The human race's profligate use of fertilisers may be about to breach "planetary boundaries" and render our planet unable to support civilisation, an American limnologist has claimed.
“We’re running up to and beyond the biophysical boundaries that enable human civilisation as we know it to exist,” says Stephen Carpenter, director of the Center for Limnology at the University of Wisconsin-Madison. Professor Carpenter originally trained in biology and botany, but is nowadays engaged in limnology, the study of inland waters.
According to the prof, until a point around a hundred years ago, the planetary ecosystem had been stable for thousands of years - throughout the Holocene era. In his view, this was a great thing for the development of human civilisation. "Everything important to civilisation," he contends, took place prior to 1914: he specifically mentions "the development of agriculture, the rise and fall of the Roman Empire and the Industrial Revolution".
Carpenter and colleagues from around the world have been working on a report into the various way that humanity may be rendering its home world uninhabitable. The report, Planetary Boundaries, is published in the noted boffinry mag Science and is to be discussed next week at the World Economic Forum in Davos.
The report does of course mention the looming possible menace of carbon-driven global warming and associated climate change, sea level rise etc. Likewise it also touches on another trendy disaster threat, that of biodiversity loss. But in Carpenter's view this is comparatively penny-ante stuff.
“We’ve changed nitrogen and phosphorus cycles vastly more than any other element,” says the prof. “(The increase) is on the order of 200 to 300 percent. In contrast, carbon has only been increased 10 to 20 percent and look at all the uproar that has caused in the climate.”
Artificial phosphorus and nitrogen aren't just scattered about for fun, of course. They're used to fertilise crops, as part of the intensive agriculture which has meant that relatively few people have trouble getting enough to eat despite the huge increases in the global population over recent decades.
Carpenter believes, however, that Western farmers use way more fertiliser than they actually need to, while those in Africa can't get any - and thus, sometimes, can't produce enough food.
“We’ve got certain parts of the world that are overpolluted with nitrogen and phosphorus, and others where people don’t even have enough to grow the food they need," he says.
In the prof's view it's extremely urgent for the human race to cut down on fertiliser over-use, as this could knacker the eco-system to such an extent that it could no longer support civilisation and surviving humans would have to return to life as hunter-gatherers.
“It might be possible for human civilisation to live outside Holocene conditions, but it’s never been tried before,” Carpenter says. “We know civilisation can make it in Holocene conditions, so it seems wise to try to maintain them.” ®