Lowering the temperature in Southern Nevada... What can be done, and what is being done?

That's this week on Nevada Week.

♪♪♪♪♪ Support for Nevada Week is provided by Senator William H. Hernstadt.

-Welcome to Nevada Week.

I'm Amber Renee Dixon.

The Clark County Coroner says so far this year, heat has played a role in the deaths of at least 63 people, but that number only includes cases in which the person was identified and next of kin was notified.

In 2023 the coroner says heat contributed to the deaths of 307 people, a significant increase from the year before, when heat was a factor in the deaths of 169 people.

So what role can local government play in reducing the harm that heat can inflict?

For that, we turn to our panel of experts.

Marci Henson is the Director of the Department of Environment and Sustainability at Clark County; Marco Velotta is the Chief Sustainability Officer at the City of Las Vegas; Andrew Kjellman is the Senior Director of the Metropolitan Planning Organization at the Regional Transportation Commission of Southern Nevada; and Steffen Lehmann is a Professor of Architecture and Urbanism at UNLV.

Steffen, did I get it right?

-Perfect.

-Okay.

I want to start with you.

You have dedicated your life to this issue of urban development and doing it sustainably.

So of the mitigation methods that exist for heat, what should be the top priority for local government in Southern Nevada?

(Steffen Lehmann) Okay.

I mean, we are living in a desert city.

-Yes.

-We are used to an extreme climate, and now heat is in everybody's mind.

There are four things we should think about: vegetation, materials, color, and shade on all glass.

So let me-- -Can we start with vegetation?

Is that the number one?

-Yes, it is definitely.

We should engage in a huge tree planting program here.

I'm talking about millions of trees, because it is the most cost effective way to mitigate the urban microclimate.

And we have to select trees that are native, not so thirsty, drought resistant, and, for instance, willow trees or ash or mesquite trees, trees preferably with large leaves that cast a lot of shade on the ground to keep the surface of the ground cooler and to keep the urban microclimate cool during the day so we do not have an urban heat island effect at night.

-Will you explain the urban heat island effect.

-Yes.

The urban heat island effect is a phenomenon where you have a hotter area in the city, significantly warmer than, let's say, at the edge of the city in the suburb, because what happens, the city materials, the roofs and facades, start absorbing solar radiation and they trap and they store the heat, so the city becomes a baking oven.

It's mainly a nighttime problem.

And having vegetation, all sorts of vegetation, not only trees, but also community gardens, more Springs Preserves.

We have the wonderful park, but we should have probably 20 of those.

And so all forms of urban vegetation should be integrated in every new project to ensure we keep the city cool.

-Okay.

I want to go with the county first and then the city.

Where is the county on these efforts of vegetation?

(Marci Henson) Yeah, so Clark County has been doing a lot to address impacts of climate change, and particularly urban heat.

As you mentioned, it's a public safety issue.

So one of the things that we've done is Clark County Code requires landscaping when new projects are developed or when there are major land use changes to a project.

And so making sure that projects that are being built in unincorporated Clark County have vegetation and shade trees, in particular, is a requirement for all of those projects.

Last year, we actually also instituted an in-lieu fee program, meaning that if a developer needed any sort of reduction or waiver to landscaping, which can happen sometimes--there are some site designs that do not accommodate large shade trees--that they're paying an in-lieu fee so that we, the County, can use that fee to plant that shade tree elsewhere, and particularly in parts of our community that are disproportionately impacted by urban heat and don't necessarily have the resources to add their own shade trees.

We are also looking at starting a community canopy partnership with the Arbor Day Foundation.

We're getting ready to kick that off in September.

We'll have a tree giveaway, and we'll also be allowing residents to sign up to receive trees direct mail.

And we've been working with all of our partners here at the table.

We're all-- we all have some sort of urban tree canopy shade program, and we're having meetings about those.

-Marco?

(Marco Velotta) The City of Las Vegas has also been working on this for some time.

As part of our 2050 Master Plan, we have looked at the urban heat island effect and the impact, especially on communities where it's been hitting it the hardest.

Bonanza and Eastern is the confluence of not only urban heat, but also socioeconomics and demographics.

There's quite a bit of impact on the east side of the Las Vegas Valley for geographic reasons and then the other reasons.

