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UCSD Study Finds Some Urban Neighborhoods Are Hotter Than Others

 July 13, 2021 at 10:18 AM PDT

Speaker 1: 00:00 As the summer heats up in San Diego, not all city neighborhoods are experiencing the same hot temperatures, a new study from UC San Diego finds that low income neighborhoods and communities with higher black, Hispanic, and Asian populations experienced significantly more summer heat sometimes to a dangerous extent. The disparity is baked into urban planning and density here in San Diego. And in cities across the country. Joining me is Jennifer Burney, co author of the paper on heat in poor and minority communities in us cities. She's an environmental scientist and associate professor at UC San Diego. Jennifer, welcome to the Speaker 2: 00:41 Program. Thank you for having me. How Speaker 1: 00:43 Significant was the temperature difference between wealthier white neighborhoods and lower income minority neighborhoods that you observed in your study? Speaker 2: 00:53 Yeah, so, um, this can be, uh, up to a degree or two Celsius between different types of neighborhoods. And again, cities tend to be on average, a warmer than their more rural surroundings. Um, one thing I'll say is that even in cities that are cooler than their surroundings, um, that happens in more desert areas and San Diego is actually a place that's a little bit cooler in our city than the surroundings, but even in cities with sort of urban cooling those, um, lower income and minority neighborhoods actually have less cooling than the wealthier whiter neighborhoods. The reasons Speaker 1: 01:31 For that, what kinds of things cause these differences in temperature? Speaker 2: 01:36 Yeah, so at a very physical level, it's the structure of cities. So, so how we transform the surface of the earth when we urbanize, uh, actually changes the energy balance, uh, you know, what happens to sunlight as it, as it comes in and, and hits the surface of the earth. So we see, for example, if you have less vegetation, such as, you know, you sort of clear native habitat to, to build a development, um, that vegetation provides cooling through evaporate, evaporation of water vapor, transpiration of water. And so, uh, you know, if you lose the vegetative cooling that can contribute to warming, um, if you have really high density buildings that trap heat, that's another factor, uh, depending on kind of the color of the reflectivity of the city, the materials that are used, those also affect this energy balance, um, as does just the density of people, uh, and sort of heat produced by people in their activities. So those are the main factors, but that's not, I don't think that's really your question. That's kind of the physical story. The, you know, the sort of, how did this happen question, I think is really one about how urban policy and planning has proceeded occur across our country. So do we view, um, access to greenspace as a luxury, or is it something that everyone should have access to these kinds of decisions about sort of who has access to what spaces, um, it's kind of sum total of urban policy, what Speaker 1: 02:59 Areas within San Diego county stood out to you in terms of these temperature disparities? Speaker 2: 03:05 Yeah, so we see higher urban heating in San Diego county in areas like Lamesa Rolando park, El Cahone Tierrasanta, um, Kearny, Mesa, even thinking more coastally national city, you know, warmer than other similar coastal areas. Um, so can people Speaker 1: 03:26 Look up how their area compares to those Speaker 2: 03:29 Around them? Yes, they can. So we have built, uh, an app that is accessible to anyone with a web browser and an internet connection, and they can look up, um, any city in the U S and really their neighborhood, their, their census tract, um, within, uh, within a city and see how it compares to, um, surrounding areas within the county and nationally Speaker 1: 03:53 Being exposed to higher temperatures have consequences like in school Speaker 2: 03:58 Or so we know that humans in general, uh, respond pretty poorly to, to heat exposure. It's true that we can adapt to some extent, but high temperatures are really dangerous, uh, particularly for the traditionally vulnerable populations, kids elderly. And so, yeah, access to this kind of excess urban heating can be really dangerous from a, from a health perspective. Like we always think about this during heat waves, right, when this is kind of amplified, but this is also a slow moving phenomenon. So there's a direct kind of health impact. There also are less obvious productivity impacts. So we know that high temperatures are associated with, for example, children doing less well on exams in school, or with workers, uh, having lower productivity in a bunch of different ways. But, um, scholars have kind of recently been able to really measure it's something we all feel right. Speaker 2: 04:58 Less productive when it's happening, but it's really true. And it matters for the economy of the city. What can cities do to lessen these differences? I think the two big levers on the system are vegetation and sort of building structure and how buildings are able to sort of trap or, or not trap heat. Um, so, uh, on the vegetation side, really, I think thinking about vegetation as a cooling tool and making sure that we build in green space really as a health, uh, almost as a health factor in our cities is one. And then really thinking about building design that allows for, um, cooling both within buildings, right? Sort of not, not trapping heat within buildings, but also, uh, buildings that don't trap heat in city corridors and things like that. So a lot of really interesting architectural and urban planning, uh, could go into how we think about our, our building structure as well. And Speaker 1: 05:55 How would you like to see the information in this study Speaker 2: 05:57 Used to me, the thing that jumped out with this study is that across all these different regions that have very different histories and very different geographies, you see this very persistent effect, right? So in particular that low-income communities and, um, black, Hispanic, and Asian communities are experiencing higher urban heating than their neighboring wealthier and wider communities. And so to me, that suggests really that we've built a world that is viewing kind of access to, to more pleasant, urban spaces as a, either an economic amenity or, um, unexclusive amenity. And I do think that the study points to the need for real rethink about how we're building our cities and, and how that structure could serve everybody more equitably speaking Speaker 1: 06:53 With Jennifer Burnie, co author of the paper on heat in poor and minority communities in us cities. She's an environmental scientist and associate professor at UC San Diego. Jennifer. Thank you. Thank you.

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As the summer heats up in San Diego, not all city neighborhoods are experiencing the same hot temperatures. A new study from UC San Diego finds that low-income neighborhoods and communities with higher Black, Hispanic and Asian populations experience significantly more summer heat...sometimes to a dangerous extent. The disparity is baked into urban planning and density here in San Diego and in cities across the country
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