Study Complicates Relationship of Population Growth, Emissions Reduction

Conservation ecologist Corey Bradshaw of the University of Adelaide in South Australia "decided to look into this question of whether trying to reduce the size of the global population would help stave off climate change, the loss of species, and other environmental concerns," writes Chris Mooney of The Washington Post's Wonkblog

The resulting research, just out in the Proceedings of the National Academy of Sciences (PNAS) and co-authored by the University of Adelaide's Barry Brook, seriously challenges the idea that greens ought to be campaigning for population control.

The reason: "(T)he increase in population over the course of the 21st century is 'virtually locked-in'; this means, the authors argue, that population reduction "cannot be argued to be the elephant in the room for immediate environmental sustainability and climate policy."

"No matter what levers you pull, we have such a huge demographic momentum, there’s no way we can rein in the human population fast enough to address sustainability issues in the next century," says Bradshaw.

With only one catastrophic exception, "the result was always the same: We wound up roughly where the U.N. currently projects, or around 10 billion [or 11 billion?] people by 2100," states Bradshaw."

The exception: "6 billion people suddenly killed in a catastrophic war or pandemic; or a sudden, draconian and globally enforced one-child policy -- dramatically changed the trajectory of population growth by 2100," writes Mooney.

Four years earlier, PNAS published a study that appeared to come to a different conclusion on population growth and emissions reduction, posted here. However, for those preaching the virtues of reduced population growth, the report indicates that their findings apply mainly to developing nations as "industrialised countries could see emissions fall by about 20% as a result of ageing populations," according to the BBC.

And even in that 2010 study, the authors warn, "If global population growth slows down, it is not going to solve the climate problem," said lead author Brian O'Neill, a scientist at the US National Center for Atmospheric Research.