It turns out that Pistachios, a billion dollar crop in California, could be threatened by warming winter within the next 20 years.While the scope and magnitude of our current climate crisis might be unprecedented in human history, this is not the first time that humans are facing climatic challenges in agriculture. Olmstead and Rhode show how, through the 19th and 20th centuries in North America, wheat growers managed “…to push wheat cultivation repeatedly into environments once thought too arid, too variable, and too harsh to farm”. The transition was made possible mostly by the development of new varieties. Plant breeding toward that end required information on the climate both in the progenitor native areas and the areas where the eventual new varieties would be planted . Adaptation to climate can be on the physical dimension as well. Specific interventions can be designed to change the physical environment surrounding plants. The most obvious intervention is building irrigation systems, to compensate for lack of adequate rainfall and soil moisture. But examples of adaptation to temperature by physical means exist as well. This type of intervention is common for a left tail effect: frost. To avoid it, only a slight increase in temperature is required, and growers know how to do that. Some examples for dealing with frost are hundreds of years old. The Tiwanaku civilization formed a system of raised fields on the shores of lake Titikaka in the 7–12 centuries C.E. Fields in select locations were raised with extra soil,plastic flower bucket up to a few feet above the ground level. Water from nearby springs was diverted and run through canals dug in these raised fields.
This provided not only moisture for the plants, but also converted the top soil level into a large heat storage unit. On frost nights, which are common in this high area, the heat stored in the soil kept the near-surface temperatures on raised fields higher than the normal air temperatures, preventing plants from freezing . Without modern weather instruments, the Tiwanaku realized that slight differences in ambient temperatures can have crucial consequences, and planned their fields according to their understanding of the climate. This system yielded far better than regular dry farming practiced before in this area, and supported a larger population than the one residing on the lake shores in the 1990’s. Eventually, as climate became drier, the water level of lake Titikaka dropped and the springs dried up, resulting in the collapse of the Tiwanaku culture . Despite its eventual failure, this technology was successful in abating frost damage for centuries, maintaining a population of hundreds of thousands and showing the power of human intervention on the field level to tackle a temperature distribution tail challenge. In Europe, traditional methods of dealing with frosts in vineyards include lighting small fires or “frost candles”. A more modern approach uses big fans, circulating the cold air in the inverted layer with the warmer air on top of it. Farmers have been using “air disturbance technology” in the US since the 1950’s . Wind generators are used around the world to protect wine grapes, fruits, and even tea from spring frosts. In some cases, a similar effect can be achieved with sprinklers . Interestingly, little economic literature has focused on air disturbance technologies. Stewart, Katz, and Murphy assess the value of weather information in the Yakima Valley of central Washington, in the context of frost prediction and air disturbance technologies. This descriptive study was published in the Bulletin of the American Meteorological Society. Searching the EconLit database for “frost” in article titles returns only four results involving actual frost in agriculture, none dealing with temperature altering.
A search in the abstracts of papers published by the American Journal of Agricultural Economics results in two papers, neither mentioning air disturbance technologies. The seeming dis-interest in these technologies is even more peculiar in 2019, when weather information is more accessible than ever: air disturbance systems are now sold with online communication to weather services, with the option for automatic operation in case of frost, and can often be switched on and off remotely. They are probably more efficient and valuable than ever before, given advances in technology and the high value of certain frost-sensitive crops. Technologies such as air disturbance are examples of a concept I call “Micro-Climate Engineering” . These are relatively small interventions in temperature distributions, limited in space and time, which aim to avoid the nonlinear effects of the extremes. The frost examples discussed above deal with left tail effects. There are also technologies available to deal with right tail effects, which is the focus of my last chapter. The final chapter of this dissertation deals with an MCE proposal for California pistachios. Chapter 3 deals with the threat of warm winters on pistachios, estimating the potential losses to this high value crop from climate change. Chapter 4 deals with a proposed solution. The MCE technology proposed for this challenge is spraying the dormant trees with kaolin clay, a non-toxic white substance which reflects the sunlight. Sprayed trees have been shown to experience lower temperatures than control trees, and their yields were higher. This intervention requires precise hourly measures of temperature, so growers can track the buildup of special temperature metrics and decide if and how much treatment is required. Using the pistachio yield-temperature response, estimated in the previous chapter, I build a model that integrates MCE in the pistachio market. The model can be solved with and without the option to use MCE, under various weather realizations. The value of MCE for California pistachios is calculated as the difference in welfare measures attained in each case.
