It's also worth noting that in the first world for "food-as-it's-consumed" the share of agriculture is just 10%-20% (depending on how it's consumed) of the final value, the majority of the cost comes from processing, transportation, retail, cooking and service or delivery; so if the price of agricultural products leaving the farmer would double, the increase in total price would not be as big. Of course, the poorer consumers in third world with actual problems with food security would bear the full effect of such a price increase.
It would impact poorer consumers, though not evenly. The population facing the most food insecurity issues, subsistence farmers, would be largely unaffected, since they generally aren't using artificial fertilizer.