So we have been investing in the tree canopy in Downtown Las Vegas, East Las Vegas, the Historic Westside, and we'll be continuing to do that as part of our overall goal to plant 60,000 municipal trees over the next 30 years.

And a big way of doing that is our Community Forestry grant that we received from USDA, which will help our neighbors plant trees at their properties throughout the city of Las Vegas.

-So 60,000 trees by 2050, and Steffen is saying millions of trees.

-Easily.

Even more.

Riyadh City is now planting a billion trees in Saudi Arabia.

So I think we can-- the more we do, the better, because it's the most cost effective way.

And 60,000 is a good start, but I think you can never stop doing that.

Every time you cut down a tree, you have to plant two new ones.

So you always increase the cover, and it's the best thing we can do.

-Well, we're going to talk about what's keeping more trees from being planted.

But first, I want to acknowledge that the nonprofit research group Climate Central agrees, trees are part of the solution because they can cool the air and hot surface temperatures, like pavement.

However, recent research shows trees tend to be sparse in lower income neighborhoods.

Here's part of a story Nevada Week did on that last year.

(Lisa Ortega) This is a city of Las Vegas map, and this is where we're going to be planting 250 trees.

-Lisa Ortega, Executive Director of Nevada Plants, knows which Las Vegas neighborhoods lack tree cover.

-Lower income, less canopy.

-And less tree canopy means less shade and hotter temperatures for Las Vegans like Felipe Arellano... (Felipe Arellano) Vegas is being getting really hot, 115 degrees, and we need shade.

-...and Kristyn Dunne and her son.

(Kristyn Dunne) Trees can be a little expensive, and so we were really excited to get a tree that's going to grow really big and give him shade and eventually, you know, make it so he can play outside all year round.

-Thanks to Nevada Plants, Dunne and Arellano each got a tree and irrigation system for $20.

Their East Las Vegas area codes qualified them.

(Chris David) We see a lot of communities in Eastern Las Vegas or Sunrise Manor as well as North Las Vegas that have often 1 or 2% true canopy cover.

Those neighborhoods often have the highest numbers of people in poverty or people of color as well.

On the other side of the coin, the most treed communities, you might not be surprised that those are in those master planned communities of Summerlin and Green Valley.

-Chris David oversees map-based visual storytelling at American Forests, a national nonprofit conservation organization which created the Tree Equity Score tool.

-That's a combination of a measure of need of tree canopy cover that's based on the existing tree canopy cover for your community and a measure of equity based on demographics and heat.

The lower your score, so the further you are from 100, the higher your priority will be.

-We have our drone in an area of Summerlin where the Tree Equity Score is a perfect 100.

You can see the difference in tree canopy here, where, according to the Las Vegas Global Economic Alliance, the median household income is about $111,000.

Compare that to this drone footage from Dunne's neighborhood, where the Tree Equity Score is just 59 and the household income less than $29,000.

Andrew, with RTC, I want to get to you now, because in addition to that map, that Tree Equity map, there is a map that RTC has come out with.

And when was that done, why was it done, and how does it relate to this?

(Andrew Kjellman) So the RTC has done a lot of research in this area.

In 2022 we received a grant from the National Oceanic Atmospheric Administration, and what that grant enabled us to do is actually map urban heat in Southern Nevada.

And so we engaged volunteers.

We had over 300 citizens reach out to the RTC and take part in this program.

On the actual day of the urban heat island mapping, we mapped 28 routes with over 60 volunteers.

And what we found is a lot what that video showed is that heat is not evenly distributed in Southern Nevada.

And so when you look just at raw temperature, the hottest areas of the valley are 11 degrees hotter than the cooler areas.

And when we collected this data, it was in August, so it was monsoon season.

And so humidity was also a factor at that time.

And so when you look at the heat index and factor that in, there was a 30-degree disparity between the coolest areas and the hottest areas.

And so what that means is on a day in August, an area in the east side of Las Vegas, where it's 110, it's 80 degrees in more cool areas.

And so that's a big difference.

And then when you combine that with differences in sociodemographic conditions and the ability to cool oneself, if you have AC, if you can afford it, there's big differences.

And so when the RTC is focusing on our tree planting efforts, our Complete Streets, and our transit services, we're really focusing on these areas that are more affected by extreme heat.

