The Center on Food Security and the Environment is a joint effort of the Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment.
A team led by FSE fellow David Lobell has found a valuable, untapped resource in historical data from crop yield trials conducted across sub-Saharan Africa. Combined with weather records, they show that yield losses would occur across 65 percent of maize-growing areas from a temperature rise of a single degree Celsius, even with sufficient water.
Development of new crop varieties that are more heat and drought tolerant will be critical for successful adaptation to a warmer world. A recent 3 day meeting of international climate and crop experts at Stanford University focused on specific needs and promising approaches for improving crops. A meeting synopsis and recommended priorities can be found in a summary report, Climate Extremes and Crop Adaptation.
This study investigates the skill of linear methods for downscaling provincial-scale precipitation over Indonesia from fields that describe the large-scale circulation and hydrological cycle. The study is motivated by the strong link between large-scale variations in the monsoon and the El Nino - Southern Oscillation (ENSO) phenomenon and regional precipitation, and the subsequent impact of regional precipitation on rice production in Indonesia. Three different downscaling methods are tested across five different combinations of large-scale predictor fields, and two different estimates of regional precipitation for Indonesia.
Downscaling techniques are most skillful over the southern islands (Java and Bali) during the monsoon onset or transition season (Sep.-Dec.). The methods are moderately skillful in the southern islands during the dry season (May-Aug.), and exhibit poor skill during the wet season (Jan.-Apr.). In northern Sumatra downscaling methods are most skillful during Jan.-Apr. with little skill at other times of the year. There is little difference between the three different linear methods used to downscale precipitation over Indonesia. Additional analysis indicates that downscaling methods that are trained on the annual cycle of precipitation produce less-biased estimates of the annual cycle of regional precipitation than raw model output, and also show some skill at reconstructing interannual variations in regional precipitation. Most of the downscaling methods' skill is attributed to year-to-year ENSO variations and to the long-term trend in precipitation and large-scale fields.
While the goal of the present study is to investigate the skill of downscaling methods specifically for Indonesia, results are expected to be more generally applicable. In particular, the downscaling models derived from observations have been effectively used to debias the annual cycle of regional precipitation from global climate models. It is expected that the methods will be generally applicable in other regions where regional precipitation is strongly affected by the large-scale circulation.
In June 2009, a group of experts in climate science, crop modeling, and crop development gathered at Stanford University to discuss the major needs for successful crop adaptation to climate change. To focus discussion over the three day period, the meeting centered on just three major crops – rice, wheat, and maize – given that these provide the bulk of calories to most populations. The meeting also focused on two aspects of climate– extreme high temperatures and extreme low moisture conditions (i.e. drought) – that present substantial challenges to crops in current climate and are likely to become more prevalent through time. Other aspects of climate change such as more frequent flooding or saltwater intrusion associated with rising sea levels were not addressed, although they may also be important.
The current document is split into two sections:
The main target audiences for the document are donor institutions seeking to invest in climate adaptation, and climate and crop scientists seeking to set research agendas. We intend the term donor institutions to include private foundations, governments, and inter‐governmental organizations such as the World Bank and United Nations. An underlying assumption of the Stanford meeting was that there is a real and growing need to identify specific investment opportunities that will improve food security in the face of climate change. This is reflected, for instance, by the recent G8 announcement of a $20B investment in food security, the expectation of additional resources for adaptation from the Copenhagen Conference in 2009, and the emphasis of the Obama administration on food and climate issues.
This paper is part 2 of a two-part study evaluating the climatic effect of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region.
Part 1, using a set of sensitivity experiments, estimated the potential impact of observed landscape evolution, since the dawn of the Landsat satellite era on the near surface climate, with a primary focus on the alteration of the surface radiation and energy budgets and through use of high-resolution, 2km grid spacing, Regional Atmospheric Modeling System (RAMS) simulations with circa 1973, circa 1992, and circa 2001 landscape data sets.
In this paper, part 2, we address the role of the previously discussed surface budget changes and subsequent repartitioning of energy on the mesoscale dynamics and thermodynamics of the region, the effect on convective rainfall, and their association with the large-scale North American Monsoon System (NAMS). Our results show that contrasts in surface heating resulting from landscape change are responsible for the development of preferentially located mesoscale circulations, on most days, which were stronger for the 2001 compared to the 1973 landscape, due to increased planetary boundary layer (PBL) heating via enhanced turbulent heat flux.
