You seem outraged in some way by what Battisti and Naylor presented. I think that they did a pretty good job though I would like to see an update taking into account the last 4 years of data to see if their charts changed much. It is not like they are wild optimists or anything like that as their projections indicate eventual catastrophe.
Hmm, I'm not sure what I said that sounded outraged - not at all - I think it's a useful contribution, just I'd have liked to see a bit more nuance and detail especially in the lead in to 2050. That - and I'm not sure how convincing the benchmark of "hotter than ever before" is in the sense that that allows for plenty of temperatures that aren't quite as hot as all time records but are still damaging to output.
Nonetheless, those are damning long term projections for agricultural output and the lag with which the climatic system responds means that immediate action would be required to affect them.
One of the things about global food production which needs to be kept in mind is that our recent years food shortages in various countries which precipitated problems (Tunisia, Egypt, etc.) are NOT due to a shortage of food production. The crises were caused by two main factors. 1. Affordability. In other words there was plenty of grain but some could not afford to buy it. 2. Food to fuel programs. The price of the grain was artificially high due to grain to fuel conversion programs designed to pad the pockets of the agriculture industry. In other words welfare politics is disrupting the market.
I agree entirely - there is plenty of slack if biofuels are cut out, wastage reduced, the effects of affluence on diet mitigated (ie people don't consume so much meat) and purchasing power better distributed so all people could at least afford food.
My problem is - I'm not convinced those things are going to be resolved, however logical and rational it would be to do so.
One of the dire implications of the 2050 chart is that major drops in yields in the tropics (they ARE in critical territory by then) will have set in by 2050 so there is going to be some starvation in Africa and other locations before then. At first due to affordability and then due to shortages. For them collapse will come sooner than to us. But it always was going to work out that way. So maybe by your way of counting this means that collapse comes a little sooner than 2050? I admittedly count differently.
I think we broadly agree on the implications of collapse. Certainly, when I use the term I am talking about more than economic or financial collapse as occurred in Russia and Argentina during respective debt defaults (as was accompanied by some decay in social cohesion, but was ultimately recoverable).
My definition requires widespread conflict, general disintegration of social cohesion, followed or accompanied by widespread famine and a high mortality rate (and a greatly reduced and technologically limited final population level). Clearly for global collapse that must have reached virtually everywhere (as opposed to just a few societies as is pretty much normal historically).
I don't think we really disagree about the input factors? I may be ascribing different weights to some of them - or I might be tossing in a larger precautionary fudge factor for "unknown unknowns". I also don't think it's only about agriculture - but also about the behaviour of large angry populations.
Perhaps I could cite Syria as an example illustrating my thinking? They experienced adverse agricultural conditions via drought (quite likely influenced a bit by climate change) and a food price shock. They proceeded into what I think it's fair to call a civil war, which has now greatly further reduced their agricultural output. If you look at climatic factors and agriculture alone - I don't think you would predict their current agricultural output accurately? Clearly, right now they should still be able to grow a significant amount of food - just - they're too busy fighting...
I ascribe quite a high weight to the synergistic interplay of related factors in their ability to rapidly worsen and accelerate the situation - you may think the overall system is more resilient in this respect.
Another example of my thinking - how secure long term do you think Morocco is? They supply, unless I'm mistaken, the majority of the agricultural phosphates used by Europe. That's another factor I weigh fairly heavily - reliance upon less stable regions for key resources (which get a lot more expensive if you need to fight wars for them). I grant that right now, Morocco doesn't seem immediately precarious (and is just a convenient example of a critical resource dependency with implications far beyond the local region) - but if you're looking ahead further?
I digress from the direct impacts of weather upon agriculture though, I appreciate.