Tambora: The Eruption That Changed the World (13 page)

A 1999 study of ash deposits in the Arabian Sea off the coast of modern-day Pakistan indicates a heavy aerosol load in the subcontinental atmosphere in the aftermath of Tambora’s eruption.
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By the time of its arrival in the Indian subcontinent, however, the Tambora cloud had already lost the greater part of its initial volume. Of the vast mass of rock and ash blasted into the upper atmosphere on April 10 and 11, most particles were too large to remain airborne, cascading gently into the tropospheric realm of clouds and weather—there to be washed out of the sky by rain. This great husk of matter shed, Tambora’s sleek, residual cloud—made up of pulverized mineral matter, gases, and sulfate aerosol particles less than a micron in thickness—would hang at altitude for more than two years.
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Tambora’s impacts on the Indian monsoon were not immediate. The sheer presence of a large volcanic cloud in the stratosphere is less important than the sequence of chemical reactions it sets in train. Released from their eon’s residence in the earth, Tambora’s sulfate gases embraced the freedom of the oxygen-rich sky by forming new molecular combinations: first sulfur dioxide then, with increasing oxidization and interaction with water vapor, tiny droplets of sulfuric acid. As the months passed, the volcanic aerosols, further plumped by water vapor drawn to their acidic content, reached a crucial tipping point: around the end of 1815, Tambora’s aerosols attained a density sufficient to interact with both the sun’s rays
and
the radiative heat from the earth, reflecting incoming solar energy back to space (the albedo effect), while at the same time intercepting longwave radiation from the surface.

The sum of these effects was a hotter stratosphere but a net cooling of surface temperatures, initiating a three-year depression of the thermal cycle of the South Asian continent, and ultimately the globe. This depression of summer minima and maxima—at the height of the growing season—proved devastating to farmers in the temperate zones of the North Atlantic in 1816 and 1817. But in the tropical latitudes of South and East Asia, raw surface temperature decline was less important than the impact of a disrupted thermal synchrony between land, sea, and sky on the life-giving monsoon.

The ecology of the Bengali river delta is inseparable from its monsoonal climate. From their first encounter with the South Asian continent, European travelers identified the monsoon as its defining cultural and economic driver. Dry through much of the year, the land would be uninhabitable but for the awesome three-month deluge that replenished aquifers and generated crops. In addition, monsoonal winds brought trade. For centuries before the British arrival in the 1700s, Arab merchants—and later the Portuguese and Dutch—had sailed the monsoonal courses to India and Africa, where they bought spices and slaves to sell on the Mediterranean market.

In the dry, cooler months from November to March, the prevailing winds in India come from the north. Then in May, the geophysical mechanisms of the Indian wet monsoon begin to stir.
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As the Earth’s summer tilt draws the sun’s maximum heat to the latitudes just north of the equator, the land responds more quickly to the increased solar input than does the vast thermal sink of the Indian Ocean. The temperature gradient between land and ocean steepens, awakening the cloud-bearing monsoonal winds from the south, which rush en masse into the depressurized atmosphere over the Indian continent. The winds abruptly swerve northeast, according to the rotation of the Earth, and head directly for the Bengal delta, bearing storm clouds that brood and toil over the Indo-Gangetic plain for weeks on end, powered by an atmosphere crackling with energy. Cooling as it rises over the heated earth, the moisture condenses, depositing wave after wave of torrential rains onto the parched earth in the form of cataclysmic storms. At the height of this annual meteorological drama, the Ganges River takes to imitation of its ocean neighbor: gale winds from the south turn the river current against itself, propelling storm surges over the stone
ghauts
, bringing down houses built too daringly near the banks, while river traders moor their craft to the shore, hoping to survive long enough to enjoy the blessings of the
sharif
, the monsoon crop.

But in the Tambora year 1816, these rains wouldn’t come.
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As long as the volcano’s sulfate veil cooled the Earth, inhibiting evaporation from the ocean and deflating the temperature differentiation of land and sea, the Indian monsoon lacked its vital motive fuel. In a recent climate modeling study that examined the impact of tropical volcanoes on the Asian monsoons, scientists from the National Center for Atmospheric Research found “significant” alteration in the hydrological cycle of the monsoon in the aftermath of a high-impact eruption, with the strong likelihood of “large reductions” in summer rainfall in South Asia.
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Across the breadth of the Indian Ocean, the trade winds faded, stalling thousands of ships on their westward course. Farmers on the Ganges plains waited in vain for the expected shift of winds to the south bearing ocean-fed storm clouds. For the vital
sharif
, timing was everything. But when to plant? No chorus of birds gave the familiar sign, levitating above the trees like flags before the arriving wind. In the absence of the seasonal rains, essential ecosystem services for the human population of the Ganges delta deteriorated rapidly. Because of the inwelling tides from the bay, the river waters were considered poor for drinking. Ordinary people relied on rainwater ponds, called “tanks,” while the affluent drew upon sweetwater artesian wells. In the absence of monsoonal replenishment, tanks and wells alike grew fetid. For desperate Bengali villagers, the failure of the monsoon represented a divine judgment. They reflected now on what terrible sins had been committed in their communities for the monsoon to forsake them so completely. Through the middle months of 1816, prayers and
pujah
ceremonies rang through Hindu temples all along the Ganges. The holy men consulted the stars or divined the intent of the winds from the smoke of coconut oil burned in its shell.