-Will you talk about the Complete Streets?

-So Complete Streets are really roadways that are designed for all users of the transportation system.

So those are drivers, people walking, biking, rolling, and walking to take an RTC bus.

And so it's really ensuring that the facility is designed to accommodate all of the different users of the transportation system.

A big part of that is street trees.

And so street trees make it safer for everyone, because it really helps slow the cars down, and it makes it more comfortable for people walking, biking, and taking transit.

And so when we build Complete Streets, they're really coupled with a lot of street trees.

And so there's examples of this on Boulder Highway.

We're partnering with the City of Henderson on their Reimagine Boulder Highway project.

And then a big project for the RTC is our Maryland Parkway project that we're about to start construction on in August.

And we've added street trees to Maryland Parkway on both sides of the roadway and down the middle.

That'll have a big difference on temperatures on that corridor.

-So if trees are part of the solution, why aren't more being planted?

Marci?

-Yeah, I think it's a matter of resources and more recent awareness about the impacts of climate change and how much more we're going to experience extreme heat and our need to act and to act quickly.

So a lot of mobilization, planning efforts at all of our agencies, and now sort of pivoting from planning into implementation, as Marco and and Andrew mentioned for their agencies, and mine, too.

-When you say "resources," are we talking about funding?

-We're talking about funding and capacity, capacity as well.

You know, human capacity, people to do this work and the funding to do it.

And so those are things that we're trying to figure out: How do we get those resources?

How do we take advantage of all the federal grant funding that's available, funding from nonprofit organizations, and put that in the projects and the places that need it most?

-Do you want to add anything?

-Yeah.

So not only are we focusing on the municipal urban forest, you know, the city's Tree City USA, and has been for a couple decades-- -Which means what?

-That we plant trees on Arbor Day, and we maintain our urban forestry commitment to plant-- to hit those long-term targets.

So not only are we doing that, we have an urban forester, and we already planted 4,000 trees at parks and with right-of-way street trees and those Complete Streets as we do those projects, but also on the regulatory side, for zoning, having trees being planted on private property and making sure that if there are trees that are lost due to age or disease or whatever the case may be, that they're planted with a Mojave native or adaptive tree that is compatible with it with the environment and is providing the benefits of the buildings that are immediately around it.

We need to make sure that we strengthen those, and that's how we get to those millions of trees that Dr. Lehmann was talking about.

-And those goals, are they all going to be focused on those areas where there is less tree canopy?

-I would certainly say that that's the starting point.

As was mentioned, you know, our master planned communities throughout Southern Nevada have had those development agreements or those zoning requirements in place for decades.

And that's why you see that ring around the city in the urban mapping, where the tree canopy is a lot-- is a lot greater than in Central Las Vegas and Downtown Las Vegas.

Focusing in the core itself is certainly the area where we want to start.

And then from there, just making sure that we're maintaining in those existing areas in the suburbs.

-Let's go back to you, Steffen.

You mentioned vegetation first.

What was number two?

-Materials and color.

-Okay.

-It's interrelated, and it's extremely important.

I would think it's equally important like vegetation.

We need to have roofs, for instance, that are not black, that are not supporting the urban heat island, but keep cool and reflect and use what's called the albedo effect.

So there is a reflective value, how much solar radiation is bounced back into the sky.

And the more albedo you have and, for instance, white buildings and light colored buildings are extremely good.

And we have to avoid things like black asphalt as much as possible.

I want to talk about how we do parking lots.

We see parking lots in Vegas that have not one tree.

I think we should change the building code here and also have maybe a building code change to say we don't want any black roof tiles.

There's a little bit of fashion, but they are, of course, devastating, and you have a huge cooling load in the building below.

And if you have black roof tiles, you have the worst situation.

So I think it could be a fair idea to change the building code.

The way we build parking lots, change that, and the way we maybe say, Let's not have any more black roof tiles.

-Marco, you're nodding.

Is that in the works?

Being discussed?

-Yeah.

So there are few places in Southern Nevada where you could arguably say that there's a white roof.

One example is City Hall, where we do have a white roof, but those are usually few and far between.

-And it's paint.

They're painted white?

-Yes.

So there are other techniques that can be done, you know, green roofs, having rooftop gardens, things like that.

