By Bill Smith
Undoubtedly, the summer of 2012 will be remembered in the United States for record-breaking high temperatures and extreme drought. In July, over one-half of the U.S. was experiencing moderate to extreme drought (see National Climate Data Center – Drought), and for many regions the dry spell continued well into August. The most visible and immediate consequence of these extreme climate conditions was forest fires – the ~2 million acres burned by wildfires in July was the 4th largest on record (see National Climate Data Center – Wildfires). Yet, potentially even more critical, U.S. agricultural production was also impacted.
As of July 10th, 78% of U.S. corn – the leading agricultural export in the U.S. – was experiencing some degree of drought, prompting the World Agricultural Outlook Board to announce a 12% cut in 2012 U.S. corn production targets (see USDA). The U.S. accounts for nearly half of global corn production (FAOSTAT), thus, any decrease in U.S. output can have adverse effects on global corn prices. In turn, since corn grain is integral to food production (think meat, milk, and eggs), staple foods around the world will also experience significant increases in price. For the average American household, increases in food price will have nearly double the impact of changes in gas prices (i.e., food and gas account for 13% and 8% of the average American budget, respectively). For the tens of millions of people throughout the world near the poverty threshold (people who already spend the majority of their household budget on food), increased food prices could mean the difference between a diet that meets minimum nutrient requirements and chronic malnutrition (see Mother Jones). Ultimately, human well-being critically depends on affordable food.
A focus of my recent research has been U.S. biofuel production and policy, which also directly impacts U.S. corn production and export, and thus has the potential to influence global food prices (Smith et al. 2012). Currently, the most viable form of biofuel produced in the U.S. requires the edible part of corn as a feedstock (i.e., corn ethanol). In fact, roughly 40% of U.S. corn production – or nearly 20% of total U.S. agricultural production – was used for ethanol production in 2010 (RFS 2012). Next generation ethanol that uses the inedible part of plants (i.e., cellulosic ethanol) is currently under development. However, large-scale production of such ethanol remains indefinitely delayed due to challenges associated with breaking down the more complex cellulosic plant matter (Smartplanet). Despite the current unavailability of cellulosic ethanol, U.S. biofuel mandates – defined in the Energy Independence and Security Act of 2007 (EISA) – specify a domestic ethanol production target of roughly 136 billion liters by 2022, nearly a three-fold increase over current ethanol production (Figure 2).
The main objectives of my research were to 1) use high resolution satellite data on vegetation productivity to define an upper-envelope capacity for bioenergy production in the U.S. and 2) Compare my results with current biofuel production mandates to determine the overall feasibility of U.S. biofuel policy (Smith et al. 2012).
The key findings of my work suggest that U.S. biofuel mandates are not realistic, unless cellulosic ethanol production becomes available at the large scale. For instance, my results show that if we continue to meet annual mandates using solely current U.S. agricultural land, roughly 80% of agricultural productivity will need to be allocated to biofuel by 2022 (Figure 2, Figure 3). To put this into perspective, this would require more than a four-fold increase in corn production for biofuel, leaving only 20% of total agricultural production for food.
Instead, if we solely consider expanding agricultural land into natural areas, my results suggest nearly 60% of natural rangeland productivity would be required to meet 2022 biofuel mandates, nearly doubling total agricultural area in the U.S. (Figure 3). While this scenario avoids competition with current food production regions, the expansion of crop monocultures could have significant effects of biological diversity and species extinction rates. Furthermore, the utilization of natural areas would require infrastructure establishment resulting in large-scale fossil fuel energy inputs, which would essentially undermine the potential for biofuels to offset fossil fuel consumption.
Conversely, if cellulosic ethanol technology becomes viable, current harvest residuals including both agricultural (e.g., stalks, stems, etc.) and forestry (e.g. braches, slash piles, etc.) could be used to satisfy nearly 80% of the 2022 biofuel mandates (Figure 3). Unfortunately, cellulosic ethanol has failed to meet production mandates since 2009 (Figure 2). Ultimately, if corn ethanol production continues to compensate for missed cellulosic ethanol targets (Figure 2), the U.S. agricultural landscape will be significantly altered, which could contribute to a sustained increase in global food prices (Smith et al. 2012).
Satellite data improves our ability to estimate biofuel potential by providing a continuous measure of vegetation productivity for every square kilometer of the roughly 7.2 million square kilometers of vegetated land in the U.S. However, the results of our analysis are based on current trends in productivity, which leaves room for the question: could vegetation productivity increase in the future? Achieving yields that exceed natural rates of productivity would require either enhanced photosynthetic capabilities or reduced vegetation growth constraints; neither scenario is likely for the future. Despite a long history, genetic manipulation has yet to significantly increase the efficiency by which the photosynthetic machinery processes light energy. Thus, reducing vegetation growth constraints (e.g., extending the growing season, maintaining water availability, etc.) remains the best option for increased vegetation productivity and crop yield.
Irrigation – a very common management stagey – improves yields by reducing the period of time plants are water-stressed. However, evidence suggests current irrigation rates in the U.S. may already be unsustainable in many regions. For example, the Colorado River, a major irrigation source for western agriculture, currently operates at a maximum sustainability limit, with little to no of the peak renewable flow reaching the delta annually. Further, the Ogallala Aquifer, one of the largest ground water resources in the U.S., continues to be exploited (largely for irrigation) beyond its natural recharge rate, resulting in a significant depletion of an essentially non-renewable resource. Since roughly 13% of U.S. agricultural lands currently depend on irrigation, an equally likely scenario for the future may be decreased agricultural productivity as freshwater limits are exceeded.
Alternatively, climate change could present a viable mechanism for reduced vegetation growth constraints in the U.S. In theory, increased average temperatures associated with climate change should result in a longer growing season for U.S. crops, which, in turn, could result in increased crop productivity. Yet, climate change is also likely to impact rates of precipitation. In fact, recent research found 70% of U.S. counties are likely to experience reductions in freshwater availability due to climate change-driven increases in drought frequency (Roy et al. 2012). Thus, extreme climate events, like the drought experienced throughout the U.S. this summer, may become a more common occurrence as a result of climate change (Wired). Ultimately, if current climate projections are realized, the battle between food and biofuel will intensify, most likely at the expense of global food prices (Smith et al. 2012).