During this driest of Indian Mays, wild fluctuations between excessive cold and record heat saw Bengalis and Europeans alike “drop down dead in the streets.”
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This regional South Asian heat wave, in an era of
general volcanic cooling, may be explained by an enhanced meridional circulation. In the northern hemisphere, Tambora’s stratospheric impact prompted an outflow of Arctic air to the temperate zones of Europe and New England, cooling the landmasses. Meanwhile, on the subcontinent of India, a counterbalancing circulation, possibly allied with a cyclical El Niño system, produced a northerly poleward flow of tropical air through Bengal, spawning localized heat spikes and drought. For the suffering Bengalis, the June rains were inexplicably scanty. Vital tributary streams across the delta dried up, threatening the rice crop. This crippling monsoonal break, lasting until late August at least, is the longest in the historical record of the Asian subcontinent. A tree-ring study of Himalayan cedars from 2007 shows an “extreme low growth” in trees all across the river basins of northern India in 1816, an indication of severe moisture stress.
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When, too late, the volcanic retardants in the atmosphere were overcome and the depressed monsoonal machine returned to furious life, the now unseasonal rains it carried were ruinously extreme. The drought of 1816 subsequently gave way to hundred-year floods, bringing a second season of failed crops, famine, and misery to Bengal. In September, typically a month of monsoonal decline, monster storms inundated the delta on a scale remarkable even in a region accustomed to seventy inches of seasonal rain. Various local disease outbreaks—designated “Bilious Fever” or simply “Malignant Sore Throat” by perplexed British doctors—took hundreds of victims. In the 59th Regiment stationed in Jessore, north of Calcutta, as many as a dozen soldiers perished daily, while the banks of the rivers across the Ganges delta were “covered at all times with the dead and the dying” from the local villages.
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All this, however, was but an overture to the main act of the Tambora climate emergency in India.

DEATH ON THE GHAUTS

As bad as 1816 had been, 1817 in Bengal began like no other year. January and February were looked forward to as months of serene weather:
cold, clear nights and morning fogs rising like a curtain onto sunny days freshened by breezes from the great mountains to the north. But Tambora’s second year announced itself instead with clouds and heavy rain. The winds veered crazily from the north to the east, then to the south, bringing drenching downpours. On March 21, an unprecedented hailstorm destroyed the spring grain crop and tore up orchards of dates, bananas, and papaya all across the fragile alluvial plain.

The disease cholera had been seasonally
endemic
to Lower Bengal since time immemorial. Traveling the narrow coastal roads of the Sunderbans in the Bay of Bengal today, one still comes across shrines dedicated to Ola Bibi, the goddess of cholera.
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But in May 1817, when the monsoon arrived three weeks early and delivered further calamitous quantities of rain to the delta region, the perennial Bengal cholera suddenly appeared out of season, showing unusual strength and breadth. By August an unprecedented “epidemic” of the disease had spread among the Indian population. A short month later an official report declared cholera to be “raging with extreme violence” through both the Indian and European populations of Bengal but also embarking on an unprecedented outward course to the north and west, following the river.
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For the early nineteenth-century European tourist, the uncultivated riverbanks of the Ganges offered the gratifying sight of monkeys, buffalo, and occasional elephants wallowing in the mud. On the river itself water-loving lotus flowers and lilies brushed along the boat’s hull, signs of the nutrient-rich ecology of the delta. “A paradise of flowers,” was one Englishwoman’s commentary on her pleasure trip from Calcutta to Benares.
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At a bend in the river, the source of these botanical offerings might hove into view. The local
ghaut
—broad stone steps leading directly to the river—served as a kind of Indian town square and impressed foreigners as a grand forum of daily village life. From first light, people could be seen washing clothes and bathing, while women bore jars of water on their heads back up the steps. At the summit of the
ghaut
invariably stood a temple, where dedications were made to the sacred river on which all these essential activities depended.

In 1817, this vivid, public life of the
ghauts
was transformed by cholera into a parade of horrors. All along the Ganges River, the busy tempo of village life gave way to mourning and public immolation of the dead. In the eyes of one English traveler, a clergyman named James Statham, the cholera epidemic transformed the vibrant and picturesque river life of the Ganges into a scene from Dante’s Hell:

None but those who have witnessed the distressing sight can form an adequate picture of human misery which the
ghauts
afford at the time when the cholera rages. The dead and dying are all huddled together in a confused mass, and several fires are blazing at the same time, consuming the bodies of the more rich and noble, who have just died, whilst the poor creatures who are expiring feel certain that in a few minutes their bodies must share the same fate, or be hurled into the flowing stream, to become the prey of waiting alligators, or, what is worse, to be left on the beach, a prey to jackals and vultures, which infest the spot. Fresh arrivals every hour multiply the misery, as groans and cries increase, while the stench proceeding from the burning bodies, and the lurid gleams of the blazing fires reflected by the water, and giving somewhat of an unearthly appearance to the features of the suffering victims around, furnish a scene of woe which completely baffles the power of description to portray.
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An almost hysterical fear of this new, insatiable cholera—inspired by its shocking symptoms and territorial expansion—seeps through the restrained bureaucratic prose of British colonial officials. The epidemical “cholera morbus” was an “evil,” “a horrid scourge,” “an awful and desolating calamity” that “threatened to sweep off a large portion of the Native population” if some means could not be found to counteract it. It was “a malady more destructive in its effects, and more extensive in its influence than any other recorded in the annals of the country.” As a consequence of this high mortality and general panic, the cholera threatened social order, the proper running of the Indian economy, and thus company profits. “Much mischief has arisen,” complained the Board of Revenue in Calcutta, “from the great alarm of the people, their quitting their habitations and their proper pursuits.”
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Death counts were hazy, perhaps inflated, and suspiciously round. Certainly thousands, perhaps tens of thousands, died in the first season. By the 1830s, at the beginning of the global cholera panic, European estimates of Indian fatalities since 1817 would run into the millions, numbers impossible to verify.
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