In 1998, on the 200th anniversary of the book’s publishing, Gary Gardner and a group of colleagues at the Worldwatch Institute released a new vision of the Malthusian theory in a book entitled "Beyond Malthus: Nineteen dimensions of the population challenge." James Stewart, KPMG's Global Infrastructure Chairman, recently caught up with Gary in the Sierra Nevada Mountains to find out what has changed over the past 200 years and what we can learn from Malthus going forward.

James Stewart (JS): While we all learned about Malthus in school, many would suggest that he was wrong or that his theory on population is no longer relevant. Why was it important for Worldwatch to revisit the theory on its 200th anniversary?

Gary Gardner (GG): It’s certainly true that many of Malthus’ projections never came to pass and, as a result, there is significant skepticism about his view. But from our perspective, there are plenty of reasons to take a fresh look at his argument through the lens of not just agricultural output and resources, but also a wide range of other natural resources from a per capita perspective. So, for example, we wanted to see if there was enough oil, water, energy or minerals to sustain a growing population; to apply the Malthusian premise to a wide range of resources that we consider vital in the modern era.

JS: Before we look ahead, let’s look back. Why exactly did Malthus’ projections never materialize? Was his theory faulty?

GG: I don’t think his theory was faulty: population and resource scarcity are certainly intertwined. But there were a few factors that Malthus either underestimated or didn’t know about. He could never have foreseen, for example, how the application of technology – everything from irrigation and mechanization through to genetically enhanced seeds – would exponentially improve the bounty of agriculture.

Malthus also assumed that human nature would drive people to have as many children as possible – a flawed premise that was quickly proven wrong; as economic and educational status increase, and as women gain better access to healthcare and jobs, family sizes actually contract.

But the relationship between population and resources does matter and we can’t simply assume that technology will always provide that silver bullet. So in that sense, Malthus may have just been ahead of his time.

JS: Is there something that governments can be doing to ensure that population growth does not outstrip our resource capacity over the next 200 years?

GG: There are really two sides to that. On the one hand, it’s clear that enhancing the status of women, in particular, so that they are more empowered economically and better able to make choices about family size is key to reducing fertility and overall birth rates. And clearly there are a number of policy levers that governments can pull to facilitate that.

But on the other hand, we also need to recognize that there is only so much that reducing fertility rates can achieve; the global population is likely to grow in the decades ahead no matter what we do. So governments need to start thinking about how they manage a particular population size and how they can achieve efficiencies in their resource use to fit the needs of that future population.

JS: Infrastructure can play a key role in achieving those types of efficiencies, right?

GG: Absolutely. It’s all about increasing the efficiency of water, of energy, of raw materials, of production capability – of any resource really; building a circular economy where all the resources used are either recycled or reused to the maximum extent possible. If we can make infrastructure deliver and use resources more efficiently, then we can stretch those saved resources farther to support a larger population.

As most infrastructure designers know well enough, population density is also essential to achieving resource efficiencies for individual assets and systems. Cities that offer alternative forms of transit and efficient public transit, for example, will use far fewer resources per capita than those created around private transport. Ultimately, the way a city is planned and the density that is encouraged will be very important to our ability to manage into the future.

JS: Are there specific resources that you are worried about?

GG: I think water scarcity is one of the biggest threats facing the world population today. Recent projections show that the numbers of people living in absolutely water scarce conditions will more than triple to 1.8 billion in the next decade. Less drastic water scarcity will impact large parts of the world, both developed and developing. And this is having a massive influence on potential food scarcity.

Already, around 16 percent of the world’s food is imported from other countries, in many cases because water scarcity has made it more economical to import food than to use domestic water to grow it. So we are now starting to see countries – particularly in the Middle East and Asia - import water ‘virtually’, that is in the form of crops and other imports. In Jordan, for example, virtual water amounts to five times the renewable water endowment in the country.

JS: Looking back over the 16 years since you wrote your book, has anything changed with regard to population and resource use?

GG: I think the biggest change over the past two decades has been the increasing urgency of the sustainability challenge. In 1998, we decried the fact that countries were at threat of losing their self-sufficiency in food. Since then we’ve seen the situation change drastically: governments are now shifting food production and agricultural policy to rely on a mix of imported and domestically grown foods.

Energy availability has also moved up the agenda since we first wrote the book. Today it takes more and more energy to get to key resources, including energy itself. Oil wells are drilled in the harder-to-reach deep sea; mining companies dig deeper and deeper, often for diminishing quality returns; and fishing fleets have to go further to find their catch. All of this requires more and more energy at a time where it is not entirely clear that more energy is going to be available. It’s all brought a greater sense of urgency to the situation.

JS: What advice would you give infrastructure players and governments based on your experience?

GG: I would suggest that societies need to do a better job of thinking long term, a skill that comes naturally to infrastructure planners, and to do so in a green way. For example, a power plant built today will be online for decades. Is it really smart to lock ourselves into decades' more commitment to dirty energy, by building plants powered by fossil fuels? Infrastructure providers can have huge influence in creating sustainable societies, through their capacity to conceptualize, build and implement greener infrastructure solutions for the long haul.

I also believe that we need to put more emphasis on projects that provide broader socio-economic security – economic employment opportunities, health care, education and so on – which, ultimately, provides greater sustainability and stability for populations, governments and economies. Infrastructure can help here as well. The World Health Organization recently increased sharply its estimate of the number of people worldwide who die from air pollution, to seven million annually. Roughly half of these deaths are from outdoor pollution from automobiles and factories, while the remainder is caused by indoor pollution such as burning wood or dung for heating or cooking. There are huge infrastructure opportunities in either case to reduce air pollution and the deaths they cause, and in the long run, to stabilize populations.