Johan Rockström says humanity has already raced past four of the nine boundaries keeping our planet hospitable to modern life. Writer John Carey digs into the “planetary boundary” theory — and why Rockström says his isn’t, actually, a doomsday message.We’ve been lucky, we humans: For many millennia, we’ve been on a pretty stable — and resilient — planet. As our civilizations developed, we’ve transformed the landscape by cutting down forests and growing crops. We’ve created pollution, and driven plants and animals extinct. Yet our planet has kept spinning along, supporting us, more or less stable and in balance. Going forward, scientists have recently proposed, all we need to do is stay within some limits, nine upper boundaries for bad behavior.
But of course, being human, we haven’t.
In a startling January 2015 paper in Science, Johan Rockström says humanity has already raced past four of the nine boundaries keeping our planet hospitable to modern life. The climate is changing too quickly, species are going extinct too fast, we’re adding too many nutrients like nitrogen to our ecosystems, and we keep on cutting down forests and other natural lands. And we’re inching towards crossing the remaining five boundaries (see image).
Rockström (TED Talk: Let the environment guide our development) is the executive director of the Stockholm Resilience Centre, and his paper is co-authored by 17 colleagues. “The planet has been our best friend by buffering our actions and showing its resilience,” Rockström says. “But for the first time ever, we might shift the planet from friend to foe.”
Rockström conceived of the idea of planetary boundaries back in 2007, and published his first landmark paper on the topic in 2009. The new paper digs far deeper. A key underlying assumption is that the extraordinary climate stability of the Holocene Epoch, which began when the last Ice Age ended 11,000 years ago, has been crucial to human development. This period of planetary calm enabled our ancestors to emerge from their Paleolithic caves to cultivate wheat, domesticate animals, and launch industrial and communications revolutions. As a result, the world now has 7.2 billion people—and almost that many cell phones.
Download and print The Planetary Boundaries