Peak Phosphorous

I’ve just become aware of another malady that industrial society has to worry about. Peak phosphorous is probably not on your radar yet, but it could be as big a problem for society as peak oil or climate change.

Phosphorous is an essential element for all life forms. Phosphate is part of the DNA and RNA structure; ADP and ATP are the energy molecules of the cell. The element makes up about 0.1% of the earth’s crust, but in living organisms it concentrates to more than 1% by weight. As an essential element of life, there is phosphorus in the food we eat, and we excrete what we don’t need. And that’s the rub. Industrial societies flush a lot of phosphate down the toilet where it ends up as pollutants in our waterways or as sewage sludge in the landfill. Phosphorous is often a limiting factor for growth, so additions of large amounts of phosphorous into rivers and oceans can give rise to algae blooms and subsequent anoxic conditions. Meanwhile, the farmland that produces our food becomes depleted in the element contained in the harvest. So the farmer adds fertilizer to replenish the phosphorous that is lost.

Like oil, most rich phosphate mineral deposits were once part of biological organisms. Petrified guano has accumulated on remote ocean islands where sea birds have deposited phosphorus for millennia. Other less clear phosphate concentration mechanisms are probably responsible for other rich phosphate rock deposits. There are not too many rich sources of phosphate rock on the planet. The biggest deposits are in Morocco and China. The U.S. also has significant deposits and produces most of what we need from deposits in Florida and a few other locations. Estimates vary on how much phosphate rock is economically extractable. Depending on who you believe, we’ve got enough to last for either 30 or 300 years. In 2008 the price of phosphate rock went through the roof with a 700% price rise in a matter of a few months. Prices dropped again as soon as the global recession took hold, but the sudden run-up illustrates the inelastic demand for this vital commodity, and forewarns what could come.

The ultimate solution is very low-tech. Efficient recycling of human waste could generate all the phosphorous that we need for agriculture and would end the phosphate waste stream that pollutes our waterways.

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