Effectiveness of trees in reducing temperature, outdoor heat exposure in Vegas
Of course it's Vegas, I wouldn't be surprised if we decided to make the downtown completely indoors so we could just run AC in the streets too. It's not exactly the city of practicality.
the downtown completely indoors so we could just run AC in the streets too.
So ... a shopping mall? Many cities do this already, linking various public indoor spaces by walkways/tunnels. Also those cities where the air outside is too cold. A few canadian universities link buildings with tunnels so students can avoid going outside.
on top of the air cooling effects of evaporation
I think you meant to say *on top of shade* because blocking the sun is the main effect here (the geometry makes more sense too!)
Less confusing phrase from abstract which implies that the 0.5deg evaporative cooling is almost a rounding error:
during the day, trees provide significant shade by intercepting solar radiation, reducing mean radiant temperature (up to 16 °C) during the day, trees provide significant shade by intercepting solar radiation, reducing mean radiant temperature (up to 16 °C)
The main benefit over other solutions is that properly selected trees require very little upkeep from humans, unlike anything mechanical or requiring movement. Though I imagine that is less the case in Vegas.
Only ambient sunlight needed here, but they'd have to make the panels horizontal (indeed, curtained at night like you say) somehow:
https://www.thebrighterside.news/post/mits-high-tech-hydroge...
Edit I guess the low-maintenance option might be some kind of giant variegated Madagascan succulent
Right where I am sitting now I have an LED strip above my desk and when I have my shirt off (right now) I can very definitely feel the radiant energy when it is on, so if it is really hot I either turn it off or switch it to green because the eye is most sensitive to green light. In fact, as I'm writing this, I just set the backlight on the 55-inch TV I use as a computer monitor down so I'd feel more comfortable.
https://www.thebrighterside.news/post/mits-high-tech-hydroge...
Mostly the benefit is instead of having the concrete under you absorb and emit the sun, the leaves above you do.
This dramatically reduces the heat we feel at human height.
the effect (16deg Celsius)
Did I read that right? 16°C seems like an enormous effect.
Seems like trees would be a small investment to effectively get "outdoor AC-ish"?
EDIT: for those of us who are more comfortable with Freedom Units, that's like going from 104°F to 75°F!
Wrt. water consumption - Mediterranean species like say olive trees are kind of optimized for low water consumption, by for example having leaves covered with wax-like stuff decreasing evaporation.
they just need to figure a way to reorient their panels to provide shade?
[0] only sunlight needed
https://www.thebrighterside.news/post/mits-high-tech-hydroge...
Re: olives, hopefully the terpenes can also help cloud formation
Trees excel at harvesting water.
Specifically, some kind of giant succulent would be best for arid climes
This sequestration can be long term if things go well or it can be short term if plants die in large numbers (because of climate change, diseases...).
The funny thing is, if you build a wall or canopy to avoid the water consumption plus literally waiting a decade for a tree to get tall.. now you're probably in violation of your HOA height restrictions, etc. Desert cities need to basically drop the idea of conforming to the typical expectations of visitors and newcomers by trying to add greenery. It's better to add shade, dig underground, build wind-catchers[1], salsabils[2]. There's tons of basic things like making sure roof surfaces are more reflective, and more strategic architectural things[3] that can be done to improve things and the techniques have been used forever
[1] https://en.wikipedia.org/wiki/Windcatcher [2] https://en.wikipedia.org/wiki/Salsabil_(fountain) [3] https://en.wikipedia.org/wiki/Passive_cooling
https://solar.lowtechmagazine.com/2025/06/dressing-and-undre...
The limited effect is that cities are dense and can't be made as forest so trees can't do nothing for buildings taller them them.
Increasing *evaporative* cooling by 0.5deg requires 3x more water, but shade alone is the *main* mechanism,it doesn't require water.
during the day, trees provide significant shade by intercepting solar radiation, reducing mean radiant temperature (up to 16 °C)
https://www.knpr.org/show/knprs-state-of-nevada/2024-08-29/w...
For instance where I live east of the Cascades, in the dry part of Oregon, only like 10% of the water used goes to the cities.
https://www.centraloregonlandwatch.org/update/2021/5/5/droug...
Street trees are hugely beneficial and if you want to cut something (ha ha), you want to look at things like lawns or golf courses.
In 2014, Southern Nevada’s gross water demand was about 205 gallons per capita per day (GPCD). In the region, single- and multi-family households account for 60 percent of water consumption—70 percent of which is used for landscaping.
