The Year Without Summer: 1816 and the Volcano That Darkened the World and Changed History
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To emphasize the unprecedented nature of the cold spell, news reports repeatedly asserted that the oldest living residents in their community could not remember such violent winter storms in the month of June. The Albany Argus, for instance, declared that “the weather, during the last week, has exhibited an intensity of cold, not recollected to have been experienced here before in the month of June.” In Rutland, Vermont, “the oldest inhabitants in this part of the country do not recollect to have witnessed so cold and unfavorable a season as the present,” and in Middlebury, “never before, we are informed, was such an instance known, by even the oldest inhabitants now living amongst us.”
In the absence of reliable weather statistics, individual human memory—and the collective recollections of a community—were the only means of comparison to previous seasons. But this method clearly had its limitations; as the editor of the Albany Daily Advertiser pointed out, “we are very apt to misrecollect the state of the weather from time to time. Memory is certainly not safely to be relied on relative to this subject, for any great length or time.” Hence the Advertiser urged that regular journals of weather observations should be kept throughout the nation. “A great mass of useful information might be collected concerning our climate, and seasons,” the editorial concluded, “if gentlemen who possess the necessary instruments, would be careful to devote a few minutes in each day to mark the state of the weather, and the temperature of the atmosphere.” Even a modest effort on the part of these individuals, the Advertiser predicted, would provide data which “would be of great and lasting importance.”
A number of Americans (besides Jefferson, of course) already had made sporadic attempts to collect weather statistics in a systematic fashion, although a lack of uniformity in instrumentation and methodology limited the usefulness of their data. In the 1740s, Dr. John Lining—a Scottish-born physician living in Charleston, South Carolina—began tracking changes in the weather with variations in his own physical processes, to try to determine the relationship between climate and public health. “I began these experiments,” Lining wrote, “[to] discover the influence of our different seasons upon the human body by which I might arrive at some certain knowledge of the cause of our epidemic diseases which regularly return at their stated seasons as a good clock strikes twelve when the sun is on the meridian.” Several other physicians in the United States maintained their own records comparing weather and public health data in the late eighteenth and early nineteenth centuries, but there was little coordination of their efforts.
In 1778, Jefferson succeeded in compiling parallel weather observations between Monticello and the College of William and Mary in Williamsburg, Virginia, courtesy of the president of the college, who agreed to take daily readings of the temperature, winds, and barometric pressure. The effort lasted for only six weeks, however. Although Jefferson persistently encouraged the establishment of a national system of meteorological observation throughout the last decades of his life, the best he could achieve was an occasional exchange of information with like-minded souls in cities from Quebec and Philadelphia to Natchez and London. The closest the nation came to achieving a coordinated program of weather measurements before 1816 was the thrice-daily observation system established by the consortium of New England colleges—notably Middlebury, Williams, Yale, and sometimes Harvard—of which Chester Dewey was a member.
Such an accumulation of concrete statistical details was precisely the sort of empirical scientific task that appealed to Americans in the early nineteenth century. As Gordon Wood has pointed out, Americans were forsaking the Enlightenment’s fascination with metaphysical principles and abstract generalities in favor of a harder-edged and utilitarian approach to science. By 1816, science in the United States no longer was the preserve of gentlemen with sufficient leisure to contemplate the moral grandeur of natural laws, or pursue knowledge purely for its own sake. Anyone could gather data (assuming one was armed with the proper measuring instruments), or make sense out of statistics accumulated by others. When introducing his Picture of Philadelphia, a detail-laden snapshot of the city published in 1811, physician James Mease declared that “the chief object ought to be the multiplication of facts, and the reflections arising out of them ought to be left to the reader.” Americans increasingly believed that these collections of scientific data should serve a useful purpose; the study of chemistry, for instance, should produce better cider, cheese, or methods for marinating meat. Perhaps the compilation of meteorological data might result in more efficient agricultural practices. And if scientific investigations helped Americans in their ceaseless pursuit of material wealth, so much the better.
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IN the early nineteenth century, most meteorological instruments in the United States and Europe were owned by gentleman scientists, who collected data for their private diaries or to share with their colleagues in learned societies. Many of the rest of the instruments were located on ships: British Royal Navy vessels, for instance, were required to measure the air temperature, ocean temperature, wind speed and direction, and the fraction of the sky covered by cloud four times a day. (In a testament to British military discipline, navy logbooks reveal that ships continued to make regular readings even when taking enemy fire.) Barometers and thermometers were the most common instruments, having been developed over the previous 150 years. While some of the earliest models provided results of questionable accuracy, by 1816 the designs of both instruments had been refined so that they were able to provide precise and reliable measurements of the atmospheric pressure and temperature, respectively.
