42 Essay |The South Asian monsoon The EconomistJune 29th 2019
2 gueagainstinterveninginthe famine which began to spread
across the dry land, eventually claiming 5.5m lives (some esti-
mates say the total was far higher). A couple of years earlier, during
a local drought in Bihar, a major catastrophe had been averted
through imports of rice from Burma. Yet such expenditure on re-
lief had met with much criticism, not least from The Economist.
Such an approach, we wrote, would encourage lazy Indians to be-
lieve that “it is the duty of the Government to keep them alive.”
When famine spread in 1877, the viceroy, Lord Lytton, was deter-
mined that such folly should not be repeated. He vehemently op-
posed district officers’ attempts to stockpile grain, on the basis
that it would distort the market. The railways, built with the help of
taxes that had impoverished the now starving peasants, ensured
that grain could get to where it would fetch the highest price—for
example, by being exported to Britain—rather than stay in place,
unprofitably saving lives. The administration cut both relief ra-
tions and the wage for a punishing day’s work in the relief camps,
limiting the victims’ access to markets yet further.
A century later, Amartya Sen, a Nobel-winning economist, ar-
gued that what happened in the 1870s was the rule, not the excep-
tion: governments are the general cause of famine. Mass starva-
tion is not brought about by a crop-disease- or climate-driven
absolute lack of food but by policies and hierarchies which stop
people from exchanging their primary “entitlement”, in Mr Sen’s
terms—for instance, their labour—for what food there is. Such
policies are a feature of autocracies; where the entitlements of the
people include real political power, as they do in functioning de-
mocracies, they are normally untenable. It was an academic in-
sight born of childhood witness. As a child Mr Sen lived through
the Bengal famine of 1943, during which Indians died in the street
in front of well-stocked shops guarded by the British state.
That famine, in which up to 3m Bengalis died, followed a devas-
tating cyclone. But much of the damage was done by the scorched-
earth policy of colonial officials who, fearing a Japanese invasion,
burned the vessels that local cultivators used to ship rice. Britain
sent no relief, in part, perhaps, because of Winston Churchill’s ac-
tive dislike of Indians agitating for independence. Jawaharlal Neh-
ru, who would later become India’s first prime minister, but was at
the time imprisoned by the British, wrote from jail “that in any
democratic or semi-democratic country, such a calamity wouldhave swept away all the governments concerned with it.” Though
India has experienced plenty of droughts and food shortages since
independence, it has suffered no tragedy on a scale to compare
with those of the late 19th and early 20th centuries.
If the Raj was indifferent as to the human effects of failed mon-
soons, though, it did exhibit an interest in the failures’ causes. In
the early 20th century Gilbert Walker, a brilliant Cambridge math-
ematician who became director of the India Meteorological De-
partment Mr Rajeevan now runs, set his large staff of Indian “com-
puters” to analysing weather data from around the world in search
of patterns. His breakthrough came when he perceived back-and-
forths even grander than that of the winds over the Indian Ocean—
co-ordinated changes in pressure in places many thousands of ki-
lometres apart which he called “world weather”.ENSO it goes
One of these features was the “Southern oscillation”. The usual
pattern of air pressure over the Pacific features high pressure over
Tahiti and low pressure over Darwin, in northern Australia. This
dispensation helps drive the trade winds westward the better to
feed the monsoon as the intertropical convergence zone sweeps
north over India. But a few times a decade a reversal takes place;
the pressure that was up goes down, and that which was down goes
up. Low pressure over Tahiti and high pressure over Darwin dis-
rupts the trade winds. The South Asian monsoon weakens.
Walker guessed that the flipping back and forth had to do with
“variations in activity of the general oceanic circulation”; but he
did not know what they were, and the atmospheric correlations,
though real, proved insufficient to the task of improving forecasts
of the monsoon. The rest of the puzzle was solved by Jacob
Bjerknes, a Norwegian at the University of California, Los Angeles,
in 1969. In the tropical Pacific the eastern waters, off South Ameri-
ca, tend to be cooler than the western ones. Periodically, though,
the waters of the east warm while those of the west get cooler. It is
this which causes Walker’s seesaw to tip. But the atmosphere in its
turn influences the ocean. The strength of the easterly winds in the
Pacific is one of the factors that governs distribution of warmth be-
tween the east and west. The winds and the oceans operate as a
“coupled system”, with heat and momentum shifting from one to
the other and back again.
This coupled system has, since Bjerknes, been known as enso:
en for El Niño, the name that Peruvians give to warm waters
around Christmas time; sofor the Southern oscillation. There are
other regular oscillations in the planet’s climate, but ensois by far
the most important one. When ensoshifts in the warm-water-off-
Peru direction known as its positive phase—as it did, though not
very strongly, this past winter—warmth stored in the waters of the
Pacific flows into the atmosphere, warming the whole globe. The
changes are felt not just in the Pacific and India, but around the
tropics and to some extent beyond. When ensois in its positive
phase, drought can be expected in parts of southern Africa and
eastern Brazil, too, while the southern United States can expect
things to be wet. In the negative phase—“La Niña”—the situation
is largely reversed.
The advent of computerised global-climate models capable of
capturing the effects of far-flung changes in sea-surface tempera-
ture at a reasonable level of detail has in the past decade given
Walker’s heirs more confidence in predicting the South Asian
monsoon’s relative strength. It has also underscored the complex-
ity of the climate system and its interactions with human history.
It is now clear that the failures of the monsoon which the British
exacerbated in the late 19th century were due to very powerful “su-
per El Niños”. Some climate models suggest that these will occur
more often in a warming world. Others, though, disagree. Climate
modelling has improved understanding of the monsoon from year
to year. But if you take the models which best capture the effects of
ensoin the 20th century and ask what they have to say about how
it will work in the hotter 21st century, you find no consensus. 7The sins of starvation wages