Vaclvac Smil (the second link above) makes some interesting points:
the International Fertilizer Industry Association, whose members include many of the world’s most prominent fertilizer producers, traders, and shippers… “does not believe that peak phosphorus is a pressing issue, or that phosphate rock depletion is imminent. Nevertheless, it believes that efforts to minimize phosphorus losses to the environment and optimize phosphorus use should be encouraged.”
And that is precisely as it should be, because wasteful use of all kinds of fertilizers is common and optimizing the applications brings substantial monetary and environmental rewards (phosphates are a major cause of aquatic eutrophication, their worst effects are persistent dead zones in many coastal areas around the world). Larger gains in reducing phosphate applications could be made by moderating typical per capita meat consumption, and a great amount of the element can be recovered from waste. In all Western countries, most fertilizers are now applied to feed not food crops, and hence moderating the current high rates of meat consumption (commonly in excess of 100 kg per capita) would reduce the amount of needed fertilizer. Such cuts would also have environmental and health benefits.
An even more important option – especially given the facts that much of modern meat, milk, and egg production is done in a concentrated manner, and that half of the world’s population lives in cities – is now available thanks to advances in phosphorus reuse from manures and municipal wastes.
h/t Roger Pielke Jr., via a tweet
Similarly, it is not the burning of fossil fuels, but their emission into the environment, that causes the greenhouse problem. This is the insight behind carbon sequestration.