Anemometers (for measuring wind speed) and hygrometers (for measuring humidity) were far less common and less accurate. There was no standard method for measuring wind speeds until Sir Francis Beaufort’s eponymous scale, developed in 1805, was adopted by the Royal Navy in the 1830s, and wind forces would not be related to anemometer measurements until the 1850s. It is nearly impossible to compare the readings from earlier anemometers, since the designs of the instruments and the scales applied to their measurements varied so widely. Most hygrometers of the early nineteenth century were simply the combination of two thermometers: one kept dry and the other immersed in water. As the water naturally evaporated, it cooled the wet thermometer; the temperature difference between the two thermometers could then be used to determine the humidity. In 1783, the Swiss physicist Horace-Bénédict de Saussure demonstrated the first hygrometer based on the contraction and expansion of human hair due to changes in atmospheric moisture. While his design would later become very popular, in 1816 it had not yet been widely adopted. (Currently, the most accurate hygrometers are polished mirrors that are cooled until water condenses onto them, an adaptation of a technique pioneered by the British chemist John Frederic Daniell in 1820.)
Although barometers and thermometers were in widespread use throughout Europe and the United States throughout the eighteenth and into the nineteenth centuries, many weather diaries remained private; those records that have been published often contain long gaps or end abruptly. The meteorological community was primarily composed of amateurs, albeit enthusiastic ones, rather than professionals. Governments had not yet established official agencies with the responsibility for monitoring or understanding the weather—the Royal Meteorological Society in Britain, for example, was not founded until 1850—and, as during the French Revolution, those that did exist could be disbanded if they became politically unpopular. The information we have today about the climate of the period is the result of the painstaking, meticulous reconstitution by modern climatologists of fragmented data from disparate sources around the globe.
Those nineteenth-century scientists who had access to instruments and kept detailed, regular records would have been aware of the connections between the variations in temperature and pressure and the variations in local weather patterns. Such variations had been noted for nearly two hundred years. Evangelista Torricelli, the Italian physicist and mathematician who invented the me
rcury barometer in 1643, soon recognized that the atmospheric pressure changed from one day to the next. Four years later, famed French philosopher René Descartes made two identical paper scales for a barometer; one he kept, the other he sent to his friend Marin Mersenne “so that we may know if changes of weather and of location make any difference to [the readings].” In 1648, the French mathematician and philosopher Blaise Pascal carried out a series of experiments on mountain peaks, with the help of his brother-in-law, to demonstrate that air pressure decreases with altitude. His findings astonished most contemporary scientists, who assumed the atmosphere’s composition remained constant throughout its depth.
While the amateur meteorologists of the early nineteenth century understood the links between their own atmospheric measurements and immediate changes in their weather, they were unable to forecast the weather more than an hour or two in advance. Having developed reliable, if elementary instruments and a rudimentary understanding of atmospheric physics, there remained three key challenges that would make accurate weather predictions impossible for another 150 years. The first was the speed at which meteorological data could be transferred and collected at a central location. Forecasting the weather requires accurate information about the current state of the atmosphere. A crude, but often effective prediction technique is to simply use the weather from a nearby location upwind of the location for which one is forecasting. If the wind moves at a greater speed than the information, however, even this technique is useless. Not until the development of a widespread telegraph network in the mid nineteenth century could scientists collect meteorological data quickly enough to make these basic forecasts for a few hours ahead, or warn of the approach of severe weather.
To move beyond the simple, upwind forecasting method, meteorologists must understand the circulations of and interactions between air masses around the globe. As scientists continued to develop meteorological instruments through the seventeenth, eighteenth, and nineteenth centuries, they also developed hypotheses to explain the changes in the readings they obtained. Aided by the instruments aboard ships, many mathematicians and “natural philosophers” turned their attentions to the causes of the direction and strength of the transoceanic winds. These projects carried significant potential benefits to them and their government sponsors, since knowledge of the seasonal variations in the paths of the strongest winds would allow merchant vessels and warships to cross the ocean more quickly than their competitors and enemies.
As the British Empire and the Royal Navy expanded during this period, British scientists engaged in a fierce debate over the origin of the east-to-west trade winds (named for their importance in conveying goods-laden ships to the Americas) that blow steadily across the Atlantic and Pacific in both the Northern and Southern Hemispheres. Some supported Galileo’s earlier hypothesis that the winds were caused by Earth rotating more quickly in the tropics than at the poles; the tropical atmosphere could not “keep up” with the spinning Earth below, they argued. To one standing on the ground, rotating to the east with Earth, the wind would indeed appear to blow from east to west. Others, such as the late-seventeenth-century astronomer Edmund Halley, believed that the winds blew from the east because the sun’s energy flowed from east to west during each day. Halley argued that the sun’s energy heated the air, which rose to form a wind; the sun’s movement caused this wind to appear to blow from the east. Halley’s explanation became canon and was widely accepted in the early nineteenth century.
It would be another twenty years after the eruption of Tambora before scientists acknowledged the true explanation for the trade winds. First advanced—with some inaccuracies—by the British lawyer and amateur meteorologist George Hadley in 1735, the theory stated that the trade winds are caused by air trying to flow from each hemisphere towards the equator. When viewed from the perspective of someone standing on the rotating Earth, however, the winds—which are not rotating—appear to curve to the right in the Northern Hemisphere and to the left in the Southern, giving east-to-west winds in both hemispheres. For his contributions, climatologists still refer to the circuit of winds between the equator and the middle latitudes as the Hadley Cell.