We don't find a lot of those in Southern Nevada, but you know, in terms of our historic architecture that, you know, the houses and the structures that have been built, the Spanish style, you know, roofs, the shingles, the tile, that's just been how it's been done for decades and decades.

With some of those considerations for the urban heat island effect, you know, we'd have to start seeing a gradual increase over time, and that would only have to take place with changes in the zoning code.

The other thing is, you know, we've been a big believer in solar covered parking.

We have 40 facilities where we have solar covered parking, and that has provided some shade in those parking areas where, you know, the asphalt is otherwise hotter.

And you know, the parking spaces that are under those canopies are typically the ones that get filled up first because people value the shade.

And in addition to that, you have solar that's being generated for the facilities that they're at.

It's clean energy.

-The cool white roofs is something that the Desert Research Institute told an interim legislative committee about recently, and Senator Robin Titus had some thoughts on that, as well as on solar panels.

Let's take a listen to what she said, and then I'll have you respond.

(Senator Robin Titus) You mentioned that using the rooftops as white on top of these buildings, and that's been kind of a common sense thing to do for a long time.

And these big buildings and hot areas that you would, you would, you know, make them white to reflection.

And white cars don't heat up like the black cars.

Some of that is, again, common sense.

What I've been concerned about, though, that we have brought the solar industry into this, and now we're putting these solar panels on top of these roofs.

And we truly are making, in my mind, things hotter by putting these black panels on all these roofs and not having that white reflection.

-Marci, do you want to respond to that?

I mean, there is a difference between common sense and actually being common, the white rooftops.

-Yeah.

As Marco mentioned, we don't have a lot of white rooftops, and I think all of the local agencies are encouraging developers to do that and trying to educate folks on reducing their energy burden in the building, which will reduce their utility bills.

-If they have a white roof?

-Yeah.

Yeah, if they have a white roof.

So, you know, getting that education out there, explaining to folks how it benefits them.

But we, we do need to work on improving the amount of cool roofs that are going in, in Southern Nevada.

And I think the new building technology and the awareness of that is going to happen in new building.

But as Marco mentioned earlier, it then becomes almost like a retrofit situation for older buildings and making sure that we're putting programs and incentives in place to make sure that those changes can happen in those buildings as well.

-Andrew, this conversation looks a little bit different from the transportation perspective.

What is "heat mitigation" from the RTC perspective?

-Sure.

Just latching on to the white roofs, we have looked into white pavement for roadways, and it's a really tough environment to implement a reflective surface.

I think parking lots could be maybe a better example of someplace to roll that out and try it out.

And rooftops could be a good example as well.

But in terms of the roadway, like its impact on the overall urban heat island was kind of minimal.

And for someone walking, it was actually a little bit hotter.

Where the real benefit was of white pavement was at the actual surface level when you touch it.

This really borrows on research that the city of Phoenix and Arizona State University have done.

And LA as well.

They've done trials of pilots of white pavement.

Another additional thing about how tough it is to roll out white pavement on roadways is that the neighbors weren't really big fans, because there was a lot of vehicle track out, a lot of tire marks on the roadways.

What we want to do at the RTC is kind of support for the research in this area.

And if there's any pilots that the local agencies want to do in a parking lot, we're happy to participate in that.

But in terms of adapting to extreme heat at the RTC, we're really focused on our transit riders.

They are most exposed to this heat on a day-to-day basis.

And so we really have a robust program to deploy more bus stops, transit shelters, in these areas of extreme heat.

So about half of our bus stops right now in Southern Nevada have a shelter or an amenity there, and we're really focusing this next year on our new 300 shelters that we're going to roll out, where we're going to put them.

70% of those 300 shelters are going to go on the hottest parts of the valley.

-What would help you to implement more?

-Sure.

It always goes back to funding.

So just those 300 shelters is going to cost about $16 million.

-16 or 60?

-$16 million.

And so we can benefit from federal investment as well through the Bipartisan Infrastructure Law.

So about 80% of that 16 million will be funded by the federal government.

But another constraint that we have is just the width of the sidewalks.

So to put a shelter out there, we need to maintain ADA, Americans with Disabilities Act, clearance on that sidewalk.

We can't just go out and put a shelter on the sidewalk.

