their efficacy—lost the mandate of heaven in Chinese parlance—and thus no longer were owed obedience. This obviously invited political turmoil.

In the 19th and 20th centuries, when states increasingly sought and took responsibility for disease control, flood control, drought relief and so forth, they inadvertently put themselves in the vulnerable position of Chinese emperors. If natural shocks were not properly managed, in some instances if they were not prevented, the blame lay with the state.

Legitimacy became hostage to the whims of nature. So, while states improved their capacity to deal with nature’s shocks, they were held to ever higher standards, expected to cope effectively with them, but not to intrude too deeply upon citizen’s lives and lifestyles. At times rulers invited trouble by encouraging lofty expectations.

France’s Emperor Napoleon III in 1857 addressed parliament with the great Alpine floods of 1856 as well as the revolutions of 1848 on his mind: “By my honor, I promise that rivers, like revolution, will return to their beds and remain unable to rise during my reign.”31 Such boasts did nothing to enhance his moral authority.

The political significance of nature’s shocks normally played out on local or national scales and touched international politics only indirectly. When they did affect international politics, they exhibited the same paradoxical power to bring nations together and to push them into conflict.

Since at least the 18th century natural disasters have occasionally provoked outpourings of sympathy, both among populations and among states. A notable recent example came in August and September 1999, when earthquakes hit first Izmit in Turkey and then a suburb of Athens, Greece. The Greek government was the first to come to the aid of Turkish earthquake victims, and weeks later the Turks reciprocated.

Ordinary Greeks and Turks donated money and supplies to help earthquake victims in the other country. This came against a background of long enmity between the governments and populations, and helped considerably in defusing a long-simmering rivalry and reorienting politics across the Aegean. In this case, of course, political conditions had to be right for a rapprochement before earthquake diplomacy could yield such results.

Epidemics, while providing plenty of opportunity for mutual recrimination, probably brought states together more often than drove them apart. The obvious rewards to international cooperation in disease control put the incentives clearly in favor of harmonised actions wherever possible, and against giving vent to frustrations with inadequate measures taken by neighboring states.

Since the establishment of the International Red Cross, the World Health Organisation and other such entities, whether global or regional in scope, the integration of disease control efforts by multiple states has become routine, and rarely the occasion for conflict. One exception to this rule is the position taken by Thabo Mbeki and other South Africans on HIV/AIDS, which they sometimes attributed to malevolence on the part of Americans and Europeans.32 Even this, however, did not fundamentally affect relations between South Africa and the West.

Sometimes, of course, nature’s shocks exacerbate international or intersocietal conflicts. Earthquakes, hurricanes, volcanic eruptions have rarely if ever done so, because they are so localised in their effects. Droughts were another matter. The greatest revolt in the history of Spanish America, that of Tupac Amaru in the Andes in 1780-82, coincided with one of the worst droughts of the millennium.

Thousands of desperate peasants rallied to his standard, which in better times would have appealed to far fewer. In another dramatic case, in southern Africa in the decades between 1820 and 1830, recurrent drought converted routine competition for grazing land and food into systemic conquests of the weak by the strong. The mfecane (‘crushing’) created a torrent of refugees throughout southern Africa, and resulted in the formation of powerful new states, such as the Zulu kingdom.33

Drought was also a spur to the slave-raiding that fed the Atlantic slave trade between 1550 and 1850: when food was scarce one of the few ways to get it was to capture people and trade them for food from afar. Indeed progressive desiccation – secular climate change – in the West African sahel drove mounted slave raiders deeper and deeper into West Africa in the years after 1600.34

Throughout the semi-arid zones of the world, where drought was a regular risk, pastoralists and cultivators often uneasily shared frontier zones. Droughts, locust plagues, or any natural shock, created desperation and drove otherwise peaceful communities to attack their neighbors; and weakness born of drought (or some other shock) aroused the cupidity of nearby peoples or states.

The most common format for such violence was attacks by pastoralists upon settled villages, a common pattern in world history in semi-arid areas from Manchuria to Senegal. Such attacks of course took place without the provocation of drought, but drought made them more frequent. In northern Syria and Iraq, environmental shocks of one sort or another came once every 5 or 6 years on average, and often brought political violence in their wakes. Villagers had every reason to support a strong state in hopes of keeping pastoralists in check.35

While drought was probably the most politically dangerous of all nature’s shocks in the deeper past, in the last 100 years water management schemes have often blunted its impact. Moreover, violent political conflict has become more often the affair of urban-based states, rather than pastoral tribes and confederacies, and such states have found it imprudent to go to war to resolve problems created by drought.

