food & agriculture
Crop diversity and human nutrition
Global crop yields have risen dramatically since the mid-20th century. Yet crop yield&mdashthe most common metric of agricultural efficiency&mdashis not necessarily a good proxy for the more-than-50 nutrients needed for a balanced human diet. Colleagues and I have shown that crop nutrient production was stagnant or declining while yields were growing from the mid-20th century1. If the challenge of the 20th century was to feed the world, the challenge of the 21st century is to feed the world well, while minimizing environmental impact. I have shown with colleagues that nutrient diversity in national food supplies can be as important to nutrition-related health outcomes as aggregate caloric availability2. There is, thus, growing consensus that optimizing food systems for micro- and macro-nutrients could more effectively address hunger and undernutrition than strictly increasing total food production.
Optimizing food systems for nutrients is a multi-dimensional optimization challenge&mdashit is relatively easier to make policy around a single target (i.e. yield) rather than multiple targets simultaneously (i.e. protein, energy, folate, vitamin A, etc.). My interest in nutrition systems began by applying ecological functional trait diversity metrics&mdashdesigned to measure the diversity of functional properties in natural ecosystems&mdashto quantifying the nutritional diversity of food systems2, 3. I have argued that functional trait approaches could transform our understanding of agricultural systems4, but one of the limitations of this approach is that some trait metrics are mathematically complex and challenging to understand for some applied users. I have also been working to develop easily intuited nutritional diversity metrics1, 5. We have begun to apply these metrics to understand differences among alternative production systems and recommend how to optimize food systems for nutrient diversity2, 5, 6.
Impacts of and adaptation to climate change
Many estimates of climate change impact on agriculture focus on modeling crop physiological responses. Those potential yield losses can be mitigated by farmer actions to adapt to changing climate. Altering agricultural practices, such as switching crops or using irrigation, can reduce the impact of climate change. Thus, estimates based only on crop physiology likely over-estimate the economic damages of climate change to agriculture. Drawing on economic theory developed by David Ricardo, I use an econometric modeling approach that allows for farmer adaptation to climate to estimate the net revenue consequences of climate change in southeastern Senegal7. This approach generates more accurate estimates of economic impacts, but does not account for the specific adaptation strategies used by farmers. I have worked with global-scale household survey data on farmer decision making to better understand if there are general patterns in how and why farmers adapt in response to potential climate change8. My current work in this area focuses on farmer choice around endemic "traditional" crops in Senegal and Guinea.