This week’s episode is the fourth in a multipart series called Climate Hits Home, in which guests discuss the effects of climate change on cities and towns in the United States and how local communities are addressing those effects. In this episode, host Kristin Hayes talks with Lisa LaRocque, sustainability officer for the city of Las Cruces in New Mexico, about how urban infrastructure can intensify heat. LaRocque discusses the ways in which climate change affects temperatures in urban areas, how extreme heat disproportionately impacts certain communities, and the methods applied by Las Cruces and other jurisdictions to mitigate the risks of urban heat islands.
Listen to the Podcast
- Heat islands happen when urban infrastructure traps heat: “Urban heat occurs when cities replace natural land cover with dense concentrations of pavement, concrete, and buildings that absorb and retain heat … When you have these urban designs that create a dense collection of heat-retaining surfaces, they bake the environment day and night. These surfaces are impervious, which means that water can’t pass through them. Heat is absorbed and slowly radiates out.” (3:08)
- Temperatures vary among Las Cruces neighborhoods: “In our latest study with the National Oceanic and Atmospheric Administration, we had nine teams concurrently traveling around predetermined routes in Las Cruces to collect the ambient temperatures … The low-income neighborhoods in the center of the city consistently experienced higher temperatures than the affluent neighborhoods … At 3:00 p.m., frontline communities experienced 112°F, and affluent neighborhoods experienced 103°F. The areas I’m describing represent about 25 percent of our population. This is a serious issue.” (10:33)
- The urban heat island effect can be mitigated through indirect solutions: “Although this doesn’t sound like heat mitigation, the more we stop using fossil fuels and shift to efficient, well-insulated systems, the more resilient we will be during extreme heat events.” (14:38)
Top of the Stack:
- Planning for Urban Heat Resilience by Ladd Keith and Sara Meerow
Kristin Hayes: Hello and welcome to Resources Radio, a weekly podcast from Resources for the Future. I’m your host, Kristin Hayes. Today we’re continuing our multi-episode Climate Hits Home series on how changing climate conditions are impacting communities in the United States.
This episode’s topic is on the urban heat island effect and how to reduce heightened temperatures in urban areas—a long-time consideration for cities, but one of increasing importance in the face of even hotter temperatures. I’m pleased to be speaking about this topic with Lisa LaRocque, who is sustainability officer for the city of Las Cruces in New Mexico. As you can imagine, Las Cruces is no stranger to dealing with heat, but, as temperatures are predicted to rise even further in the face of a warmer climate, strategies to reduce those urban temperatures become even more important. Stay with us.
Hi, Lisa. Thank you so much for joining me today on Resources Radio and for continuing our Climate Hits Home series with us.
Lisa LaRocque: Thanks for including me. I’ve been an avid listener, and it’s a great series.
Kristin Hayes: We always like to start with a get-to-know-you question for our guests. I’d welcome you to say a bit more about your background, but, before I do that, I’d like to ask you what I’ve been told is a typical opening question among folks from New Mexico—red or green?
Lisa LaRocque: I’m partial to green, but sometimes I go Christmas. We’re talking about red and green chili, which is our most popular food source. A lot of people can’t live without it. That’s actually our state question. We also are the first state in the nation to have an official state aroma, and, not surprisingly, it’s roasting green chilies. It’s an important question and smell.
Kristin Hayes: Is it a polarizing topic? Do people fall distinctly into red or green camps?
Lisa LaRocque: Not at all. It depends on the food choice.
Kristin Hayes: Now that we know that you’re potentially Christmas but have likes for both, can you tell us about your professional background?
Lisa LaRocque: I’ve been working in the city for 10 years in sustainability and have done other projects before that with equity and environmental issues. This all kind of melds together. It’s been amazing to watch the progress that’s happened in the last 10 years, and I’m hopeful for what is in store for us in the future.
Kristin Hayes: Let’s dive into our conversation on what is often called the urban heat island effect. I think it’s fairly widely known that urban areas often run several degrees hotter than the suburban, exurban, or rural areas that are around them. Can you talk us briefly through why that is?
