BLUE DEATH IN BENGAL - Tambora: The Eruption that Changed the World - page 43

the depressurized atmosphere over the Indian continent. The winds abruptly swerve north-
east, 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.
Figure 4.3. A synoptic map showing the major weather systems associated with monsoonal fluctuations
across South Asia. In summer, a low-pressure system over land results in the influx of moist air from the
Bay of Bengal, while in the winter dry season the reverse occurs: a high-pressure system drives moisture
away from the landmass. (Bin Wang, ed., The Asian Monsoon [Berlin: Springer, 2006], 145.)
But in the Tambora year 1816, these rains wouldn't come. 13 As long as the volcano's
sulfate veil cooled the Earth, inhibiting evaporation from the ocean and deflating the tem-
perature 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 erup-
tion, with the strong likelihood of “large reductions” in summer rainfall in South Asia. 14
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 ecosys-
tem 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.