Climate change has almost extinguished life on earth on three occasions. Some 250 million years ago, a series of volcanic eruptions in Siberia altered the earth's atmosphere, wiping out 90 percent of plant and animal species. Next, 65 million years ago, an asteroid struck what is now Mexico and created an atmospheric catastrophe that eliminated 50 percent of the earth's species (including the dinosaurs). Finally, some 73,000 years ago, the eruption of Mount Toba, in Indonesia, caused a "winter" that lasted several years, apparently killing off most of the human population.
No subsequent environmental disaster has had an impact on that scale, but climate change has caused widespread destruction and dislocation. About 13,000 years ago, the Northern Hemisphere experienced an episode of cooling (probably after a comet collided with the earth) that wiped out most species there. In the 14th century, a combination of climatic oscillations and major epidemics caused severe depopulation and disruption in much of Europe and Asia. In the 17th century, the planet experienced some of the coldest weather recorded in the past millennium. To the English poet John Milton, who experienced these catastrophes, it seemed like "a universe of death."
So far, most attempts to predict the consequences of climate change look to the future by building on recent trends, but another methodology exists. We can look back to a past climate-induced catastrophe, using sources created by both humans (narrative and pictorial as well as archaeological) and nature (above all, annual ice-core and tree-ring data). In a 2012 article in The American Historical Review, Julia Adeney Thomas, an associate professor of history at the University of Notre Dame, reminded her colleagues that "climate change—or climate collapse—and all of its related global transformations" is "a world-altering force," one "more devastating, and more definitive" than any other. She called for an "environmental turn" in the field, one that foregrounds climate as a protagonist in human affairs.
The evidence for major climate change in the 17th century is both copious and unambiguous. Consider the year 1675. In July, the Paris socialite Madame de Sévigné complained to her daughter, who lived close to the Mediterranean: "It is horribly cold: We have the fires lit, just like you, which is very remarkable." She added: "We think the behavior of the sun and of the seasons has changed."
Madame de Sévigné was correct on both scores: 1675 is one of the few years with an exceptionally cool summer on record, and the narrow tree rings from that time reveal unusually poor growth; both grape and grains ripened later than at any other time in the previous five centuries. As for the sun, much of the 17th century saw a remarkable aberration: an almost total absence of sunspots, those dark regions of intense magnetic activity on the solar surface surrounded by flares that make the sun shine with greater intensity. The development of telescopes after 1609 enabled observers to track the number of sunspots, but although astronomers around the world stared at the sun on more than 8,000 days between 1643 and 1715 (the duration of the reign of Louis XIV, popularly known as the Sun King), the grand total of sunspots they observed scarcely reached 100, fewer than appeared in even a single year of the 20th century.
Nevertheless, it took human stupidity to turn crisis into catastrophe. The meager French harvest of 1675 occurred just as the king raised new taxes to pay for his wars, with predictable results. Many people died of hunger, many more migrated in search of food, and in the west of France, many took part in the "red bonnets" revolts. Most striking were the signs of hardship written on the bodies of survivors. Government officials in France compiled data on each man who enlisted in the royal army, including his height; those born in 1675 stood on average just five feet tall, the shortest cohort of Frenchmen ever recorded.
The earth also experienced an unusually cold winter in 1620-1, when the Bosporus froze so hard that people could walk across the ice between Europe and Asia—a climatic anomaly. The summer of 1627 was the wettest recorded in Europe for 500 years, and 1628 was another "year without a summer," with temperatures so low that in many areas food crops never ripened. From 1629 to 1632, northern India suffered a catastrophic drought, while much of Europe suffered excessive rains. In the Alps, unusually narrow tree rings reflect poor growing seasons throughout the 1640s, and glaciers advanced more than a mile. In the Northern Hemisphere, 1641 saw the third-coldest summer recorded over the past six centuries; 1641-2 was the coldest winter ever recorded in Scandinavia; and 1649-50 was the coldest winter on record in both northern and eastern China.
Climate change on this scale seems to have triggered an unusual concentration of extreme weather events. In France, the river Seine has experienced 62 recorded floods, 18 of which occurred in the 17th century. Grape harvests in western France between 1640 and 1643 began a full month later than usual, producing wine too bitter to drink, while grain prices surged as a result of poor cereal harvests. Unseasonable weather in England ruined the corn and hay each year from 1646 to 1651, with five more bad harvests from 1657 to 1661: 11 harvest failures within the space of 16 years. Such abnormal climatic conditions lasted from the 1620s until the 1690s, the longest as well as the most severe episode of global cooling recorded in the past 12,000 years.
