In my extensive research I could see that food production total really peaked around 2000. A very rounded peak, but decreasing faster and faster as the effects of water scarcity, a myriad forms of soil loss, more expensive fuel and transport, fisheries collapse, pollution effects, and AGW.
People talk about increasing food supply by less waste, drip irrigation, exotic seeds, going vegetarian, and even eating algae and organic plastic, ad nauseum. It is bad enough they stretch it now with chemical additives labeled sometimes, "natural". American food habits are very bad, from Monsanto to the obese consumer. Sure, people eat too much meat often, and on average, don't bother reading labels.
So with the 35 to 50% loss of food from 1993 level calories per person per day, the crash will occur in the early 2040s. The tipping point of runaway malevolent climate change will have passed, so the forced emissions reduction by 90% death rate then will do no good. The survivors will not make it very long.