Watch that Threshold

As a Managing Director in a farmland investment fund I want to make sure that our assets are going to maintain their value long into the future.  Farmland LP is unique in that we consider climate change when evaluating the  land we purchase and how we steward it.

In this post I’ll explain why this is important and why sustainable agriculture adds value in this context.

Key Food Crops Vulnerable to Climate Change

Most of the headlines regarding climate change and agriculture highlight impacts in the tropics, especially Africa.  Consider this recent article from Business Daily, an African news source:

A forecasting scenario done by the Institute of Security Studies, a pan-African security analysis think-tank showed that by 2025 the continent will suffer from hunger and resource conflicts because of climate change.

On agriculture, the forecast notes; “harvests could shrink, possibly severely in the Sahel, West Africa and Southern Africa. Agricultural yields from some rain-fed crops could be reduced up to 50 per cent by 2020 in some countries, most seriously affecting small-scale farmers and subsistence farmers as a result of desertification, soil salinisation and water scarcity.

Less appreciated is that some major crops in the U.S. could be facing similar declines, though not likely by 2020 as in Africa.  In a fascinating and disturbing study published this year in the Proceedings of the National Academy of Sciences, a group of U.S. researchers used historic yield data to understand how corn, soy and cotton respond to environmental factors.  The goal was to create a crop model based on actual farm yields across a wide geography using “natural experiments” such as typical and atypical weather events across the nation.  What they found was that temperature alone was a rich explanatory variable (their models correct for changes in precipitation, technology, and variation among site soil factors).

I have copied a graphic from their paper showing  “the response curve” of yields to temperature for corn, soy and cotton.  The key point is that yields drop dramatically at a threshold that is just above current temperatures.


Image caption: Figure from Schlenker et al., 2009 with explanatory text and graphics added.

They then modeled future climate under a couple of scenarios and derived yield losses accordingly.  The take home message of the results is given in last sentence of the abstract:

Holding current growing regions fixed, area-weighted average yields are predicted to decrease by 30–46% before the end of the century under the slowest (B1) warming scenario and decrease by 63–82% under the most rapid warming scenario (A1FI) under the Hadley III model.

Geography and Methods Matter

I am certainly concerned about the impact of climate change on food production, but I also see opportunities for where to allocate a farmland investment portfolio and how to adapt to changes on the farm.

Climate models and their outputs are in the public domain and if studied reveal that geography matters.  Some places are projected to be disrupted far less than others even under a wide-range of scenarios, making adaptation much easier and yields comparatively much higher.  Since farmland values and cash flow are tied to production levels minus costs, we can make some educated decisions on where a long-term investor might want to be to reduce the risk of loss.

Management practices also make a huge difference in productivity.  When looking at aggregated data, yields are averages among many different farms and farmers.  The crucial questions to ask are:  What is the range?  How can best practices be more widely applied?  Again, best practices are not mysteries, they are innovations that have not been completely adopted.

Climate change portends not just higher average temperatures, but a more volatile environment with greater extremes.  Several recent reviews of potential methods to feed the world with reduced environmental impact and less inputs all conclude that organic, especially agroecological, farming is the way to go.  According to the Food and Agriculture Organization of the United Nations:

Organic farms grow a variety of crops and livestock in order to optimize competition for nutrients and space between species: this results in less chance of low production or yield failure in all of these simultaneously. This can have an important impact on local food security and resilience. In rain-fed systems, organic agriculture has demonstrated to outperform conventional agricultural systems under environmental stress conditions.

If we are going to avoid stumbling off the threshold, the science of ecology, with its emphasis on diversity and resilience, will be integrated with agronomy to adapt to changes in the environment, resource availability and economics.