Lisa LaRocque: Urban heat occurs when cities replace natural land cover with dense concentrations of pavement, concrete, and buildings that absorb and retain heat. Our urban designs have compounded the effects in about three different ways. When you remove trees, grasses, and other natural waterways that could have a cooling effect on the environment for free, you lose the shade and impact on cooling other surfaces and the evapotranspiration when plants give off moisture.
Together, these two natural surfaces can reduce temperatures by 25°F or more. The other problem is that, when you have these urban designs that create a dense collection of heat-retaining surfaces, they bake the environment day and night. These surfaces are impervious, which means that water can’t pass through them. Heat is absorbed and slowly radiates out. All of the mechanical devices, like heaters, air conditioning, condensers, and vehicles, are putting out waste heat, too—and I haven’t even touched on the dark colors of asphalt and tar-papered roofs or on the huge swaths of parking surfaces.
The last problem is that all this infrastructure lasts a long time. Think about buildings that are easily around for 50 years or more and roads that often get expanded. All of these make the urban environments hotter, and then the environment sprawls and becomes more urban. It’s a big problem to fix.
Kristin Hayes: From the reasons you just shared with us, it sounds like urban heat islands are not explicitly caused by climate change, but they would be exacerbated by it. There’s more heat coming into these cities, which is continuing trends that happen based on the built environment that you described. Is that a fair assessment, or is anything more you’d want to add about that relationship between a hotter climate and hotter cities?
Lisa LaRocque: That is a fair assessment. In fact, this series really highlights how local environmental challenges like flooding, drought, or urban heat become challenges on steroids when climate change is added to the mix and magnifies the problem. Twenty-five years ago, we could count on 1–3 days of extreme temperatures over 105°F. By midcentury, we’re expecting a month; by the end of the century, we’re expecting three months.
It’s not a momentary discomfort. Those are impacts that influence the amount and cost of energy we use, our water supply, the length of our agricultural seasons, air pollution, heat-related illnesses, and mortality as consequences of this heat. Mitigating urban heat can help our city adapt to climate change. Even though urban heat islands are a local problem, they can have a big impact on global issues.
Kristin Hayes: This is reminding me of the previous episode that I recorded for this Climate Hits Home series, where I had a chance to speak with a contact in Phoenix about water availability and drought. One of the things that she noted that I found interesting was that Phoenix is ahead of the game in knowing how to manage water scarcity, because it’s a fact of life in the desert. Would you say the same thing about heat in a place like Las Cruces, which is hot in general? As heat increases, do you feel like you have a leg up in addressing the challenge of urban heat islands?
Lisa LaRocque: I wish the answer was yes, but I don’t think it is in this case of heat. Whereas the importance of water in a desert environment is specific to context—you have to have the water—building in an urban environment has always been more strongly related to national trends. The areas where we are experiencing urban heat are a product of old urban design principles, old building codes, and a lack of appreciation of nature’s services. Communities that were built over 50 years ago or more didn’t pay attention to the same things. They had a different mindset about energy efficiency, design, mobility, parking lots, shopping experiences, walkability, and green space. We didn’t experience the environment when we were in a car or an air-conditioned house.
Today, we are used to this chronic, but variable, amount of heat. Now that these zigzag graphs that we’re used to and say it’s hot or hotter have tilted up towards even higher temperatures, it’s hard to see it as something different. I don’t think we have internalized what it will mean to have 1–3 months of significantly higher temperatures, especially in terms of energy costs, pollution, and health. A problem globally is that we’re not ready for the fact that it’s already here.
Kristin Hayes: I want to ask you about another thing that I know Las Cruces has done, and this speaks to a point you just made about looking at hotspots and where the heat is most prevalent. My understanding is that you’ve undertaken some interesting mapping exercises that look at where that heat is most severe in the urban core. Can you tell us just about that research, how it started, how you did the mapping, and what you found?
Lisa LaRocque: I’ve teamed up with university climate centers and national agencies like NASA and the National Oceanic and Atmospheric Administration. And we worked with the latter on this particular study that you’re talking about. In general, these studies have been invaluable at providing the data we need to justify practices that help us become more resilient and highlight that the new hot is not the same hot.
