Mass starvation event became a lot more likely.

??? Firstly, my post was a funny one about piss.

Secondly, "It is estimated that a third of annual global food production uses ammonia from the Haber–Bosch process", so, averaging 30%, not 70.

Thirdly, fossil-fuel based fertilizer production is unnecessary and has harmful side-effects. It's doable completely without fossil fuels, and the fact we've not divested even more out of that already is our own stupidity, not a reason to say "fossil fuels good".

..excessive use of nitrogen-based fertilizers has severe environmental consequences, including biodiversity loss, soil and freshwater degradation, and substantial greenhouse gas emissions.

85 to 95 per cent of nitrogen applied to soil is lost and does not make it to us as food.

Food security is possible with less nitrogen: with massive overuse and low use efficiency, much nitrogen can be spared without reducing yields. With nitrogen scarcity and soil mining, recycling should be increased before and besides adding new external nitrogen.

Fourthly, given the amount of BEANS I eat, and they in fact do their own nitrogen fixing. I daresay my percentage of fossil-fuel derived fertilizer-enabling nitrogen is actually much lower.