Coutesy: BBC - Gaia Vince
Some 10,000 years ago, at the beginning of the
Holocene geological age,
there were only around five million of us on the planet. Although
humans had a significant impact on the natural world – by using fires to
clear forestry or hunting large mammals to extinction – their effects
were localised.
Boy, have things changed. In 1900, there were 1.6
billion of us; by 2000 the global population had shot up to 6.1 billion.
Last year, we passed the
seven billion mark, and best estimates have us reaching the nine billion mark before 2050.
The
sheer number of people has profoundly changed the global landscape, as
we convert vast tracts of wild vegetation to agricultural or grazing
areas, for example. Fishing on an industrial scale to provide for
billions has dramatically altered marine diversity. Individual farmers
breeding livestock or keeping chickens, when multiplied by millions,
have caused biodiversity changes in which more than 90% of the weight of
all terrestrial vertebrates is now made up of humans and the animals
we've domesticated. The quest for resources to supply us all with
materials and the trappings of life has depleted the forests, polluted
rivers and soils and even carved the tops of mountains. And the fuels
used by each of us for energy have produced combined emissions that are
already altering the planet's climate.
By 2050, it is estimated that we could triple our resource consumption to a whopping
140 billion tonnes of minerals, ores, fossil fuels and biomass per year. Our food requirement alone is expected to double by then.
Is
our ever-increasing human population propelling us to our doom? Is
there a limit to how many people can be sustained on a finite planet –
and, if so, have we already passed it?
Grim predictions
It’s
not the first time we’ve been presented with this doomsday scenario.
More than two centuries ago, when the global population was around an
estimated one billion, the British social economist
Thomas Malthus
issued dire warnings about the risk of population exceeding resource
limits. In 1798, he advocated limiting family size and postponing
marriage. (As one of seven children, he practiced what he preached by
only having three of his own.)
Since Malthus, there has been no
shortage of economists, environmentalists and demographers predicting
humanity's collapse through famine, wars and epidemics, if we don't
check our population. Some environmentalists even go as far as to say it
is morally wrong to have children at all.
So far, the doomsayers
have been proved wrong: tragedy has been averted through better
technologies, the invention of artificial fertilisers, improved
medicines and other rescuing remedies. Indeed, there are some examples
of where population increase has led to resources being better conserved
and managed. For example,
Machakos in Kenya,
whose population rose to 250,000 – with accompanying resource
over-exploitation, denuded hillsides and soil erosion – actually
improved when its population rose still further. The extra labour
available meant hillsides could be restored and soil erosion tempered,
and Machakos is now home to 1.5 million people.
However, whether
this improvement can be solely attributed to the increase in population,
and whether it can be replicated elsewhere, remains debatable. Examples
like Machakos are few and far between – outweighed by the far greater
number of societies that have collapsed due to unsustainable resource
use, driven by overpopulation.