In the latest study that we did with the National Oceanic and Atmospheric Administration, we had nine teams concurrently traveling around predetermined routes in Las Cruces to collect the ambient temperatures at 6:00–7:00 a.m., 3:00–4:00 p.m., and then 7:00–8:00 p.m. to see how temperatures varied around the city at different times of day. The low-income neighborhoods in the center of the city consistently experienced higher temperatures than the affluent neighborhoods. To put this in context, when it was 3:00 p.m., frontline communities experienced 112°F, and those affluent neighborhoods experienced 103°F. The areas I’m describing represent about 25 percent of our population. This is a serious issue.
Kristin Hayes: What are some of the factors that lead to those differences? Is it tree cover? Is it differences in surfaces? What’s showing up more in those lower-income areas that’s perhaps not showing up—or vice versa—in those more affluent areas?
Lisa LaRocque: I think it’s all of the above. There are fewer trees. There are a lot more impervious surfaces. People don’t have enough parking spaces, so they will park on the front of their property and put concrete or asphalt there. The houses are less well insulated, so they radiate off more heat. It’s a combination of factors.
Kristin Hayes: This might be a good segue to transition from talking about the problems, which you’ve done a great job of laying out, to thinking about solutions. We started referencing a few things around shade and reducing impervious surfaces. Let me turn to you and ask about solutions that Las Cruces has been employing. Here in a place like Washington, DC, we talk a lot about the role of parks and green space, so one thing in particular I’d like to ask about is how that plays out in a desert environment.
I’d love to hear more about residential versus commercial buildings—are there different strategies there? Could you talk a bit about how your strategies are actually evolving as you think about temperatures rising even further?
Lisa LaRocque: There are some universal practices that we have or are putting in place in landscaping, but we still have a long way to go. We only have four percent tree canopy. Out in the East, you’re probably shocked to hear that. In part, that’s what defines a desert. But we can have more trees, and we’re following Albuquerque’s lead to treat trees as a public good. The city would provide trees to residents and other land landowners, and nonprofits could help with green infrastructure, which means harvesting stormwater or finding ways to collect water to be able to irrigate those trees. Of course, they’re native trees that don’t require a lot. Landowners would be responsible for taking care of them.
We’ve also started using pervious pavement on some of our trails and cool reflective green sealant on our bike lanes to reduce surface temperatures. For those folks who want to go out and walk or ride a bike, we’re trying to help them out. We also are making some headway on our building sector with mandatory new construction codes that require buildings to be electric-ready with higher insulation and upgraded electric panels. We also have volunteer stretch codes that move you to high-efficiency, all-electric buildings that are deliberately aligned with the Inflation Reduction Act rebates and tax credits, for a real carrot for people to do things. Although this doesn’t sound like heat mitigation, the more we stop using fossil fuels and shift to efficient, well-insulated systems, the more resilient we will be during extreme heat events.
Kristin Hayes: Now, I have a special guest joining me: the producer of Resources Radio and editor of the award-winning Resources magazine, Elizabeth Wason. Welcome.
Elizabeth Wason: Thanks. It’s nice to be here at the mic with you.
Kristin Hayes: I see you brought something. Is that the latest issue of the magazine?
Elizabeth Wason: It sure is—hot off the presses. We’ve got articles in here about the Energy Insights Conference that Resources for the Future (RFF) cohosted, the Net-Zero Economy Summit celebrating RFF’s 70th anniversary last year, and a whole lot more.
Kristin Hayes: How can listeners get their hands on that magazine?
Elizabeth Wason: If listeners make a gift to RFF in any amount, they’ll receive a print subscription to Resources for the next year, including this May issue. That’s three issues of the magazine delivered right to your doorstep. Just visit rff.org/donate and make your contribution today.
Kristin Hayes: I can hardly wait to dig into those pages, but, for now, let’s get back to the show.
