FSE visiting scholar on extreme weather, economics and interdisciplinary learning


Photo credit: 
Ross Feehan

The United States continues to endure the worst drought to hit the country in over 50 years. Although conditions have improved, 53 percent of the US is still experiencing moderate or worse levels of drought. The United States Department of Agriculture (USDA) projected last week that the drought will reduce the nation’s corn yield by 13 percent and soybean yield by 12 percent. As the world’s largest exporter of corn, soybean and wheat, this major disruption in U.S. supply is already having an impact on global food prices.

Is this summer a glimpse of what our future could look like under a changing climate, and what does that mean for the world’s poor who are disproportionately impacted by volatile food prices? What policy options are available to help avoid a repeat of the 2007-2008 food crisis? I sat down with FSE visiting scholar Thomas Hertel, an agricultural economist from Purdue University, to discuss these questions and related research as he wraps up his sabbatical year here at Stanford.


DEAN: The current drought has already had a dramatic impact on US corn prices, exceeding record highs of $8 a bushel. While American consumers are unlikely to feel the impacts until next year, the spike in corn prices has sparked debate over whether to drop or temporarily suspend US ethanol mandates to free up supply and ease the pressure on world food prices. In April, you published a paper in Nature Climate Change with Stanford environmental scientist Noah Diffenbaugh that looked at this very scenario.

How are current biofuel policies affecting the market’s ability to respond to extreme weather events like the current drought?

HERTEL: The remarkable thing about that paper is how timely it was. We predicted a volatile interplay between an extremely hot summer and the Renewable Fuel Standard for corn ethanol, and that is what we are now seeing, with the value of the mandates’ Renewable Identification Numbers (RINs) accruing greater value as the drought deepens. There are increasing calls for a waiver of the mandated 13.2 billion gallons of corn ethanol needed to meet this year’s federal renewable-fuel standards. This new source of demand (about 40 percent of production last year) has absorbed virtually all of the increased output the US has generated over the past eight years. By limiting the ability of commodity markets to adjust to yield fluctuations, biofuel mandates work in exactly the wrong direction. These price spikes are likely to be even larger in the future if these policies are not altered.


DEAN: In that same paper you warn that extreme weather events, like the current drought, are likely to become more common and potentially even more intense under a changing climate. To better understand the impacts of climate change on global agricultural production, trade, prices and poverty you have developed a global trade analysis model (GTAP), now used by over 10,000 members. Some of those results were published in a 2010 paper with FSE fellow David Lobell and FSE affiliated researcher Marshall Burke.

What have been some of the most interesting findings to come out of that model?

HERTEL: Prior to the publication of our 2010 paper in Global Environmental Change, most studies of climate change and poverty focused on the likely impact on prices and low income food consumers. Our paper was one of the first to examine the impact on wages and farm incomes. We found that low income farm households in regions of the world that are relatively less hard hit by climate change may actually benefit from the ensuing rise in world prices. Of course, low income consumers worldwide, as well as farmers in the regions hardest hit by climate change, such as Southern Africa and South Asia, will be hurt.


DEAN: Poor households in developing countries spend a disproportionately large amount of their disposable income on food. Even small price spikes can have a large impact.

What policies are needed to help protect the world’s poorest from price volatility?

HERTEL: This is an important question. Being a trade economist, I think immediately of trade policies and their role in improving or worsening the situation. From a global perspective, the best thing that can be done is for all regions of the world to share in the needed adjustments to events like the US drought of 2012. If all countries were to adjust their corn use by just a modest  amount, the shortfall could be accommodated more easily. However, the evidence from the 2007-2008 commodity crisis suggests that many countries – most notably India and China – responded to the crisis by adjusting border policies so as to shield domestic consumers from the price rise, thereby failing to share in the adjustment. This, in turn, made the world price rise larger and worsened the situation for low income households in other developing countries.