The effect of these stronger circulations was to warm and dry the lower part of the PBL and moisten the upper part of the PBL for the 2001 relative to the 1973 landscape. The precise physical pathway(s) whereby precipitation enhancement is initiated with evolving landscape, since the early 1970s, reveals a complicated interplay among scales (from the turbulent to the synoptic scale) that warrants future research. Precipitation recycling, however, was found to be an important driver in the overall sustenance of rainfall enhancement.
Although this study was not designed to investigate other radiative forcing factors such as greenhouse gas emissions and aerosols, the results of our sensitivity experiments do suggest that regional land use change is an important element of climate change in semiarid environments characterized by large urban areas with scarce water resources.
This paper is part 1 of a two-part study that evaluates the climatic effects of recent landscape change for one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region. The region's landscape evolution over an approximate 30-year period since the early 1970s is documented on the basis of analyses of Landsat images and land use/land cover (LULC) data sets derived from aerial photography (1973) and Landsat (1992 and 2001). High-resoultion, Regional Atmospheric Modeling System (RAMS), simulations (2-km grid spacing) are used in conjunction with consistently defined land cover data sets and associated biophysical parameters for the circa 1973, circa 1992, and circa 2001 time periods to quantify the impacts of intensive land use changes on the July surface temperatures and the surface radiation and energy budgets for the Greater Phoenix region.
The main findings are as follows: since the early 1970s the region's landscape has been altered by a significant increase in urban/suburban land area, primarily at the expense of decreasing plots of irrigated agriculture and secondarily by the conversion of seminatural shrubland. Mean regional temperatures for the circa 2001 landscape were 0.12C warmer than the circe 1973 landscape, with maximum temperature differences, located over regions of greatest urbanization, in excess of 1C. The significant reduction in irrigated agriculture, for the circa 2001 relative to the circa 1973 landscape, resulted in dew point temperature decreases in excess of 1C. The effect of distinct land use conversion themes (e.g., conversion from irrigated agriculture to urban land) was also examined to evaluate how the most important conversion themes have each contributed to the region's change climate.
The two urbanization themes studied (from an initial landscape of irrigated agriculture and seminatural shrubland) have the greatest positive effect on near-surface temperature, increasing maximum daily temperatures by 1C. Overall, sensible heat flux differences between the circa 2001 and circa 1973 landscapes result in a 1 Wm-2 increase in domain-wide sensible heating, and a similar order of magnitude decrease in latent heating, highlighting the importance of surface repartitioning in establishing near-surface temperature trends. In part 2 of this study, we address the role of the surface budget changes on the mesoscale dynamics/thermodynamics, in context of the large-scale environment.
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Holly Gibbs is a David H. Smith Conservation Research Fellow in the Center on Food Security and Environment. Her research focuses on quantifying the ripple effects of globalized economic drivers on tropical forest conservation and food security. Dr. Gibbs develops statistical and GIS models to quantify and predict shifting drivers, patterns and consequences of tropical deforestation and agricultural expansion. In particular, she is working to better integrate land use science and economics to quantify and map the indirect effects of U.S. biofuels and climate policies. Much of this research aims to reconcile forest conservation, climate change and food security through improved policy and economic incentives.
She earned her Ph.D. from the University of Wisconsin-Madison in the Center for Sustainability and the Global Environment (SAGE) where a DOE Global Change Environmental Fellowship supported her studies. Her dissertation research quantified shifting pathways of tropical land use and their implications for carbon emissions. Throughout her Ph.D. she worked closely with policy makers, business leaders and environmental groups in support of the UNFCCC initiative to Reduce Emissions from Deforestation and Degradation (REDD). Prior to moving to Madison, Dr. Gibbs worked as a Post-Masters Research Associate in Oak Ridge National Laboratory's Environmental Sciences Division where she led remote-sensing and GIS research for global carbon and water cycle projects. She received a B.S. of Distinction in Natural Resources and M.S. in Environmental Science from The Ohio State University.
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Wolfram Schlenker was a former Cargill Visiting Fellow at FSE. His research interests include the economics of climate change, water rights, and their impact on agricultural output, as well as models of exhaustible resources with endogenous discoveries.
Schlenker is currently Professor ineconomics at Columbia University. He holds a PhD in agricultural and resource economics from the University of California, Berkeley (2003) and a Master of engineering and management sciences from the University of Karlsruhe, Germany (2000), as well as a Master of environmental management from Duke University (1998).