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Reimagining cities’ and our roles in the fight against climate change

Reimagining cities’ and our roles in the fight against climate change

portrait of Joseph Karanja in front of a map

March 18, 2022

ASU student seeks to better understand which communities are most at risk from heat-related threats

There’s no debate, heat-related illnesses are common during the summer in Phoenix.

Nearly 3,000 people visit Arizona emergency departments each year with heat-related illnesses. In the past decade, heat-related deaths have increased more than 180%. In 2020, there were 323 heat related deaths in Maricopa County. 

Cities like Phoenix are relying on current heat-vulnerability models for mitigation strategy decision-making that, while helpful, are fraught with limitations — due in part to the way they are constructed and the data used — and risk, leaving out some of the most vulnerable populations in need.

Joseph Karanja, a graduate candidate in the School of Geographical Sciences and Urban Planning, is conducting research in order to create a holistic view of how heat disproportionately affects specific communities around Phoenix to better understand the city’s potential to arm the most vulnerable against the looming heat-health threats.  

“Comparing outcomes in Maricopa County, homeless account for about 40% of the deaths, yet census datasets (the information that powers current heat-health modeling) cannot account for that population,” Karanja said. “We are simply relying on these data because of the absence of an alternative. I challenge that. I want to prompt people to think of alternative data sets and alternative ways of thinking.” 

Karanja’s research not only examines which variables should be included in heat-vulnerability modeling, but he also uses statistical techniques to create new ways to combine disparate information to gain new perspectives and insights into how communities are dealing with heat stress and heat health impacts. 

Karanja recently presented a commentary paper titled “Methodological Rationale for Heat Vulnerability Indices as Predictors of Heat-Health Outcomes” at the American Association of Geographers annual meeting in February, discussing a portion of this research.

“There has been an increasing amount of work, globally, focused on improved understanding of what variables serve as the best metrics for assessment of heat-health outcomes,” said Matei GeorgescuCo-author of the study is Judith Sullivan, an associate professor at the School of Geographical Sciences and Urban Planning. “Where is exposure to extreme heat greatest? Which populations are most susceptible to extreme heat temperatures? What social and physical barriers must be removed in order to increase the ability of people to adapt to extreme heat?

“Joseph’s work directly tackles this critical research gap by focusing on simplifying the overall approach through a re-conceptualization of the very methodological aspects that are the foundation for heat vulnerability indicator development. His work is helping to reshape the very foundation that is required for characterizing heat-health outcomes across global cities.” 

portrait of Joseph Karanja in front of a map

Joseph Karanja.

Reimagining complex processes and unifying data 

At the heart of his research, Karanja is creating a new composite heat-vulnerability metric — a metric that combines not only biophysical (heat) data, but also socioeconomic data from various sources to give researchers and policymakers a finer lens into who is most heat-health vulnerable.

Karanja explains that by coupling these metrics and finding the optimal way to meld them together, his research hopes to capture the overlooked nuances of how heat disproportionately affects communities, which include: differences in how heat exposure impacts people living in different geographical parts of the city that may or may not have infrastructure that can reduce heat impact; and differences in income and people’s ability to have reliable access to air conditioning or beneficial tree canopy in their yards. 

“We need to continuously look at the current data, new data; evaluate how we are continuously constructing metrics; see how those metrics influence health outcomes and inform decision-making; and at the same time, (think about) how do those health outcomes inform the construction of the metrics and the collection of data in the first place,” he said. “We’re creating a feedback loop system.” 

Karanja’s research not only interrogates the metrics we currently use, but evaluates our current approach to the process, reimagining it as an evolving cycle that will continue to be refined as more information becomes available. 

“I have never met a student with a greater desire, an unquenchable thirst, to learn,” said Georgescu, who serves as Karanja’s academic adviser. “He is undaunted by challenges and is unfazed at immersing himself in completely new fields. Joseph is a future global superstar. I am thrilled to be a part the next three to fourth years of his Arizona State University experience.

“I am equally excited to see where his passions and thirst for making a global difference lead him down the road, beyond ASU.” 

The world is your oyster 

Karanja’s research and educational drive have ties to a humble beginning. 

A native of Webyue, Kenya, a modest town near the eastern border of Uganda with makeshift settlements and a sugar cane plantation, Karanja says it’s his community that rallied around him and enabled him to pursue his educational endeavors.

“I was brought up by a single mother, so my story is being part of a lot of struggle in Kenya,” Karanja said. “Basic education was not free at the primary school level and in secondary school level. It’s actually the community that came together and sponsored me to get to high school.”

He went on to receive a bachelor’s degree in Kenya from Kenyatta University with a focus on environmental planning and management, focusing on rural neighborhood planning, regional and urban planning, and governance issues that relate to planning and design. He believes his current work in analyzing heat vulnerability is a tool for better understanding society. 

“When I came to the U.S., I really wanted to study urban planning, but I realized having been brought up in squalor-like settlements, there are so many urban challenges,” Karanja said. “If you are to solve challenges tied to heat, to some large extent, you are dealing with climate change problems associated with population growth and rapid urbanization.

“You’re, in a way, solving so many problems just by looking at heat in all its multi-dimensionality.” 

The right place to begin 

Karanja hopes that his research not only will provide the foundation for future heat vulnerability models to better characterize heat outcomes in cities but also that he will be able to conduct similar research back home in Kenya. 

He credits his supportive environment throughout his academic career for the opportunities he’s had and the impact he plans to make. 

“I want to thank people who have been significant in my life, believed in and nurtured me,” Karanja said. “I’ve had a very supportive environment, and to provide some contribution to the scientific community towards the construction of heat matrices, I believe here at Arizona State University is the right place to start.”  

Top photo courtesy depositphotos.com

David Rozul

Media Relations Officer, Media Relations and Strategic Communications


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