Even the potentially divisive cases of international river basins such as the Indus, the Mekong, or the Nile have so far been the subject of successful diplomacy rather than military conflict. While observers in recent decades have often foreseen ‘water wars,’ in these and other contexts, it has yet to happen, and indeed it has not happened for several millennia, if ever.36

The historical record suggests that with well organised states, the probability of warfare arising from drought-induced water shortage is low; the risk rises in the presence of weak states within which those components of society most aggrieved by drought are less constrained in their responses.

Before departing the subject of political reverberations from nature’s shocks, it is worth considering whether or not there exists an analogue to creative destruction in the political realm. Can natural shocks shake a society and state out of harmful complacencies and create the political will to undertake needed reforms? Can they discredit the least efficient parts of the political apparatus so thoroughly as to create new space for the more efficient? Perhaps so, if conditions are ripe for reformism anyhow and if the gales of destruction are not so powerful as to destroy the state entirely.

The Dust Bowl in the US, for example, gave rise to a useful reform in the creation of the Soil Conservation Service, which has helped prevent the recurrence of catastrophic erosion on the scale of the 1930s despite droughts in subsequent decades that were equally or more severe. The 1755 earthquake in Lisbon provided the Marques de Pombal with an opportunity to push through fundamental reforms in Portugal.

The bubonic plague that harrowed Russia in the 1770s, and the cholera epidemics of 19th-century Europe both led to major reform efforts in municipal and national governments. Disappointing responses to hurricanes in 19th-century Cuba had similar effects.37 This may amount to a small silver lining in the dark cloud of natural disaster, in the same way that losing a war or undergoing economic depression served as spurs for reform—provided something survived to be reformed.

Religious turbulence has long been a normal social reaction to nature’s shocks. Throughout history most people understood plagues, hurricanes, droughts and so forth as divinely ordained or the work of evil people with supernatural powers. Hence extraordinary natural shocks often brought heightened religiosity, either in the form of more intense devotion to traditional religions, or more defections to innovative religions or cults.

The rise of the Lotus Sect in Japan, was abetted by a great earthquake in Kamakura, among Japan’s chief Buddhist centres, in 1257. The recurrent bubonic plague epidemics in Europe after 1348 gave rise to all manner of eccentric religious practices, most famously a sect of self-flagellants who wandered about renting their flesh in imitation of Jesus’ sufferings (when not occupied murdering Jews and clergymen).

The Neapolitan cult of San Gennaro derives from the experience of 1631 when Naples avoided harm in a great eruption of Mt. Vesuvius. The New Madrid earthquakes of 1811-12, following on serious floods in the Ohio and Mississippi basins, helped the prophet Tecumseh – who allegedly predicted the earthquakes – rally Native Americans to his religious war against the United States.

It also prompted many white Americans to experiment with eccentric religious doctrines.38 The severe drought of 1991-92 in Zimbabwe, often called the worst in living memory, gave rise to at least three charismatic religious movements as Zimbabweans found divine explanations for their misfortunes more satisfying than hypotheses about perturbations in the Intertropical Convergence Zone.39

There is rarely a shortage of people charismatic and persuasive enough to make a convincing case (for those ready to be convinced) that any extraordinary event is a sign that religious reform is needed. It would be interesting to know whether the Katrina disaster brought an upsurge in religiosity along the Gulf Coast. In any case, if the future holds more serious extreme weather events, it seems likely that the most extreme will generate new forms of religion and intensified commitment to old ones.