Why did this happen? A spate of major volcanic eruptions, including 12 around the Pacific between 1638 and 1644 (apparently an all-time record), produced dust veils that cooled the earth's atmosphere, reducing mean summer temperatures by about 2 degrees Celsius. To a skeptic, such a change seems insignificant. But since the difference between the hottest and the coldest temperatures recorded since the last ice age is no more than 6 degrees Celsius, a change of one-third of the historical maximum is dramatic. In the 17th century, those climatic changes coincided with both political instability and mass starvation.
That century witnessed more cases of state breakdown around the globe than did any previous or subsequent age. In the coldest decade, the 1640s, Ming China, the most populous state in the world, collapsed; the Polish-Lithuanian Commonwealth, the largest state in Europe, disintegrated; much of the Spanish monarchy seceded; and the entire Stuart monarchy rebelled—Scotland, Ireland, England, and its North American colonies. In addition, in 1648 alone, rebellions paralyzed both Russia (the largest state in the world) and France (the most populous state in Europe); while in Istanbul (Europe's largest city), irate subjects strangled Sultan Ibrahim, and in London King Charles I went on trial for war crimes (the first head of state to do so).
Wars also became more frequent. Europe experienced only three years of complete peace during the entire 17th century; the Ottoman Empire enjoyed only 10 such years; and both the Chinese and Mughal empires fought campaigns almost continuously. Civil wars proliferated. For six decades, supporters of the Ming and Qing dynasties fought for control of China. The rebellions of large parts of the Stuart and the Spanish monarchies unleashed internal conflicts that lasted over two decades in the former and almost three in the latter. The Germanic states, with powerful foreign support, fought one another for 30 years. France endured a civil war that lasted five years; the Mughals suffered two wars of succession. Throughout the Northern Hemisphere, war became the norm for resolving both domestic and international problems.
The frequency of popular revolts also increased. In China the number of major armed uprisings rose from under 10 in the 1610s to over 80 in the 1630s, affecting 160 counties and involving well over one million participants. In Switzerland and what is now Germany, of the 25 major peasant revolts recorded in the 17th century, more than half took place between 1626 and 1650. In England, the number of food riots rose from 12 between 1600 and 1620 to 36 between 1621 and 1631, with 14 more in 1647-9. In France, popular revolts peaked, both absolutely and relatively, in the mid-17th century.
The fatal synergy among climate change, revolution, war, and rebellion produced human mortality on a scale seldom seen before and never since. In China, the emperor acknowledged that "over half of the population perished" in the violent transition from Ming to Qing; one of his magistrates wrote, "Many people held their lives to be of no value, for the area was so wasted and barren. ... Every day one would hear that someone had hanged himself from a beam and killed himself. Others, at intervals, cut their throats or threw themselves into the river."
In Europe, a German manufacturer believed that "there have been so many deaths that the like of it has never been heard in human history," while in Spain, the principal minister of King Philip IV argued that "God has chosen to wear out these realms with every calamity—war, famine and plague—each one of which normally suffices to raise great anguish and a sense of panic." In France, a royal judge believed that "two-thirds of the inhabitants of the villages around Paris are dead of illness, want and misery"; and at neighboring Port-Royal-des-Champs, Abbess Angélique Arnauld lamented that "the miseries of our France are such that there are now only few working men, since almost all those in the countryside, ravaged by the war, are dead and the rest have enlisted and gone to the wars." In all, she estimated that "a third of the world has died," and she feared that the general desolation "must signify the end of the world."
Only Japan took appropriate action. Episodes of extreme weather that killed half a million people in the 1630s persuaded the Tokugawa shogun to create more granaries, upgrade communications infrastructure, and avoid foreign wars, in order to accumulate sufficient food reserves to cope with future disasters. So although extreme weather persisted, Tokugawa Japan enjoyed peace and prosperity.
Studying the causes of climate change and the various coping strategies from 350 years ago will not prevent the onset of another catastrophe in the 21st century. Nevertheless, the mean global temperature today differs by one or two degrees from the 20th-century average—the same order of magnitude as in the 17th century—and the fact that we face an increase (rather than a fall) of 2 degrees Celsius has not reduced the frequency of extreme weather events or their adverse impact on humanity. The "millennial floods" of 1997 and 2002 (so called because they were considered once-in-a-millennium events) caused, respectively, $1-billion and $41.2-billion in damage in Central Europe. A summer heat wave in Western Europe that lasted just two weeks in 2003 led to the deaths of 70,000 people. In 2005, Hurricane Katrina killed over 2,000 people and destroyed property worth over $81-billion.
Although Katrina was the costliest natural disaster in the history of the United States, it was only one among 484 reported natural disasters of 2005 around the world, causing a total of $176-billion in damage. That figure held the record until 2011, when, although the total of reported natural disasters fell to 352, the damage they caused exceeded $350-billion. This total included $2-billion from a tornado that struck Tuscaloosa, Ala.; $2.5-billion from a tornado that hit Joplin, Mo.; and $210-billion from the Tohoku earthquake and tsunami, in Japan. Among them, those three extreme weather events killed more than 16,000 people.