Hadley’s theory was often discussed, but the idea of Earth as a rotating frame of reference was difficult for scientists to grasp. Hadley’s principle did not gain meaningful traction until Gaspard-Gustave Coriolis conclusively demonstrated in 1835 the actions of the various forces acting in a rotating reference frame. (Coriolis, incidentally, thought his work would be most useful for those who built waterwheels, or played billiards.)
Many other fundamental principles of atmospheric science relevant to weather forecasting were developed in the decades following the eruption of Tambora, but remained unknown or as working hypotheses to those attempting to explain the cooling climate and extreme weather after 1815. The Navier-Stokes equations, which describe the three-dimensional flow of viscous fluids, including the atmosphere, were derived in 1845, when George Gabriel Stokes updated Claude-Louis Navier’s 1822 formulation. These equations are crucial to describing the ever-evolving state of the atmosphere; today they form the basis for the computer simulations of Earth’s climate that make it possible to predict the weather days and sometimes weeks in advance. Similarly, the Clausius-Clapeyron relationship, which explains that a greater quantity of water vapor can exist in warmer air, was advanced by its namesakes in the mid-1830s. Without the understanding of the global circulation of the atmosphere that these theories provide, the gentleman scientists of the early nineteenth century lacked the knowledge to understand that volcanic eruptions would affect the world’s weather patterns; certainly they could not have forecast the disruption that the eruption of Tambora would create.
Even with speedily transmitted data by telegraph and comprehension of physical laws that govern the atmosphere, meteorologists failed to produce reliable, useful weather forecasts until after the Second World War due to the third and final hurdle: computational speed. The Navier-Stokes equations and the other key atmospheric formulae require computers in order to generate timely forecasts. The human brain simply is not sufficiently powerful, as the early-twentieth-century British mathematician Lewis Fry Richardson discovered when he tried to apply the equations developed in the nineteenth century to real weather observations. It took Richardson nearly three years—working part-time while serving as an ambulance driver during the First World War—to make a six-hour weather forecast for France, a forecast that turned out to be spectacularly inaccurate.
In the absence of data, theories, and computers, amateur meteorologists of the early nineteenth century fell back upon the centuries-old method of pattern recognition when attempting to forecast the weather and climate. They looked for signs from nature—larger than normal berries on trees, an early appearance of acorns, even the thickness of onion skins—as forewarnings of the coming seasons. (Thin onion skins supposedly meant a mild winter.) Links between these signals and the subsequent climate, whether real or imagined, became established in “weather lore” and provided the basis for many almanacs. Such sayings often thrived due to their adherents’ selective memories, attaching greater importance to the instances in which the lore proved accurate than to those (often more frequent) times when it failed. Some meteorologists of the era also proposed associations between the seasons themselves, such as a cold winter following a warm autumn. In some cases modern science has proven these relationships to be correct, but only because the abnormal conditions in both seasons are caused by the same variation in the atmospheric circulation.
4.
THE HANDWRITING OF GOD
“The atmosphere still seems as cold as in March or November…”
ON JUNE 5, President Madison (annual salary: $25,000) left his temporary dwelling in Washington, D.C. (annual rent: $1,814), and headed for Montpelier, his home in Orange, Virginia, about 50 miles south of the nation’s capital. (No one voluntarily spent the summer in the hot, muggy, mosquito-infested District of Col
umbia.) Since Congress adjourned on April 30, the president had spent much of his time negotiating with Britain a reduction in armaments on the Great Lakes. Through the United States ambassador at the Court of St. James’s, John Quincy Adams, Madison also informed Foreign Secretary Lord Castlereagh that the U.S. intended to obtain equal commercial access to export markets—primarily for American grain—in the British West Indies.
Before he left Washington, Madison sailed down to Annapolis to inspect a new U.S. warship; since the president decided the trip was not, strictly speaking, official business, he insisted on paying out of his own pocket the twenty-five-dollar fee due to the sailors who took him down the Potomac. Then a messenger arrived with a letter from the Dey of Algiers, whom the American public regarded as one of the widely despised “Barbary Pirates.” The Dey’s letter was written in Turkish and translated into Arabic, but since no one in the president’s immediate circle could decipher either language, the letter sat, unread, for two months until a translator could be found.
Madison reached Montpelier just in time for the arrival of the cold wave that was devastating New England’s crops. Freezing temperatures had settled over New Jersey and Pennsylvania on June 6 and 7; then frost struck the fields of central Virginia, damaging corn, wheat, and vegetables. “This is an extraordinary spring,” declared a Richmond newspaper. “On Thursday morning last we had a frost in this city.” To make matters worse, the effects of the springtime drought were felt even more strongly in the south than in New England; Charleston, South Carolina, suffered through eight weeks without rain in March and April. “We do not recollect to have witnessed a more distressing drought, than that which at this time visits every portion of our country,” lamented the American Beacon, published in Norfolk. “The temperature of the weather with us is very fluctuating—the evenings and mornings generally so cool as to render a fire quite agreeable. The Earth is so parched…”