Lisa, this is all super interesting, and I want to circle back now to something that you mentioned in an earlier response, and that’s disadvantaged communities. We’ve talked about this in every one of the episodes in this series—as with most if not all climate-related impacts, the burdens of heat are often felt most heavily in disadvantaged communities. It sounds like that is the case in Las Cruces, when it comes to these urban heat island effects. Are there specific measures and solutions that you’re implementing that try to ensure a more equitable response to those high temperatures?
Lisa LaRocque: This is something near and dear to my heart. We are working on a special program to deal with retrofitting the older homes that I described in the beginning of this segment. Those are particularly an issue for our frontline communities that own or rent these houses. Sadly, we’ve uncovered many systemic inequities that we want to address. I know this is the positive part of your segment, and I will promise to highlight some good outcomes from this.
The places that people live that we’re talking about will not meet today’s building codes, and we don’t give a lot of thought to the point that they’re in older houses. Those standards were much more lax compared to the new standards that we’re proposing. There’s inadequate insulation; single-paned windows; and heating, ventilation, and air-conditioning (HVAC) systems that are near the end of their life cycles. Houses with these characteristics are the only homes low-income folks can afford. With this comes a long list of deferred maintenance and high utility bills due to the inefficient systems.
They’re carrying all of these problems on their shoulders from the neglect that happened from previous owners. A large part of the low-income residents are considered house burdened, which means that they pay over 30 percent of their income on mortgage or rent with utilities, which make up a big portion of those costs.
50 percent of our frontline communities rely on what are called evaporative coolers, which are wet filters that you pass air through and that lower the temperature. I know in a human environment you think I’m crazy, but that’s what we do. But the problem is that with urban heat continuously bringing in hotter temperatures, coupled with the extreme heat events that we have, all happening during the summer, which is a rainy season, this low-tech solution is no longer working. It will only decrease temperatures by about 10°F. That means houses are still in the 90s.
This circles back to the whole idea that you have to have a well-insulated house in order to keep it cool because the temperatures outside can come in and heat it up. Those residents with air conditioning and high utilities often don’t use their HVAC systems to avoid shutoff fines, and that puts them at a health risk. We’ve gone from saying, “It’s a hot day,” to “These people are in a constant health risk,” because it’s very draining to your body to try to have to be cool all the time if you don’t have those HVAC systems.
Now, for the good news, thanks to the Inflation Reduction Act and other state and local programs, we’re focusing our attention on a scalable retrofit program that will reduce energy burdens where we’re going to replace the HVAC systems with high-efficiency heat pumps that heat and cool.
We’re upgrading electric panels, and we’re developing new workforce opportunities for those that are most impacted. If bills are not low enough, we also have a new community solar program that has a special rate for low-income folks so that we can reduce their utility bills by 30 percent more. These improvements not only are good for equity socially, but they also put equity monetarily in the house. Plus, we train a new workforce.
The best thing is that this program is being cocreated by the community. We’re getting a real insight as to what challenges they face in terms of the programs that currently exist, how they’re not meeting their needs, and what they’d like to do it. It’s been a rewarding process to go through and develop this program.
Kristin Hayes: One thing I’m hearing, too, is that I think it’s probably fair to say that it’s rare where you actually have the resources and the opportunity to address so many factors that contribute to this all at once. You can replace heat pumps, have funds left over to improve insulation, and also tackle multiple causes at the same time. It just sounds like a promising moment to look systemically at some of these challenges.
Lisa LaRocque: I am feeling so grateful that all of these opportunities have come before us. The Inflation Reduction Act is a godsend for us to be able to address this. We have a university that works in a lot of areas of energy efficiency and solar, and they can help. We’re collaborating with a lot of different groups. The weatherization programs can help with insulation, the Inflation Reduction Act can help with heat pumps, and community colleges can help with the workforce. It is a group effort, and I see the potential will be significant if we can get it scaled up in time for the money to be available to us.
Kristin Hayes: That brings me to my last substantive question, which is more like four questions in one, but I’ll try to be concise.
I want to ask about connections with other jurisdictions, because something we’ve talked a lot about in this series is that, in many ways, each of the place-based realities that we’re talking about have unique infrastructure and climate and population compositions. Dealing with some of these resiliency considerations needs to take these local conditions into account. That being said, there’s support from other jurisdictions through learning or through dollars that can be useful. It is a partnership between this local learning and potentially gathering the best of the resources from around. You mentioned the Inflation Reduction Act and a number of other programs available to you.
