Food Supply and Climate Change

My friend Wolfram Schlenker has written a paper with David Lobell and Justin Costa-Roberts that uses data from 1980 to the present to study how climate conditions affect agricultural production.   The technical version is posted here.

Their Abstract

“Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. Here, we show that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends for 1980–2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8% and 5.5%, respectively, compared to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, CO2, fertilization, and other factors.”

These researchers are acting as an “early warning system”.  By giving us a collective “heads up” about the challenges we are likely to face, they help us to adapt to climate change.   Rather than being complacent about the future of our food supply, their estimates should make for profit “agribusiness” and farmers aware of the future impacts on yields and this will nudge that self interested actors into thinking about how to “change their game”.  We can grow food in different places within a nation.  Nations can import food from other locations and export other products for which they have a comparative advantage at.   If we insist on continuing to use the same locations for growing food, then we will need to think about strategies that yield output that are less risky in the sense that yield is less sensitive to climate conditions.     Economists are in deep thought about how “real world” farmers will cope with changing climate conditions.   Here  is an example from Africa.  The authors collected detailed information on farming output and local climate conditions.  Note that any set of correlations estimated do not represent “laws of physics”.   If farmers become aware that they will face more extreme conditions then they can make investments to be prepared for them and such adaptation further lowers the yield costs of future climate shocks.   The key here is to “plan ahead” and to have the resources to be able to invest so that you can “change your game”.

Author: Matthew E. Kahn

Professor of Economics at UCLA.

4 thoughts on “Food Supply and Climate Change”

  1. We can grow food in different places within a nation.

    But of course! There is just oodles of productive land just sitting around, doing nothing. And Canada: Ohhhhh…Canada! With all that land to the north, just sitting there, waiting to be cropped! Never mind that it is low-fertility and there is no farming infrastructure there! We must adapt!

    But much more to the point, we have known for two decades that the yield curve per capita is declining. Throw in a couple curveballs and human population growth, and you’d think adept, flexible big biness would have been on the case years ago, to capture profit and corner the market. It has taken a very long time to twiddle at the margins and what is there to show for it?

  2. “If farmers become aware that they will face more extreme conditions then they *can* make investments”

    You see here the moving of the goalposts?
    We’ve switched from “the correct change will happen” to “the correct change could have happened”. The subtext, of course, is “those stupid farmers — they knew what to do, but persisted in listening to Exxon rather than Gore, and now they have no-one to blame but themselves”.

    This, of course, is without even mentioning such minor issues as national boundaries, or the fact that in the world we actually live in, as opposed to some imaginary world, I, Joe Farmer, don’t have any right, legal, customary or otherwise, to just abandon the current land I work to move onto someone else’s land.

    Or, to put it differently, LA is presumably going to become hotter and thus less desirable over the next thirty years. What is Matthew’s plan for dealing with this?
    (a) Enter into some complicated financial transaction that hedges the possible decline in value of his house?
    (b) Plan to move to Canada unhindered, and then just occupy one of the many houses going empty in Canada? OR
    (c) Ignore the issue as irrelevant given the many pressing problems of today? After all, he might be dead in thirty years, and then it will be someone else’s problem.

  3. Did someone reduce the price of quotation marks today? “early warning system”? “laws of physics”? Really?

  4. I, Joe Farmer, don’t have any right, legal, customary or otherwise, to just abandon the current land I work to move onto someone else’s land.

    This is an excellent point: farmers, suffering so many crop losses that they must migrate, and despite the numerous crop failures can sell their land profitably (presumably to developers building under the old model to slap up distant, auto-dependent McSuburbs) and thus are still rrrrrich, move north and purchase farmland and invest in infrastructure and soil amendments, commence farming, and commence making profit!! Wow! Reality is grrrrrrrreat!

    Or maybe property laws will…erm…adapt and we’ll be able to move onto someone else’s land – that’s wishing for adaptation ideas, bay-bee!

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