Having 7 billion human beings on the planet, living as we do, is straining the planet’s natural resources. The destruction of the natural world from human activity presents an “ominous picture”, as the UN put it. And the global population is expected to keep growing for most of this century. In 2017 the UN predicted the world would have 9.8 billion humans by 2050, and 11.2 billion by 2100. Global population growth is about increased longevity as well as the birth rate. Credit:Tomohiro Ohsumi Do I think it’s important to reverse this trend? Yes. But how? I hope my readers weren’t suggesting we should make like a Batman villain and unleash a deadly epidemic. That would be a pyrrhic victory; imagine the misery as our friends and relatives are decimated and survivors flee the cities. Plus, if we didn’t alter the underlying trend, we would be back where we started within decades.

The population is growing because people are living longer and the birth rate in most of the world remains higher than the replacement rate of two children per couple. China famously got a grip on its population by imposing a one-child policy but that’s an authoritarian option not easily replicated. If the experience of the developed world is a guide, we achieve lower birth rates voluntarily as a result of three things: higher living standards including health care; the education and economic participation of women and girls; and ready access to birth control. While charities such as Room to Read are tackling the education gap, many others oppose family planning services, especially if they offer abortion. The problem with any social change is it’s a slow burn – lower birth rates develop over decades and the effect on the overall population is felt decades after that.

We have about 12 years to avoid the worst effects of climate change and prevent a mass extinction event. We should certainly work on the long-term population trend, but that doesn’t let us off the hook for reducing consumption. What about Australia's population? The main driver of growth is immigration and, to a lesser extent, longevity. Loading There are many voters who want to reduce immigration and sometimes environmental sustainability is given as the reason. While large, Australia has delicate ecology and a scarcity of water and fertile land. People feel our cities are becoming overcrowded and governments find it hard to keep pace with infrastructure. And some say the economic benefits of immigration are illusory, as it grows the economy but not on a per capita basis.

It’s hard to have a proper debate about population in Australia, because it’s inevitably about immigration and then it usually becomes about race and racism. In theory we should be able to talk about population separately, but in practice we’re not good at it. “I can't think of a single discussion with a group of Australians in my entire career about population that wasn't about race,” says social researcher Rebecca Huntley, who specialises in qualitative studies in small focus groups. No wonder many people shy away from the topic. Yet there is nothing magical about our current immigration intake. It’s entirely possible to argue for a higher or lower intake based on rational, non-racist reasons. So what happens if you look at Australia’s population purely through the environmental prism?

The endangered mahogany glider in northern Queensland. Credit:AAP/Far North Telecommunication Service The truth is Australia’s environmental record has very little to do with our population. We only have 25 million people but we have an appalling record on land clearing and extinction since 1788. Loading Yet Wilderness Society federal policy director Tim Beshara says most of our land clearing and water usage is for beef cattle, grain growing and cotton crops. These commodities are mostly exported so Australia’s population is barely relevant. Same with mining. There is pressure on wildlife around our cities and we need planning policies that keep urban sprawl in check and incorporate trees and green space into the city. Yet Beshara says most endangered species are in completely different areas, such as the desert or vast expanses of northern Australia where the legacy of invasive species is taking a toll.