Oftentimes we need to go behind the sidewalk.

And so that's an easement.

That's coordinating with the private landowner.

In a lot of cases in Southern Nevada there's a wall behind the sidewalk.

And so we have a new technology.

It's called a slimline shelter, and we just started rolling these out.

And what a slimline shelter does is it allows us to put a shelter on these more narrow sidewalks to provide some shade and comfort to our waiting transit customers.

-All right.

You want to add something?

-Yeah.

So going back to what Andrew mentioned a couple of minutes ago about Complete Streets, and Maryland Parkway was one example where we're taking those sidewalks and making them wider as well as providing bike facilities, street trees, and amenities for transit users.

And that's where you're going to see a lot of the benefit is having a street that's redesigned and making it adaptable to all users.

And providing that shade is a key component of it.

And that's why we're making this a complete green street in both of those cases.

-Did you say "whiter" or "wider"?

-Wider.

-Wider, okay.

Because there is an issue with the white pavements and that some people report feeling hotter as a result of the sun reflecting off of it and then up onto them.

How effective are these methods that we are talking about?

-So vegetation has--we measured it, we have data on that--we found 20 degree Fahrenheit drop where you have a green roof or where you have a couple of trees.

It can be a significant change.

And coming back to the sidewalks, I think we like both wider and whiter.

-Okay.

You still think that should be implemented?

-Oh, yeah, absolutely.

And also, we need continuous shading.

Very important.

We need cooling corridors.

Otherwise, nobody's ever going to walk.

If you want to get people out of the car, you're going to have to make walking more pleasant, more safe, more comfortable.

People won't walk if there is no continuous shading.

How do you get continuous shading?

There are two ways.

Either you have a row of trees that have a continuous shade, not just here a little bit and there a little bit and in between you die.

But you have to have either a canopy or a continuous tree planting.

And canopy would be great also, let's say, I mean, we're not talking about the Strip, but the Strip would be the first cooling corridor, I would suggest, because we see tourists collapsing trying to go from one casino to the other.

And they underestimate a distance, and it's, you know, if you have 115 degrees, it's tough.

And they don't bring water along, and you see, actually, tourists collapsing on the way from one casino to the other.

So if we would have continuous canopies, you know, and a cooling corridor where people can walk safely.

-Do you want to add?

-I wanted to hearken back to what Dr. Titus was raising and also what Andrew raised.

I think what we're seeing is that you have to look at the full consequence of the action that you're taking.

And a lot of these heat mitigation strategies, what we're seeing is that there can be trade offs.

And so you have to think very specifically about the different treatments that will overall reduce the burden.

And so if you just slap white paint on pavement, you can get that reflective heating.

It has to be a combination of strategies to get the desired impact.

And it's the same thing with putting solar on the white roofs.

You have to look at that site in its entirety.

So if it's all black asphalt and, you know, concrete that's absorbing that heat, and you stick solar panels on a white roof, you're contributing mildly to that overall heat.

But if you put those combination of treatments--the whole building is white, you're using the cool pavement, you've got your landscaping--then you're just overall taking down the whole heat burden of the building.

So it's really a cross-cutting strategy approach.

And if we're just doing one action, we'd have to be mindful it could have a negative unintended consequence.

So we want to be thinking holistically about all of these opportunities.

-I think that's a fantastic point you make.

It's multiple solutions, not just one silver bullet.

And we have to have passive design principles, passive design strategies, put together.

Unintended consequences, as you mentioned, just comes one to mind.

Now we are tearing out the lawn because we said we're not allowed to have private lawn anymore.

And what do people do?

They put in the astroturf, the plastic.

It's a big sheet of plastic, which doesn't last longer than 10, 20 years in our UV light, extreme heat, so the plastic decomposes.

We have a microplastic problem in the soil.

It's just leading to another issue, unintended.

People want to see green, but they think by putting in a big sheet of plastic, it's going to be nice.

Have you ever walked barefoot over astroturf in summer?

It is actually supporting the urban heat island, it's a plastic issue, and so on.

So all those unintended consequences you mentioned are very important.

-Thank you all for joining us.

And thank you for watching.

For any of the resources discussed, go to vegaspbs.org/nevadaweek.

And I'll see you next week on Nevada Week.

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