Heat Waves Amplify Existing Inequities. Meet the Researchers Working to Change That.

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• Sara Bock- [email protected]

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At the UC San Diego School of Global Policy and Strategy, environmental scientist Jennifer Burney is working to understand how and why certain racial and ethnic groups in the U.S. face higher exposures to urban heat. Her work helps inform policies and interventions that communities can put in place to help alleviate these disparities and mitigate the severe consequences of extreme heat exposure, which range from premature births and health complications to lower test scores and decreased productivity.

Burney, who serves as the Marshall Saunders Chancellor's Endowed Chair in Global Policy and Research, co-authored a 2021 studywith postdoctoral researcher Susi Benz, which found that low-income neighborhoods and communities with higher Black, Hispanic and Asian populations experience significantly more urban heat than wealthier or predominantly white neighborhoods within a vast majority of populous counties in the U.S.

These disparities can in part be attributed to a history of explicitly discriminatory housing policies such as redlining. However, Burney says her research has found that this history doesn't tell the entire story.

"There's pretty strong evidence of policy failures even in new cities that never experienced redlining for example-there is a race and ethnicity gradient in who faces a larger urban heat burden," said Burney. "I think what people found most interesting about that study was that even when we adjusted for income, those racial and ethnic disparities in urban heating persist. There's evidence of a bigger policy failure around heat and who's exposed and who's not."

By working to better understand the urban burden of climate change-which has included creating an interactive map of the U.S. that combines urban heat trends with demographic data-Burney hopes that her team's findings can be used to inform policymakers and local leaders on how to effectively implement interventions such as urban greening and cooling centers that will help vulnerable populations cope on the hottest of days.

Advocating for worker protection

What is the impact on workers in agriculture, construction and manufacturing when heat waves become more severe, and their working environments lack climate control?

Joshua Graff Zivin, a professor of economics and the director of the UC San Diego School of Global Policy and Strategy's Peter F. Cowhey Center on Global Transformation, has dedicated much of his research to answering this question. An internationally renowned economist, Graff Zivin has examined the impact of extreme heat on labor in what he calls "exposed industries"-jobs often done outdoors or in non-air-conditioned settings.

In a 2021 paper, Graff Zivin and an international team of colleagues looked at how very hot days affect the amount of time people spend working, especially in these exposed industries. Researchers used data from 2003 to 2018 to see if high temperatures caused people in these jobs to work less and found that during periods of economic growth-like before and after the Great Recession-workers reduced their work hours on days when the temperature exceeded 90 degrees. However, during the recession, when jobs were scarcer, workers did not reduce their hours, even on hot days.

Graff Zivin emphasizes that this is not just a matter of quantifying hours lost, but also considering how productivity declines due to factors such as lack of sleep and physical strain in extreme heat.

The study predicts that as climate change causes more frequent hot days, workers in these "high-risk" jobs will continue to lose work hours. By 2090, this could mean up to $80 billion in lost wages annually across the U.S. if greenhouse gas emissions remain high. The research suggests that planning for these changes is important to protect workers and reduce the financial impact on them and their families.

These findings also highlight a significant inequity, Graff Zivin explains, noting that Black and brown communities bear a greater burden since they are overrepresented in industries where workers are regularly exposed to extreme heat.

To address these disparities, Graff Zivin has applied his knowledge beyond academia, advising on policies that could make a real difference for vulnerable workers. He recently served as an advisor to Occupational Safety and Health Administration (OSHA) in the development of a proposed rule that the U.S. Department of Labor says would help protect approximately 36 million workers in indoor and outdoor work settings and substantially reduce heat injuries, illnesses and deaths in the workplace.

"As long as the climate continues to warm and the U.S. invests in bringing more high-quality manufacturing jobs to our shores, regulations to protect workers could not be more urgent," Graff Zivin said.

Engineering resilience in power grids

When wildfires strike California or extreme heat overloads the grid, public safety power shut-offs can leave low-income neighborhoods in the dark-sometimes for days-jeopardizing the safety and well-being of their residents. These tend to also be the communities where the lights go out first and are the last to come back on.

Patricia Hidalgo-Gonzalez, an assistant professor of mechanical and aerospace engineering at the UC San Diego Jacobs School of Engineering, is determined to change that. With nearly $2 million in climate action seed fundingawarded last year by the University of California, she's leading a project to build more resilient power grids that ensure equitable access to energy during extreme heat events.

Working alongside a team of researchers from UC San Diego, UC Santa Barbara, UC Berkeley, the National Renewable Energy Laboratory, Lawrence Berkeley National Laboratory and GridLab, Hidalgo-Gonzalez aims to help protect disadvantaged communities by strengthening local energy distribution networks and promoting the adoption of distributed energy resources such as solar panels.

The team's strategy is twofold: understand the barriers to adopting clean energy in these communities and develop customized solutions to overcome them. By using community surveys and high-resolution geographical data, her team is working to design optimized microgrid configurations that work in tandem with the broader California grid, enhancing both resilience and equity.

The project also aims to create economic incentives for these communities to adopt distributed energy resources, like solar power, which have been slow to take root in many disadvantaged areas. By fostering local resilience and equitable access to energy, Hidalgo-Gonzalez hopes to prepare vulnerable communities for the escalating impacts of climate change.

"This project has been very exciting to work on for different reasons. On one hand, given that it is action-oriented, we hope that our findings will be able to inform policy and new financial structures to deploy and operate distributed energy resources that are grounded in the reality the California Public Utilities Commission operates," said Hidalgo-Gonzalez. "On the other hand, having equity at the forefront, it is also enabling us to focus on solutions that will support historically marginalized communities that may have been left behind when it comes to grid upgrades, resiliency, deployment of new technologies, and electrification. All of this, being aware and resilient to extreme weather events. Another aspect that has been very rewarding for me is the diverse and strong team we have."

Preparing communities for heat and smoke risks

During extreme heat events, people experiencing homelessness or who have certain chronic illnesses or psychiatric conditions are among those who face heightened risks to their health and safety.

What are the social justice implications of the growing threats posed by extreme heat? And what changes can be made to make our communities more resilient while protecting the unhoused and the most vulnerable among us?

These are the questions that Tarik Benmarhnia, a climate change epidemiologist at UC San Diego's Scripps Institution of Oceanography, is working to answer. His research aims to deepen our understanding of how environmental and social determinants affect population health and equity-and to develop strategies that effectively minimize these impacts.

Earlier this year, Benmarhnia and postdoctoral scholar Chen Chen, alongside colleagues from Scripps and the UCLA Fielding School of Public Health, co-authored a studywhich found that extreme heat and wildfire smoke-more frequently co-occurring due to climate change-together cause increased damage to people's hearts and respiratory systems. What's more, the study found that their synergistic effects disproportionately cause harm in ZIP codes where residents were likely to be poorer, people of color, living in higher density and less likely to have health insurance.

"This work is critical to designing adaptation strategies and targeting the most vulnerable communities while considering the co-occurrence of climate hazards," said Benmarhnia.

Through this work, as well as through interdisciplinary collaborations within the NSF-funded SoCal Heat Hubat UC San Diego, Benmarhnia aims to provide actionable findings that can inform emergency room preparedness, improve early warning systems and increase the number of cooling centers in the communities that need them most. He hopes to one day see an influx of cooling centers that also provide access to social services, mental health care, diabetes prevention and more-which he believes could be key to tackling the compounded risk factors that exacerbate the impacts of extreme heat in high-risk areas.

Learn more about research and education at UC San Diego in: Climate Change

Topics covered:

• Climate Change
• Extreme Heat

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