This week, while reporting a story on a new reaction that breaks nitrogen triple bonds, I talked to MIT chemist Christopher Cummins about fertilizer. It's something we take for granted, but ammonia fertilizer feeds the world, and making it requires large amounts of energy and fossil fuels. In order to save on energy, chemists are working on enzymes that mimic bacterial enzymes to "fix" nitrogen into bioaccessible ammonia at low temperatures.

But nitrogen isn't the only fertilizer we need to worry about, says Cummins. Modern agriculture is also reliant on phosphorus sourced from rocks and that is a non-renewable resource, like oil. According to a review published earlier this year in the journal Global Environmental Change, current global phosphorus reserves may be utterly depleted in 50-100 years, and production will peak in 2030. These resources are concentrated in Morocco, Chile, and the US, and, says Cummins, "many of the readily accessible mines have been used up."

"Phosphorus is the least abundant of all the biogenic compounds," he adds. "If you run out of one of those elements, you can't make life." With the global population expected to reach ten billion in 2050, this is likely to be a major problem unless these resources are managed better, starting soon.