THE SEVEN SORROWS OF YUNNAN - Tambora: The Eruption that Changed the World - page 56

on with a period of drastic climate decline at precisely the wrong historical moment. The
Tambora-driven weather emergency and ensuing famine of 1815-18 fatally altered the course
of Yunnan's development and played its part—as we shall see—in bringing down an empire.
YEARS WITHOUT A SUMMER
Disdained by the filmy Tamboran sun, the Himalayan plateau never warmed during the sum-
mer of 1816, nor did the surrounding oceans. In Tibet, just north of Yunnan, it snowed for
a remarkable three days in a row in July, where a British surveying party reported famine
among the native population and required emergency rations for their own survival. In this
altered volcanic summer, the Tibetan plateau reverted to its wintry role, channeling the cold
northern air southward and eastward toward the Mekong peninsula. Meanwhile, a cool and
subdued Indian Ocean, likewise bereft of its monsoonal power, failed to deliver the warm
winds necessary to moderate the cruel Mongolian northerlies.
Yunnan had the misfortune to suffer a cyclical drought in 1814, which meant its grain
reserves were already depleted even as its normally benign weather patterns fell under Tam-
bora's chilling spell. The first signs of volcanic weather arrived quickly, a month after the
eruption in the spring of 1815. Given the relative coolness of its elevation, Yunnan relied
upon unstinting summer sunshine to ripen its grain crops. But in the late spring of 1815, the
expected southwest winds did not arrive to disperse the clouds, which instead labored over
the mountains, depositing flooding rains that drowned the winter crops. Wheat and barley
sprouted underwater, while row after row of broad beans disintegrated into the mud. The bit-
ter rains continued through the disastrous summer and into autumn. The aqueous rice fields
might yet have survived had it not been for a frosty August, which strangled the budding rice
plants at the critical point of their maturation.
According to one school of agricultural historians, the seven-thousand-year history of do-
mesticated rice production begins in Yunnan. At the time of the Tambora eruption in 1815,
a fifty-year accelerated settlement program had seen Han Chinese pioneers from the east “re-
claim” vast areas of the intramontane lowlands for rice paddies, while picturesque irrigated
terraces climbed ever further up the sheer mountainsides. Rice is a famously hardy crop,
hence its role as the staple diet for half the world's people. Once a rice-growing system is in
place, and refined to allow double or even triple cropping, it will support rapid and continu-
ous population growth, as in the case of eighteenth-century Yunnan. No other plant has the
population-carrying capacity of rice, whose system of air passages connecting its roots and
stem is formidably efficient, enabling it to self-regulate in widely differing contexts from ir-
rigated fields, to dry upland soils, to riverbeds.