29 August 2012

The sky is falling!

Amongst dire warning of pending global vegetarianism, the Guardian notes
"The UN predicts that we must increase food production by 70% by mid-century"
What on earth does that mean? Is that a big number or a little number? A little context maybe? Handily I've just finished reading Tyler Cowen's excellent "An Economist Gets Lunch," in which he notes:
"during the period 1949-1990, new technological innovations boosted agricultural productivity by an average of 2.02 percent a year. From 1990 to 2002, this same rate of improvement fell to 0.97 percent"
Where would those rates get us? By my calculation, we would need a roughly 1.35% annual rate to get to that 70% increase target by mid century. A significant increase on the present rate, but certainly achievable in the context of past gains.

(Note also that this is just pure productivity gains from technological innovation - meaning no additional land inputs required)


TBot said...

Nice. But there are two countervailing issues: prices and production. Let's say food is scarcer, prices rise, and people will substitute away, so consumption baskets change. Since getting calories out of things like grain is more efficient (more output per unit land and sunlight) than out of things like meat, this would endogenously move more vegetarian diet equilibrium and wouldn't imply as high a rate of technological change to keep calories-per capita constant. Secondly, it's reasonable to say that output per unit land *won't* be stable over time: climate change + depletion (think fisheries) = lower levels of inputs. Combined with some (albeit slowing) population growth, this would imply higher growth rate (compared to a constant input level scenario) to keep calories-per capita constant. Not sure what the model wonks have decided will dominate and over what horizon, and models have to simplify, but I think growth rates implied by a constant-input and constant-consumption basket assumption may be a step too simple...

rovingbandit said...

No doubt it's too simple, but I think still useful mainly to just show the magnitude of a 70% increase over 40 years. Too many numbers thrown around in the media that our monkey brains are ill-equipped for intuitively understanding. It's the same problem as public finance with constant millions and billions being tossed around. Can you comprehend what a billion of something even looks like?

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