So, I wanted to ask one other specific question, which is about the Federal Emergency Management Agency (FEMA) and whether FEMA in particular is potentially moving towards funding for resilience investments, as well—not just recovery after bad things happen, but preparing in advance.
You also mentioned Albuquerque, and I wanted to understand what you’ve been able to learn from other jurisdictions around you that you’ve incorporated into your work there in Las Cruces.
Lisa LaRocque: First of all, the federal and state agencies are stepping up to the sustainable and equitable practices—especially those that are outlined in the Justice40 Initiative that accompanies all the grants in the federal jurisdiction. Everybody is listening to the call to action and wanting to help and support each other. There’re lots of ways that we can get help. We’re all committed to the action. I see things really blossoming, and groups like FEMA are a great example, because initially they were more of a reactive group, and you can understand why—there are lots of emergencies.
But they’re now looking at upstream solutions about how communities can be more resilient. I appreciate that, and I think it’s a new relationship, because they are poised to do it but haven’t been involved with people who think like that. Bringing the sustainable community to FEMA will be an interesting way to reframe how we approach things for long-term benefits.
Toward your questions about applicability, I think that one of the things that we all benefit from is hearing the challenges that everyone is facing and the strategies that people are using, no matter where they are, because you can compare and contrast them to your own situation or figure out how you want to morph them. No matter whether I’m talking about Albuquerque, or someone in Arizona or Norfolk, I hear lessons all along from these folks, and I’ve tried to distill them to three lessons to be more succinct.
One of them is that these issues that we see locally and globally are caused by us not living within the ecological systems that the earth has in place. Think of material cycles and the laws of energy or thermodynamics as guiding principles. When we’re emitting too much greenhouse gas into the atmosphere, you see the consequence. How do we keep those cycles the way that the earth intended them? How do we look at energy so that we can be as efficient as possible by not having it convert to 10 forms before it gets to you? Those are all lessons that we need to learn. There’s humility we need to feel in order to move forward on how we’re solving problems.
The second thing is, if you have had local issues that you haven’t addressed with these ecological services, you should get going, and there is a good chance that things are going to get worse. I have seen so many patterns change with more extreme events, and people say, “It never rained this early,” or, “The winds never blew this hard,” or, “Boy, the amount of fire tinder is growing.” Those are all red flags that we need to pay attention to, and there’s no benefit of an I-told-you-so moment.
The third thing, which is coming home to me as I work on this project with retrofitting and cocreating with the community, is that as you unpack things, you will find inequities. This is a real chance for us to learn, do things better, right our wrongs, and question the fairness of having certain populations shoulder things in a much harder way. It’s going to get worse.
I want to be positive—I think there’s opportunities to do things better.
Kristin Hayes: Lisa, I appreciate the time you’ve taken to share a vision of what Las Cruces is doing in this area. I’m sure it is a place where you will talk about heat many more times, but I appreciate you taking the chance to talk about it with me today.
Lisa LaRocque: Thank you for having me. I really appreciate it.
Kristin Hayes: Of course. Let me ask you our standard closing question—Top of the Stack—and I would welcome any recommendations you might have for our listeners. It can be content of any type that you might want to suggest that folks engage with. What’s on the top of your stack?
Lisa LaRocque: I’m very pragmatic, so I wanted to give a shout-out to my friend Ladd Keith out of the University of Arizona. He and Sara Meerow have written this book called Planning for Urban Heat Resilience. They did that in 2022, and it is a great resource. It provides a rich background. There’s a planning framework and a catalog of comprehensive approaches to heat mitigation and management for folks in a host of agencies and sectors. It really looks at urban heat resiliency for the long term. Boy, if you want a fresh idea or to be reminded of a good old one, it’s in that book.
Kristin Hayes: We’ll definitely put a link to that on the website so that folks can check it out. Thank you again, Lisa. It’s been a pleasure.
Lisa LaRocque: Thank you so much for doing this series. It’s great.
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