Roughly 10,000 years ago, the great sheets of ice that had covered much of the planet receded, triggering a wave of extinctions, ecological changes and, ultimately, the rise of human civilization. All those changes came about as roughly 30 percent of the planet's surface went from ice-covered to ice-free.
Since then, humans have transformed roughly 43 percent of the planet's surface to suit our need for food and shelter. Think: agriculture and cities.
Now scientists suggest that our ongoing population growth, natural resource consumption and climate-changing fossil fuel burning may precipitate a global environmental shift like the end of the last Ice Age. Such a "critical transition" or "tipping point" could bring about an entirely different planet, from a biological perspective. The paper is in the journal Nature. (Scientific American is part of Nature Publishing Group.)
The scientists suggest that we strive to restrain our influence on planet-wide alteration. But they also say we should prepare for the consequences, whether they be a mass extinction event or the collapse of critical ecosystem services like clean water or fertile soils. They also suggest that we might want to look into methods to forecast when such a tipping point might occur. If it hasn't already.
[The above text is an exact transcript of this podcast.]