DEAN: In addition to focusing on climate change impacts on agriculture and poverty, you have a long-standing interest in agricultural impacts on the environment, and the role economics can play in mitigating agriculture’s destructive planetary impacts. The latter is particularly important given that agricultural production accounts for 70 percent of global freshwater consumption, 38 percent of total land use, and 14 percent of the world’s greenhouse gas emissions.

How are economic forces impacting the kind of farming we see today?

HERTEL: One of agriculture’s most important impacts on the environment has been its contribution to global greenhouse gas emissions (GHGs). Farming accounts for a disproportionate share of GHGs, including nitrous oxide emissions from fertilizer applications, methane emissions from livestock and paddy rice, as well as indirect emissions from the conversion of tropical forests to agricultural uses. There is little doubt that the globalization of agriculture has contributed to an acceleration of land conversion in some regions which had previously been insulated from world markets. New agricultural technologies offer great hope for moderating such GHG emissions – both by reducing the emissions intensity of agricultural production and by reducing the total amount of land required to feed the world. And there is evidence that more rigorous enforcement of restrictions on land conversion in places like the Amazon can have a tangible impact on global emissions. So the answer lies in a combination of investments, regulations and enforcement. We have explored the potential for agriculture and land-based mitigation policies to contribute to reduced GHG emissions – as well as the implications for food security – in a joint project with the UN-Food and Agriculture Organization. These findings are forthcoming in a paper in the Proceedings of the National Academy of Sciences.


DEAN: While at Stanford, you have had the opportunity to work closely with climate and earth system scientists to conduct research on the energy-water-land-agriculture-climate nexus under the umbrella of John Weyant’s Integrated Assessment Modeling (IAM) project and with former Purdue colleague, Noah Diffenbaugh.

How did you enjoy working in such an interdisciplinary environment?

HERTEL: This was the first deeply interdisciplinary experience of my career and it was both challenging and rewarding. Noah is the person who first stimulated my research interest in climate change five years ago. The idea that extreme events could have an important impact on agriculture, food prices and poverty is something that we have been exploring intensively since that time. However, it was only in the context of this sabbatical—with the help of Martin Scherer and Monika Verma—that we were able to really get our teeth into the issue, resulting in the April paper.


DEAN: You also taught an interdisciplinary graduate seminar with FSE fellow David Lobell on global agricultural land use change in 2050.

What sort of lessons did you learn from teaching an interdisciplinary seminar?

HERTEL: I really enjoyed the opportunity and the challenge of teaching an interdisciplinary course. I was fortunate to work closely with David Lobell in designing this course, as the structure was different from the typical economics course which I have taught in the past. Teaching the course also changed my perspective on which research questions are most important. Sometimes the points that most intrigue economists are of little broader relevance, while some of those issues which seem obvious to economists are deserving of much greater attention, more thorough investigation and better communication to the broader scientific community. I plan to offer this course when I return to Purdue, and I am also planning to write a textbook based on this course.


DEAN: You have also been working on the launch of an open source data program called GEOSHARE (Geospatial, Open-Source Hosting of Agriculture, Resources and Environmental Data).

What does GEOSHARE do and why is it needed?

Hertel: Feeding 9 billion people in 2050 in the face of a changing climate, while preserving the environment and eliminating extreme poverty, is one of the most important challenges facing us today. Yet the data currently available to understand how global and local phenomena affect the agriculture-environment-poverty nexus are insufficient to advance needed discovery and enable effective decision making. In order to address this limitation, we have initiated GEOSHARE. During my time at Stanford I was able to finalize funding for a two-year pilot effort aimed at providing proof of concept. It will prototype this freely available, global, spatially explicit database which will be accompanied by analysis tools and training programs for new scientists, decision makers, and development practitioners.


What will you take away with you from your time spent here on the Farm?

HERTEL: I greatly enjoyed my colleagues and conducting research, auditing courses (including a course in Geographical Information Science and David Lobell’s course in Climate and Agriculture) and teaching. But I also had great fun cycling and hiking in the hills around Palo Alto, windsurfing, singing in a local choir, and partaking of all that San Francisco has to offer. This is a lovely place to spend a sabbatical leave!