Debate continues to rage over how much of a population the earth can sustain

Experts have different views on how much of a population rise the earth can sustain, but many believe the crunch is approaching

PUBLISHED : Sunday, 25 May, 2014, 4:25am
UPDATED : Sunday, 25 May, 2014, 4:25am

After I sent my US biologist friend Dr James Lazell a recent column on global warming, he also suggested I write about human overpopulation. This seems a thornier issue for conservation than even climate change, as debates can feature religion, racism, eugenics and genocide.

Yet overpopulation has long been a concern to me, and seems timely in Hong Kong given arguments raging over mainland tourists dubbed "locusts", housing threats to country parks and outrageous plans such as building artificial islands for shopping malls, housing and a giant incinerator.

"Great!!" Lazell replied on learning I would indeed cover overpopulation. "Remember my favourite stat: Americans are 320 million people and consume 40 per cent of all annually available resources. 320 is to 40 as X is to 100 ... Fewer than one billion people can live on earth at the American standard of living ... Overpopulation is the Mother of All our Problems; all-out-War will come..."

Yikes, you might think. That wasn't the feel-good banter I hope for in a Sunday column.

Yet Lazell is far from the only person to make doom-laden warnings about humanity's burgeoning numbers. One of the best known was English clergyman and scholar Thomas Robert Malthus, who in 1798 published An Essay on the Principle of Population, with pronouncements including: "The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race."

More recently, in 1968, The Population Bomb by Stanford University professor Paul Ehrlich and wife Anna warned of massive famines during the 1970s.

These dire predictions have so far proven wrong, with the human population more than tripling from around a billion in 1798 to over 3.5 billion as The Population Bomb appeared, and more than doubling in the years since, to reach seven billion and growing today.

To some people, this shows Malthus and the Erhlichs were just plain wrong. Others - like Lazell - instead believe that in time they will be proved right, and it is only unforeseen events like the industrial revolution and the "green revolution" that helped feed many more people and stave off catastrophe.

Economist Julian Simon was among the strongest proponents of the idea that humanity was nowhere close to approaching its limits. He famously won a wager with Paul Ehrlich that the prices of five metals would fall during the 10-year period from 1980. Yet he would have lost the bet in each decade since, and his astonishingly rosy-tinted view of the future was reflected in an assertion made in 1994, when he wrote that we have "the technology to feed, clothe and supply energy to an ever-growing population for the next seven billion years." This was ridiculed, including by Paul and Anna Ehrlich, who noted that after 6,000 years at 1994 growth rates, the mass of the human population would equal the mass of the universe.

The global conservation body WWF publishes an annual report about the human footprint on the planet, a measure of how much we are using the earth's natural resources. Last year, the report found that globally, it would take 1.5 earths to produce all the renewable resources we use. Hong Kong people are living even further beyond earth's limits, with 2.6 earths needed if everyone lived like Hongkongers (surely a substantial underestimate). In tandem with the report, WWF-Hong Kong gave recommendations for how to live more sustainably, such as taking public transport and buying efficient appliances. But one recommendation was notably absent: "Have fewer children."

In researching this column, I learned that WWF does not have a policy on population, and wondered if this is because the issue is too controversial. Political leanings and religious beliefs - like the absurd notion we should "go forth and multiply" - help dissuade discussion. But even some conservationists recoil at the notion that overpopulation is a problem. British environmental writer George Monbiot wrote an acerbic article with the claim: "Most of those who are obsessed with population growth are post-reproductive wealthy white men." Instead, he said the real troubles stem from consumption by rich people like owners of superyachts.

This surely means that overpopulation woes include there being too many rich people; it is more than simply a numbers game. And as Jared Diamond shows in his book Collapse, human societies were failing from unsustainable growth and unsound policies long before there were superyachts. The Angkor complex and Easter Island are among places where he believes civilisations thrived, then failed by overstraining environments.

Here in Hong Kong, we're all too familiar with air pollution, and there are concerns over water supplies. Original forests are long gone, much as primary forests are dwindling worldwide. The world's fisheries are depleted, soils are thinning and greenhouse gas emissions from human activities are transforming climate systems and raising sea levels.

Overpopulation is an issue with no easy solution, though education and access to contraception are important: every sperm is not sacred! It is not something to be downplayed, with the foolish belief that we can always rely on our ingenuity to avoid calamity.

This latter point was recognised by Norman Borlaug, a pivotal figure in the green revolution. In his 1970 Nobel acceptance speech, he said: "There can be no permanent progress in the battle against hunger until the agencies that fight for increased food production and those that fight for population control unite in a common effort."

As yet, there is no such unity. Among indicators of the ballooning importance of overpopulation, the Los Angeles Times recently quoted Hans-Joachim Braun, Borlaug's successor at the International Maize and Wheat Improvement Centre in Texcoco, Mexico, as saying: "In the next 50 years, we will need to produce as much food as has been consumed over our entire human history." This comes as global crop yields are reaching a plateau and amid concerns over supplies of phosphorus needed for fertilisers.

British wildlife television presenter David Attenborough last year belied his genial disposition by saying "we are a plague on earth". Though not warning of war like Lazell, he too had a stark view of the situation: "Either we limit our population growth or the natural world will do it for us."

Martin Williams is a Hong Kong-based writer specialising in conservation and the environment