16J.R. McNeill, Something New Under the Sun (New York: Norton 2000), 361, based on Angus Maddison, Monitoring the World Economy (Paris: OECD, 1995).
17City of Kobe, “The Great Hanshin-Awaji Earthquake Restoration Project: Statistics and Restoration Progress,” (2005). Viewed at: http://www.city.kobe.jp/cityoffice/06/013/report/january.2006.pdf
18More presumably was spent at state and local levels in drought relief. Western Governors Association, “Western Drought Facts and Information 2004,” viewed at: http://www.westgov.org/wga/testim/drought-fact04.pdf. See also W.E. Riebsame, S.A. Changnon, and T.R. Carl, Drought and Natural Resources Management in the United States: Impacts and Implications of the 1987–89 Drought (Boulder CO: Westview Press, 1991).
19Holli Riebeeck, “The Rising Cost of Natural Hazards,” (2005) viewed at: http://earthobservatory.nasa.gov/Study/RisingCost/printall.php
20Sven Rubenson, “Environmental Stress and Conflict in Ethiopian History: Looking for Correlations,” Ambio 20(1991), 179-182.
21Catherine Park, “The Black Death.” In: K.N. Kiple, ed., The Cambridge World History of Human Disease (New York: Cambridge University Press, 1993), 612-15.
22Zeilinga de Boer and Sanders, Earthquakes, 188-9. Details available in Sonia Ryang, “The Great Kanto Earthquake and the Massacre of Koreans in 1923: Notes on Japan’s Modern National Sovereignty,” Anthropological Quarterly 76, 4(2003), 731-48.
23Louis Chevalier, ed., Le Choléra: le première épidémie du XIX siècle (La Roche-sur-Yon, 1958); Richard Evans, “Epidemics and Revolutions: Cholera in Nineteenth-century Europe,” in Terence Ranger and Paul Slack, eds., Epidemics and Ideas: Essays in the Historical Perception of Pestilence (Cambridge: Cambridge University Press, 1992), 149-73.
24Frank Snowden, Naples in the Time of Cholera, 1884-1911 (New York: Cambridge University Press, 1995).
25Elizabeth Fenn, Pox Americana: The Great Smallpox Epidemic of 1775-1782 (New York: Hill & Wang, 2001).
26N. Sevcenko, A revolta da vacina: mentes insanas em corpos rebeldes (São Paulo: Scipione, 1993).
27Georgina Enfield, Climate and Society in Colonial Mexico: A Study in Vulnerability (London: Routledge, forthcoming 2008); D.S. Brenneman, “Climate of Rebellion: The Relationship Between Climate Variability and Indigenous Uprisings in Mid-Eighteenth-Century Sonora.” Ph.D. dissertation, University of Arizona, 2004.
28Kirk Hoppe, Lords of the Fly: Sleeping Sickness Control in British East Africa, 1900-1960 (Westport CT: Praeger, 2003).
29Emmanuel Akyeampong, Between the Sea and the Lagoon: An Ecohistory of the Anlo of Southeastern Ghana (Athens OH: Ohio University Press, 2001).
30David Arnold, Colonizing the Body: State Medicine and Epidemic Disease in Nineteenth-century India (Berkeley: University of California Press, 1993).
31Quoted in Michael Bess, The Light-green Society:Ecology and Technological Modernity in France, 1960-2000 (Chicago: University of Chicago Press, 2003), 57.
32Theodore F. Sheckels, “The Rhetoric of Thabo Mbeki on HIV/AIDS: Strategic Scapegoating?” Howard Journal of Communications 15(2004), 69-82.
33Elizabeth Eldredge, “Sources of Conflict in Southern Africa, c. 1800-1830: The Mfecane Reconsidered,” Journal of African History 33(1992), 1-35.
34James Webb, Desert Frontier: Ecological and Economic Change along the Western Sahel, 1600-1850 (Madison: University of Wisconsin Press, 1994); Joseph Miller, The Way of Death: Merchant Capitalism and the Angolan Slave Trade, 1730-1830 (Madison: University of Wisconsin Press, 1988).
35Magnus Widell, “Historical Evidence for Climate Instability and Environmental Catastrophes in Northern Syria and the Jazira: The Chronicle of Michael the Syrian,” Environment and History 13(2007),47-70. The data used here are from AD 600-1200. The broader pattern was described in the 14th century by Ibn Khaldun, The Muqaddimah (Princeton: Princeton University Press, 1967), based on his experiences in North Africa.
36Sandra Postel and Aaron Wolf, “Dehydrating Conflict,” Foreign Policy 126(September-October 2001), 60-67. Thomas Homer-Dixon, “On the Threshold: Environmental Changes As Causes of Acute Conflict,” International Security 16(1991), 76-116; Homer-Dixon, “Environmental Scarcities and Violent Conflict,” International Security 19(1994), 5-40.
37Tim Flannery,John Alexander, Bubonic Plague in Early Modern Russia: Public Health and Urban Disaster (Baltimore: Johns Hopkins University Press, 1980); Louis Perez, Winds of Change: Hurricanes and the Transformation of Nineteenth-century Cuba (Chapel Hill: University of North Carolina Press, 2001).
38Zeilinga de Boer and Sanders, Earthquakes, 133-5, 190-2. James L. Penick, The New Madrid Earthquakes (Columbia: University of Missouri Press, 1981), 111-26.
39Hezekiel Mafu, “The 1991-1992 Zimbabwean Drought and Some Religious Reactions,” Journal of Religion in Africa 25(1995), 288-308.