The expected net present value of MCE in pistachios for 2020-2040 is assessed in billions of US dollars. This is yet another example of the potential use of weather information for dealing with climate change challenges in agriculture. Micro-Climate Engineering might remind some readers of Geo-Engineering, a controversial climate change adaptation concept. Geo-engineering proposals involve global scale interventions in the atmosphere and hydrosphere that would revert some of the changes in the total temperature distribution worldwide . In contrast, MCE is a small scale concept, aiming to tweak the temperature tail distributions where necessary rather than shifting the entire distribution year round. Many MCE technologies already exist and are used by growers, making sense both on the technical and economic dimensions. I believe many more examples are out there to be found, and many more will evolve as growers adapt to climate change.This chapter assesses the gains from a weather service provided by the California Department of Water Resources : the California Irrigation Management Information System . Established in 1982, it now comprises of hundreds of weather stations, scattered in many of the growing regions in California, and centralized computing systems for distributing the information and interpolating data between the stations. The intended purpose of CIMIS was to provide accurate real-time information for growers to optimize irrigation and save water. Specifically, many CIMIS stations include evapo-transpiration sensors, applied on specially maintained turf. Agronomists have been publishing crop coefficients, which serve to transform the turf-based ET measures for use in various commercial crops. This way,flower buckets wholesale growers can estimate how much water has been used by their plants, and plan replenishment of soil moisture accordingly. CIMIS also reports other weather variables, such as temperature, relative humidity, wind speed and direction, and soil temperature at the station. It does not offer forecast services. CIMIS has become a staple of agricultural practice and research in California. Searching for it on Google Scholar results in 2,860 entries for articles and publications. The gains from CIMIS have previously been analyzed by a team of researchers from the University of California – Berkeley , and the findings were published widely . This report used a survey methodology, and found a 13% applied water reduction with CIMIS, 8% yield increase, and a total economic gain of $32.4 million yearly. The 1996 report also found some examples of unintended use of CIMIS, which in fact delivered a substantial portion of the gains. For example, while the system was mainly designed for improving irrigation performance and water saving, the researching team found that there are many gains from CIMIS use in pest management. CIMIS detailed temperature data are used to calculate pesticide application timing, reducing the amounts of pesticide and increasing yields. This chapter presents and analyzes the main findings from a more recent report, prepared for DWR by David Zilberman, Itai Trilnick, and Ben Gordon. This report was meant to update the knowledge on the current uses and users of CIMIS, its economic gains, and potential future improvements. The full report is yet in the writing process. However, several patterns and conclusions can already be drawn, and are presented in this chapter.
The study is based on a survey of CIMIS users. Before running the survey, extensive interviews were held with various users to gather narratives about the roles of CIMIS in different contexts. These interviews provided a first qualitative picture of current CIMIS uses and interactions with other technologies and practices. They suggest that CIMIS has indeed become a mainstay in California agriculture, especially for growers relying on drip irrigation. However, many farmers access CIMIS indirectly through consultants, and might not be aware of the uses and benefits of the system. With the advance of alternative decision making tools , CIMIS is now part of a larger information eco-system. The interviews showed that the public availability of CIMIS data, including historic records, are highly regarded among users. This historical and cross-sectional information store is extremely valuable for decision-making and research. It is essential for calibrating other weather tools, verifying their results, and designing water management schemes that require knowledge of the historical distribution of weather variables. In addition, it may even be used to more accurately value farmland. Interviews were followed by a small survey, carried out by phone and aimed at assessing the initial insights from the interview. The final step was a full scale online survey, sent to all registered CIMIS users. Results from this survey are the basis for economic value calculations. CIMIS, an invitation to participate was also sent by email to mailing lists provided by the CIMIS team. The survey included some general questions, directed to all audiences, and questions tailored to specific user groups identified in the initial survey: growers, consultants, users in landscape management, regulators, researchers, and others. The CIMIS team decided that the survey will not include direct questions about water use, costs, and willingness to pay for CIMIS services, especially when addressing growers. These questions were deemed too intrusive, jeopardizing both the response rate and general trust of users in the CIMIS system. This meant that a direct WTP approach, like the ones used in the previous study of CIMIS and the one used by Anaman and Lellyett , would not be possible. Most questions were framed either in Likert-like scales or as a relative response . The analysis of the results uses indirect assessing of CIMIS impacts, using these types of responses and outside information. The online survey was done on a commercial platform, Survey Gizmo. It is worth noting that most registered users are not active. In fact, CIMIS user statistics show that a relative small percent of registered users had logged in and extracted data from the system in the year before the survey. Altogether, we have 3,057 responses, out of which 2,358 are complete.The breakdown of self-reported user types is listed in Table 2.1. About 1/4 of our respondents report their primary activity, as it relates to CIMIS, to be agriculture. The second largest category is “other”, encompassing a mix of respondents who, in our opinion, should have picked another definition, and a few others who seem to use the data for personal research. This category has gardeners, nursery workers, water consultants, government workers, and a few retired people working on individual projects. We did not reclassify obvious mis-responses, as that would not change the fact that they ended up answering a different set of questions than their “real” category. The third category is government workers, followed closely by research, environmental consulting and landscape management.