GOOD morning. I would like to start by saying how pleased I am to see so many
of you at the Edinburgh Science Festival in this first year of the 22nd century.
My role today is to discuss the Great Depopulation that took place last century,
leaving us with today’s global total of around two billion people—about
what we had back in 1950.
It was Thomas Malthus who, in the 18th century, first suggested that a
growing population might outstrip its food supply. It didn’t happen in Malthus’s
day, of course, or for the next two centuries. Even when the rate of growth of
the world population hit its peak in the 1960s and 1970s, scientists kept crop
yields ahead of demand, thanks to the “Green Revolution”, which eventually
introduced high-yielding crops, chemical fertilisers and mechanised agriculture
to every region capable of using them. There were sporadic famines, but they
were triggered by uneven distribution of wealth.
By the 1990s it was apparent that population growth had slowed, and in 1994
demographers predicted that numbers would stabilise at 9 billion by 2050. Many
people stopped worrying about a population crisis.
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As we all now know, the demographers were half right. The population did
reach 9 billion. But it didn’t stay there long. By the 2050s, food production
was declining sharply, and in many places, high-yield agriculture collapsed
completely. This led to the great famines. Meanwhile, population density
triggered two other agents of decline: the great migrations and the plagues.
World population plummeted.
What happened to turn the sunny forecasts of the 1990s into the horror that
followed? In retrospect, it seems obvious: the Earth could feed 9 billion
people—but only for a short time. The environmental cost was too high to
be sustainable. To put it simply, we ran out of soil and we ran out of
water.
We destroyed the soil by using harmful farming technologies to wring more
crops out of the land. Chemical fertilisers could replace the mineral nutrients
taken by the plants, but couldn’t restore the soil’s fine microstructure.
Excessive ploughing, and compaction by heavy farm machinery left the soil prone
to erosion. It simply blew and washed away.
This process was well under way by the late 20th century. Indeed, in 2001 a
report by the World Resources Institute, an American environmental think tank,
found that soil and water degradation were already decreasing yields on 16 per
cent of the world’s agricultural land.
We knew the danger, but in many places little was done to slow soil
degradation. This was partly because research on soil structure dropped to
almost nothing when most agricultural research was privatised at the turn of the
century. But it was mainly because demand for food was increasing, and it proved
hard to move away from the old technology while maintaining yields.
Eventually, soil degradation helped to halve yields across Australia, eastern
Asia and Europe. The great dust storms of the 2050s whipped millions of tonnes
of irreplaceable topsoil off the land and brought famine even to wealthy
nations.
North America was spared this problem. Ploughing had always served mainly to
control weeds, and North American farmers replaced it with weedkiller after the
introduction of genetically engineered, herbicide-tolerant crops. Europe
rejected genetically engineered crops until 2035, but by then it was too
late—crop varieties engineered for North America could not thrive in its
degraded soils.
But North America had other problems, primarily water shortages. Many
irrigated regions were using up ancient, underground deposits of water, while
others drained rain-fed aquifers faster than they were being replenished. Many
parts of the world faced the same problem. Even in 2000, the fertile Punjab was
pumping irrigation water from aquifers twice as fast as rainfall could replace
it. By 2020, these had nearly run dry, as had those beneath the breadbasket
region of northern China. The Ogallala aquifer in western North America
collapsed soon after. In these regions, farmers had to go back to relying on
rainfall, just when climate change began to make that less predictable.
Even where water supplies did not depend on aquifers, the swelling population
pushed demand for drinking and irrigation water beyond supply. In 2001, the
populations of what were then Egypt, Sudan and Ethiopia were on course to double
within 50 years. Ethiopia had used irrigation to intensify its highland
agriculture, but it needed a more reliable supply of water. So in 2026, it began
damming the Blue Nile.
Egypt, which received 80 per cent of its water from the river, reacted by
destroying the dam that year and, after a bloody war, annexed the entire Blue
Nile catchment. Similar pressures, and the exhaustion of the Negev aquifer, led
Israel to take control of the Jordan in 2029, while Iraq bombed Turkey’s Ataturk
Dam on the Euphrates two years later. These are generally considered the first
of the continuing water wars.
Food from the oceans plummeted, too. Astonishing as it seems, a hundred years
ago wild fish from the seas provided protein for billions of people. But we took
fish out of the sea faster than they could reproduce, and by 2020 many major
stocks had collapsed. A global ban on fishing might have allowed some to recover
even then, but the demand for protein was so great that no one could muster the
political will. Those once rich ocean areas are now dominated by species that
provide little protein. In most cases this change is expected to be
permanent.
Even as the fish harvest dwindled, urban prosperity increased, notably in
East Asia. This led to skyrocketing demand for milk and meat. Thirsty farm
animals increased the demand for water. But their major impact was on grain
reserves: it takes 3 kilograms of grain to produce 1 kilogram of meat. So long
as meat eaters could pay, the huge Chinese pig conglomerates, for instance,
could easily outbid poor people for grain on the global market. Prices trebled
in the 2020s, starting a wave of famine.
What were the scientists doing all this time? After all, by the turn of the
millennium many of the threats to the global food supply had been predicted.
Some fields were already nearing the limit of what they could grow. The high
yields achieved by the Green Revolution came from crop varieties that put more
of the carbon they fixed through photosynthesis into grain, and less into stalks
and leaves. By 2000 we had pushed the plants to their limits. And in places such
as the rice fields of Japan, we were already pouring on as much nitrogen
fertiliser as the plants could handle.
