Research seeks relief for hot and thirsty farmlands

February 6, 2019

Torrid temperatures and parched land are among the harsh consequences of climate change, and scientists and policymakers around the world are scrambling to find ways to curb the harm.

Although remedies are needed urgently, narrow and quick fixes won’t cure a global crisis that is so complex.

Solutions, if they are to be adaptable and sustainable throughout the world, must consider a variety of factors – human, environmental and economic health and more.

In California’s Central Valley, UC-led research teams are creating innovative ways for gathering the vast information that policymakers need to protect overheated farmlands and workers.

One of the most productive agricultural regions in the world, the Central Valley accounts for 16 percent of US crop production and it exports $11 billion worth of its commodities to foreign markets. It employs more than 450,000 farmworkers, two-thirds of whom are Latinx.

Even with state regulations for reducing occupational heat exposure, 2,630 California workers suffered heat-related illness in 2014 and 18 died from heat stroke on the job, according to California’s Division of Occupational Safety and Health.

The real numbers are likely much higher due to underreporting, and with scorching temperatures in recent years, they are projected to become worse, said Jennifer Vanos, PhD, principal investigator of a study that looks at the hidden health costs of extreme heat exposure to outdoor workers in the Central Valley. The project is funded with a seed grant from The UC Global Health Institute (UCGHI) Planetary Health Center of Expertise (PHCOE).

“Producing certain fruits and vegetables is a labor-intensive process, and extreme heat significantly affects the manual labor capacity of workers and degrades overall health,” said Vanos, a biometeorologist specializing in how atmospheric processes, such as weather and pollution, affect human health.

“California – and the world’s outdoor workforce as whole – face increasingly serious trade-offs between labor productivity and worker health in the face of climate change,” said Vanos, who moved last fall to Arizona State University (ASU) from UC San Diego, where she ran the Laboratory for Urban Climate Instrumentation at the Scripps Institution of Oceanography. At ASU, she is an assistant professor in the School of Sustainability and member of the campus’ Urban Climate Research Center. She continues to lead the PHCOE-funded study in the California Central Valley.

The aim of the project is to provide information to help policymakers understand and balance the tradeoffs between productive and lower cost yields versus the health of the workers who naturally slow down in the heat or are forced to do so because of safety regulations, said Vanos.

Researchers are collecting the vast and minute details, often right from the fields, in hopes of answering questions such as: At what specific temperature do workers whither or become ill from the heat? What parts of the day are they most productive? How many bushels of crops are picked or gathered under specific weather conditions? What are the best times for breaks or at what point do you pull them from the fields? What will it cost employers to implement preventive health measures, such as providing shade, hydration or protective clothing? Are current safety regulations appropriate and cost-effective? How can farmers keep their workforce healthy, stay in business and feed a hungry world at a reasonable cost?

Vanos and other researchers in the field seek to use a wide variety of tools – from low cost sensors worn by workers to measure skin temperature and sweat rates, to weather and heat prediction technology targeted at precise locations.

“Currently, US-based interventions to reduce heat-related mortality and death are largely based on urban risk factors, and often apply merely one value––air temperature––to estimate heat stress, which is rarely the reason for classic or exertional heat stroke,” she said.

Key to the success of this study is its collaborative and interdisciplinary nature. While Vanos is a biometeorologist focusing on human populations and health, her co-investigators are Federico Castillo, PhD, an environmental/agricultural economist at UC Berkley, and Michael Wehner, PhD, a scientist in the Computational Research Division and Lawrence Berkeley National Laboratory, Berkeley, an expert in climate modeling. Data from the PHCOE Central Valley study will complement an ongoing National Science Foundation funded project by Castillo and Wehner that also analyzes heat events in a socioeconomic context with an emphasis on agriculture.

It takes a strong team of researchers in different specialties to find solutions for complex climate change-related problems, said Vanos.

“They range from sociologists and psychologists and public health officials, statisticians and climatologists, to physiologists and anthropologist,” she said. “And I’m missing many more disciplines that can come together to solve some of these big challenges.”

“All the solid data that we and other scientists collect are critically important in order to prepare, mitigate and adapt,” she said.

And the research, although focused specifically on California agriculture, could be applicable to other industries and all over the world where people are exposed to extreme heat. “To do it right and completely, will take time, but the payback and benefits could be huge,” she said.

Learning from how people manage drought

Michael Johnson, a UC Santa Barbara PhD student in geography, digs deep into how farmers, governments and waters users adapt to water crises brought on by climate change-related drought.

The effects of California’s drought are felt internationally, too,” said Johnson. “Drought not only impacts the local population but everyone that relies on California products, such as food. These transboundary connections mean local drought conditions in some places can have consequences on regional and global food security, health and well-being.”

While many studies focus on hydrological impacts of climate change on agricultural production and environmental degradation, his socio-hydrologic research aims at how human behaviors, beliefs and politics affect ground water levels, crop production and economic welfare of farmers.

Johnson and his advisor Keith Clarke, professor of geography at UC Santa Barbara, lead another Central Valley study funded by a seed grant from the PHCOE. They are designing a model that looks at behaviors and responses to drought, various plans to combat water shortages, the risks of those strategies, how decisions are made, and whether they worked or not.

Droughts already are a crisis in many parts of the world, and with climate change, they will be a long-term problem looking for solutions. The model developed by Johnson’s study, which could include lessons learned from various locales in the coming years, will be helpful to water managers and governments – large and small – in the decades ahead.

Johnson’s research looks at “agent-based” perspectives and approaches, which analyzes how agents – farmers, irrigation district managers, urban population and governments, for example – make decisions on drought management. It also documents details, such as soil water calculations, contracts between farmers and irrigation districts, well permit approvals, harvesting decisions, crops sales, cities’ water rationing plans, water pricing, flow regulations and much more.

It is so intricate that policymakers or other researchers who use the model can identify red flags or risks that may apply to them as they develop strategies to combat drought in their own regions.

Johnson’s study already has an international flavor. While he conducts research in the Fresno county city of Kerman, he also is collaborating with researchers at the Institute for Environmental Studies (IVM) in Amsterdam on a larger study focused on the applicability and usefulness of the socio-hydrological agent-based models. Other partners in Kenya and Italy are testing cases focused on drought and flood risk management for populations with different climates, technologic constraints and cultural practices, said Johnson.

Co-researcher Marthe Wens, PhD, a scientist at the Vrije Universiteit Amsterdam member of the Water and Climate research group in the Institute for Environmental Studies at the Free University of Amsterdam, is currently in drought-stricken Kenya using and adding to the agent-based model.

“Food production in Kenya depends heavily on smallholder rain-fed agriculture; but subsistence farmers are challenged to match erratic rainfall with crop water requirements,” she noted at the American Geophysical Union meeting in December in Washington, DC. “Increasing climate variability and changing socio-economic conditions are expected to exacerbate this agricultural drought risk and aggravate local food security issues in the coming decades.

“Strategies to decrease agricultural water deficiencies are widely adopted, and more field and community scale climate-smart measures can be expected to emerge. While these adaptations affect vulnerability, exposure and drought propagation, only a few drought risk models incorporate dynamic human adaptation,” she noted.

Johnson’s agent-based, socio-hydrologic model may indeed be a solution to the climate change puzzle.