This post was first published here on November 15, 2022
According to the UN, the world’s population of humans reached eight billion today. When America was founded, the world’s population was under 800 million. In 1900, it was only 1.6 billion. When I was born, the world’s population was under three billion. And it’s still growing by 50 or 60 million more people every year, likely to reach or exceed 10 billion in the coming decades.
As populations have risen, there have been some remarkable advances in human well-being. Average income has risen, and average life expectancy is decades longer than a century ago. The fraction of people living in extreme poverty has fallen and global economic activity has soared. But these gains hide continued devastating poverty, widespread hunger, and growing disparities between the mega-rich and the very poor. Equally important, the traditional measures of well-being fail to capture the growing and massive environmental threats that now face us, including widespread species extinction, growing competition for natural resources such as fresh water and minerals, and increasingly severe climate changes. In a real sense, those of us in the wealthier countries of the world have grown rich by plundering the natural capital of a finite world.
The number of people on the planet, along with how much of everything we consume, and how the things we consume are made, lies at the heart of almost every environmental, political, and social challenge. Scientists have taken to calling our current era the “Anthropocene,” an epoch when humans have begun having a clear and significant impact on Earth’s oceans, water, atmosphere, and soils. We’re strip-mining the seas and the land of fish, animals, birds, and insects. We’re leaving behind a geological layer of plastic and waste that future archeologists and geologists will be able to use to date this period in time. And we’re changing our very climate. We’re also falling behind in the struggle to meet current demands for food, water, energy, and minerals. After declining for several decades, global hunger is again on the rise, and the UN estimates that 800 million people go to bed hungry every day . Two billion people – one in four – lack safe drinking water at home . And as human populations have exploded, scientists estimate that world wildlife populations have plummeted, dropping nearly 70 percent between 1970 and 2018 .
British economist Sir Partha Dasgupta and his colleagues describe the modern era as a time when “the biosphere’s goods and services – humanity’s ‘ecological footprint’ – vastly exceeds its ability to supply it on a sustainable basis”. In part, this is due to the sheer number of people, but it is also the result of the massive imbalance in the style and level of consumption between the rich and the poor.
One remarkable day in the future, perhaps in this century, the population of the planet will be smaller than the day before, marking a watershed in human history.
Population growth is slowing in part through improvements in standards of living, expanded educational and employment opportunities for girls and women, better access to contraception, and the empowerment of women to have children by choice. Ultimately, we will have to figure out how to manage the challenges of a declining and aging population, rather than an endlessly rising one. Those challenges include a growing demand for health services and care for the elderly, a shrinking tax base and workforce, and expanding cities. But these problems are manageable: in countries already experiencing a demographic transition, there has been no shortage of workers, rather there has been sustained economic activity and less unemployment. Where health costs are rising, it’s due to expanded and improved services and predatory practices by insurance and drug companies rather than a rise in the proportion of older citizens.
Until the day the curve bends down, however, humanity is in a desperate race to feed, educate, employ, and support however many people the Earth holds, in a fair and equitable manner, and without undermining the very environmental life support systems that sustain us.
Technology can help. Renewable and distributed energy systems offer new hope for meeting growing demands for energy without burning climate-destroying fossil fuels. Better irrigation and water-using technologies and new crop varieties can help us meet our food and water needs without further depleting our rivers and groundwater. Satellites and remote sensing platforms and better communications systems can help prepare and protect populations from increasingly extreme weather.
But technology alone isn’t enough. We need better social and political tools and institutions to tackle the challenges of our growing population and our inequitable distribution and use of resources. We need changes in the consumptive behavior of the rich, changes in diets away from energy-, land-, and water-intensive meats, and a reduction in the throw-away mentality that both consumes unnecessary resources and pollutes our environment. We need to greatly expand voluntary family planning services, which are now severely underfunded and underpromoted. And even as the global population expands, we need to begin planning today for the end of the era of endless growth and the chance for true sustainability.
 Dasgupta, P., Dasgupta, A. & Barrett, S. Population, Ecological Footprint and the Sustainable Development Goals. Environ Resource Econ (2021). https://doi.org/10.1007/s10640-021-00595-5
Dr. Peter Gleick is a leading scientist, innovator, and communicator on global water and climate issues. He co-founded the Pacific Institute in Oakland, one of the most innovative, independent non-governmental organizations addressing the connections between the environment and global sustainability. Dr. Gleick’s work has redefined water from the realm of engineers to the world of sustainability, human rights, and integrated thinking. Gleick pioneered the concept of the “soft path for water,” developed the idea of “peak water,” and has written about the need for a “local water movement.” Among many other honors, Gleick received the prestigious MacArthur “genius” Fellowship, the U.S. Water Prize, and has been named “a visionary on the environment” by the BBC. He was elected in 2006 to the U.S. National Academy of Sciences. In 2018 he was awarded the Carl Sagan Prize for Science Popularization.
Gleick is the author/editor of many scientific papers and books, including The World’s Water series, Bottled and Sold: The Story Behind Our Obsession with Bottled Water (Island Press, Washington), and A 21st Century U.S. Water Policy (Oxford University Press, New York).