Still, there was room to improve yields in much of the world, and optimists
proposed numerous technical fixes, such as better crop varieties and farming
technologies. In many cases people did develop fixes. But often by the time
these were ready, the problem itself had changed. What defeated us, I think, was
the complexity of the problems and the speed at which they changed. The
goalposts kept moving.
The greatest challenge, of course, has been climate change. As we know, it is
now too warm or wet or dry to grow wheat in most places where it thrived a
century ago. Where there is still enough soil and water, varieties of maize and
sorghum deliver substantial yields—but it took a while to develop
them.
Likewise, many of us would not be here without the genetically engineered
high-yield barley the Russians and Canadians now grow in the Arctic. But it took
two decades of research to develop varieties that could thrive on melted
permafrost.
Changing climates also meant changing pests. After the north Chinese aquifer
ran dry, plant breeders engineered a dry-land variety of wheat. But as the
region warmed up, exotic insect pests and diseases moved north. The new wheat,
designed to cope with the old pests, proved susceptible to the newcomers.
Breeders introduced variety after variety to respond to each new problem, but
never quite kept up.
This frenzy of crop development brought its own problems, as breeders tried
to work a few high-yielding characteristics into all regional varieties. By the
time fulminating wheat bunt broke out in 2047, almost every strain of wheat in
the world carried the same set of genes involved in photosynthesis.
Unfortunately, the bunt fungus attacked the very characteristics coded for by
those genes. In 2053, the disease wiped out nearly all the world’s wheat crop.
Global wheat production still hasn’t recovered.
The increasing globalisation of trade cushioned the initial regional food
shortages. The Rio Plus Ten global conference of 2002 famously predicted that
all famine would cease, as production shortfalls could be met by imports. But
this missed the point that increasing global trade was already spreading
invasive, alien insects, plants and microbes throughout the world. No longer
held in check by natural predators, these visitors turned into pests. Worse,
these new pests, like the old ones, quickly became resistant to the chemicals
farmers used to control them. The big corporations had a hard time finding new
pesticides.
In the face of all this, many farmers joined a worldwide exodus and sold
their land to the expanding cities. They swelled the numbers of unemployed in
these conurbations, a process that was already under way in the 1990s in
megacities such as Shanghai. The hungry, out-of-work urban hordes caused
political upheaval nearly everywhere, which in turn triggered huge migrations of
people seeking a living or escaping violence. The struggle for costly food,
clean water and healthcare increased tensions between rich and
poor—especially as TV and the Internet constantly reminded the poor of
what they did not have.
The sheer size of some cities created its own problems. Getting massive
quantities of food in, and waste out, became harder and harder. When either
process faltered, even briefly, people died because of violence, efforts to flee
or plain starvation.
Worst of all, as the megacities mushroomed, the densely packed masses of
hungry people became a perfect breeding ground for epidemics. Simple
overcrowding spread diseases such as leprosy, which re-established itself in
Europe in the 2030s. As cities outgrew their sewerage and drinking-water
systems, the decline in hygiene ushered in killers such as dysentery. Warming,
trash-strewn cities helped launch the bubonic plague pandemic of 2047. Typhus
returned worldwide in 2056. Overburdened medical services couldn’t deal properly
with any of the diseases, especially after the widespread emergence of
drug-resistant bacteria made antibiotics redundant.
The vast numbers of displaced people were also a factor in the spread of
disease, including the re-invasion of North America by malaria—a process
aided by warmer winters. In Africa and South America, ever-expanding human
settlements invaded new territories, notably deserts and tropical forests. This
led to novel encounters with local fauna, and the emergence of at least two
dozen new diseases, including monkeypox and the haemorrhagic virus that caused
Europe’s worst disease mortality since the Middle Ages.
Agriculture gave us yet more plagues. Animal diseases that attack humans
flourished—the Flanders flu, which emerged from pigs in 2018, was the
first of five flu pandemics last century. But new ones also emerged in giant,
crowded livestock barns, helped by the global movement of animal produce.
Human-adapted foot and mouth virus (HAFMV) emerged in Taiwan in 2065, and spread
uncontrollably.
Safety precautions could have prevented the emergence of these infections.
But as both demand and the cost of food and water soared, hard-pressed farmers
could not afford them. At the time of the first prion disease, for instance,
Europe could afford to incinerate more than a million cattle that were mainly
infected only in their brains. The thought is shocking today.
Famine, war and pestilence have always figured in human history, but their
fury has redoubled over much of the past century. The breakdown in our natural
support systems of soil, water, climate and crops happened too fast for us to
cope.
Could we have avoided any of this misery? I think so, if we had acted early.
We did once have the technology—or the ability to develop it—that
would have fed 9 billion, kept them free from disease and perhaps living in
peace. But we never stayed organised socially, politically or economically for
long enough to deliver the solutions when and where they were needed.
Sometimes I wonder whether it would have been different if, when industry
globalised at the start of the millennium, political power had globalised too. I
know the idea of global government is a heresy. But so many of our crises were
outside the realm of corporate concern, and beyond the power of national and
regional governments. A global authority might have been able to monitor and
perhaps stem the spread of human, animal and crop diseases. It might have
launched earlier research into foreseeable dangers, such as a wheat crop that
depended on only a few proprietary genes. It might have provided jobs in time to
prevent some of the mass migrations. We who remain can only wonder what would
have happened if it had.