Unsustainable population rise is unstoppable, scientists warn

Not even a global one-child policy or a devastating third world war would reduce the human population to sustainable levels, a study has found.

Blue & Green Tomorrow is currently running a crowdfunder to ensure its survival. Please pledge.

The paper, published in the Proceedings of the National Academy of Sciences, concludes that population controls or a global disaster cannot stop the global population reaching 10 billion or more by 2100.

A conflict on the scale of the first two world wars would barely register a blip on the population trajectory, while restrictions on the numbers of children a family may have – similar to China’s one-child policy – would not have an effect until the next century. 

This means a population boom that could reach as high as 12 billion is already “virtually locked in”, the study’s authors warn, meaning there is no “quick fix” to the global sustainability crisis.

Instead, they say the world must focus on policies and technologies that reduce the rising consumption of natural resources and improve recycling rates, if it is to prevent severe shortages and runaway climate change.

“Global population has risen so fast over the past century that roughly 14% of all the human beings that have ever existed are still alive today — that’s a sobering statistic,” explained study author Prof Corey Bradshaw, of the University of Adelaide’s Environment Institute.

“Even a world-wide one-child policy like China’s, implemented over the coming century, or catastrophic mortality events like global conflict or a disease pandemic, would still likely result in 5-10 billion people by 2100.”

While population growth is often described as “the elephant in the room” in discussions about environmental sustainability, the findings suggest that reducing consumption and increasing the global supply of food, water and renewable energy should remain the priority. 

With the population on course to reach 9 billion by the mid-century and with a rapidly expanding global middle class, experts estimate that it would take 1.5 Earths to provide enough renewable ecological resources to meet current demand. 

An awareness-raising event dubbed Earth Overshoot Day is held each year to mark the day after which humanity has exhausted its annual resource budget. This year, Earth Overshoot Day fell on August 19. The year before it fell on August 20, while in 1993, it fell on October 21.

However, alongside a reduction of consumption, the authors of the new study argue that considered attempts to reduce birth rates may have a positive impact in the long term.

“Our work reveals that effective family planning and reproduction education worldwide have great potential to constrain the size of the human population and alleviate pressure on resource availability over the longer term,” said Prof Barry Brook, now of the University of Tasmania.

“Our great-great-great-great grandchildren might ultimately benefit from such planning, but people alive today will not.”

Photo: Scott Cresswell via Flickr

Further reading:

World population expected to grow to 11bn in 2100

Earth Overshoot Day: planet is now in ‘ecological deficit’

World’s wildlife declined by 50% in 40 years

Climate change will trigger global food crisis, says World Bank official

We need three more planets to sustain human life, says NASA scientist