No human intervention could have prevented those natural catastrophes—although a better early-warning system, education about evasive strategies, and faster and more effective emergency responses could have mitigated the consequences. Likewise, no human intervention can prevent volcanic eruptions or a decline in the number of sunspots, despite the certainty that they will affect the climate, reduce harvest yields, and thus cause starvation, economic dislocation, political instability, and death. Instead we convince ourselves that these disasters will not happen just yet (or, at least, not to us).
As the paleontologist Richard Fortey has observed: "There is a kind of optimism built into our species that seems to prefer to live in the comfortable present rather than confront the possibility of destruction," with the result that "human beings are never prepared for natural disasters."
Until recently, the fact that almost all people killed and most people affected by natural disasters lived outside North America and Europe fostered the comforting belief in the West that such things happened only "somewhere else"—an assumption encouraged by terms such as "Typhoon Alley" and "The Ring of Fire." That view is not unfounded—the Philippine archipelago really does experience more natural disasters than any other comparable area of the world, with 220 volcanoes (at least 12 of them active), as many as five earthquakes a day, and up to 30 typhoons a year—but natural disasters now also strike North America and Europe as well. Thus, according to a European Commission report, overall losses caused by weather and climate-related events have increased from a decadal average of about $9-billion (1980-9) to more than $17-billion (1998-2007).
Some have learned from history and taken appropriate action. In 1966 the British government asked the scientist Hermann Bondi to assess whether a flood tide might inundate London. A mathematician by training, he devoted much attention to assessing risks, but he also consulted historical sources and found that the height of storm tides recorded at London Bridge had increased by more than three feet since 1791 (when records began). Although he could not explain the reason for the increase, Bondi predicted that it would continue and warned that "a major surge flood in London would be a disaster of the singular and immense kind," one that would deliver "a knockout blow to the nerve centre of the country." He therefore unequivocally recommended the construction of a Thames barrier.
The barrier was completed in 1982, at the stunning cost of $800-million—but it now protects not only the "nerve centre of the country" but also property with a current value of $300-billion, including 40,000 commercial and industrial sites and 500,000 homes, with more than a million residents. It has already been activated more than 100 times, sparing London the fate of New Orleans in 2005 and New York in 2012 in the face of natural disasters that are inevitable. Encouraged by the success of the Thames Barrier, and alarmed by the seemingly inexorable rise in sea levels, Britain's chief scientific officer recently warned, "We must either invest more in sustainable approaches to flood and coastal management or learn to live with increased flooding." In short, we can pay to prepare now or we can prepare to pay much more later.
Unfortunately, the current debate on climate change favors procrastination because it confuses two issues: whether the global climate changes, and, if so, whether humans are to blame. Some people still doubt the second proposition (just as some people still deny that smoking increases the risk of lung cancer), but the 17th-century record leaves no doubt about the first: Climate change occurs, and it can have catastrophic consequences. This cruel calculus has not changed. The global crisis of the 17th century killed millions of people, but a natural catastrophe of similar proportions today—regardless of whether humans are to blame—will kill billions of people. It will almost certainly also produce dislocation and violence, and it will compromise international security, sustainability, and cooperation.
So while we argue over whether or not our climate is changing, and (if so) who is to blame, let us also anticipate—and try to mitigate—the sort of catastrophes that history shows are inevitable.
John Milton, a contemporary of Madame de Sévigné and the Sun King, perceived the dangers posed by climate change with unusual clarity. Blind and confined to his house, he began to compose Paradise Lost in 1658—"the severest winter that man alive had known in England: the crow's feet were frozen to their prey; islands of ice enclosed both fish and fowl frozen, and some persons in their boats," a winter when Massachusetts Bay iced over and the Delaware River froze so hard that deer ran across it. Milton's fictional world, like the real one in which he lived, lay at the mercy of unpredictable and unforgiving climate change.
At certain revolutions all the damned
Are brought: and feel by turns the bitter change
Of fierce extremes, extremes by change more fierce,
From beds of raging fire to starve in ice
Their soft ethereal warmth, and there to pine
Immovable, infixed, and frozen round
Periods of time; thence hurried back to fire.
We should ponder Milton's vision as we debate whether it is better to invest today in preparing for extreme weather, or to face tomorrow the consequences of inaction. After all, unlike our ancestors in the 17th century, we possess both the resources and the technology to make that choice.
Geoffrey Parker is a professor of history at Ohio State University. He is the author, most recently, of Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century (Yale University Press, 2013).