I found this quote in this 2016 PDF from the EPA:
https://www.epa.gov/sites/default/files/2017-02/documents/ws...
However, large scale commercial agriculture in desert areas without significant ground water - that's a new thing, and it's a problem.
(or were victims of non-anthropogenic desertification)
*note: the same process going on currently also via multiple means :(
While human activities undoubtedly contributed to desertification, the Levant is geographically and climactically a desert. The amount of surface water that is available may be directly influenced by human behavior, but I do not think that human behavior changed the fundamentals of the landscape.
Am I wrong?
We identified why north Africa greened approximately every 21,000 years over the past eight million years. It was caused by changes in the Earth’s orbital precession - the slight wobbling of the planet while rotating. This moves the Northern Hemisphere closer to the sun during the summer months.
*What Really Turned the Sahara Desert From a Green Oasis Into a Wasteland?* - 10,000 years ago, this iconic desert was unrecognizable. A new hypothesis suggests that humans may have tipped the balance
While I personally veer toward the more recent slight orbital variation cause, neither account factors much in the current AGW debate .. cyclic changes in local regions of the planet are a distinct issue from a steady rise in global atmospheric insulation properties.
On the other hand for the Fertile Crescent: the overuse of irrigation and water steering with shorter term agricultural goals with only direct affects in mind. The area was largely marshlands in the past.
And also mismanagement of forests lead to desertification of formerly fertile areas on the timescale before the current large scale climate change era began. This was before humanity could have as big possible part in the forming of climate as currently.
Desalination that runs off of Solar panels makes it pretty viable for places like Dubai to exist. The cheap solar energy from the Desert, makes it attractive for future data centers to be placed there. Also, Ancient Egypt had slaves. A lot of the modern middle eastern states rely on cheap labour from India and Afghanistan. And Oil money ...
(also, I don't think the Central Valley is actually a desert?)
https://www.cleanwaterteam.com/about-us/who-we-are
[Las Vegas] used 38 billion gallons less water in 2024 than in 2002, despite a population increase of approximately 829,000 residents during that time. This represents a 55 percent decline in the community’s per capita water use since 2002.
OK, let's go full mad world: a vast web of PV for power. Is there a handy massive water resource deep underground? If not then moisture in the air will need redeploying. Tall towers and probably gobs of power are indicated for that.
If people were really serious about living in deserts in a sustainable way, they can't expect to have decorative greenery or classic architecture. A society as advanced as ours should be able to make compromises that allow modern comforts while adapting so well to their environment that the cities would look almost alien.
The architecture has existed for centuries, maybe even millenia. Some of us already live that way.
The irony is that the key thing - large thermal mass - has now become the province of only those with lots of money, or those with no money. Everyone in the middle is stuck with silly construction options for a desert climate.
Trees were the first thing planted. Fast growing trees, placed to cast shade on the house.
After a few years, those dirt lots transformed into some very nice properties where sitting outside in the shade with the desert zephyrs rustling the leaves provide a very nice, idyllic place for conservation or reading.
Since the point of the trees has been discovered to be just shade and not evaporative cooling, they just need to figure a way to reorient their panels?
[0] only sunlight needed
https://www.thebrighterside.news/post/mits-high-tech-hydroge...
I agree growing things in the desert may be inefficient, but speaking for the CO river, that problem is in California and Arizona.
https://www.snwa.com/water-resources/where-water-comes-from/...
Edit: And cooling only works inside buildings or cars. Part of a comfortable city is being able to go outside and have a social life outside of a casino.
We pump oil via pipelines vast distances, we can do the same with water.
We have virtually unlimited energy locked in Uranium which could power desalination plants, or heck you could power them with solar.
There’s plenty of water for the whole planet. There’s also plenty of clean energy (see nuclear and solar point earlier). But tapping these resources requires a functional government or at least a bureaucracy willing to allow companies to build.
For Las Vegas, Cottonwoods are native and grow pretty quickly. Like many poplars they were used to grow shelterbelts.
If the US' alfalfa exports to Saudi Arabia went down by 10%, we would never have a municipal water shortage in the American West in the next century.
Very few municipalities are willing to deny new residents, either. It wouldn't be anywhere on my list of viable places to live, but population growth in the Las Vegas metro area has been consistently large since 1910 until recently (only 10% growth from 2010 to 2020). The municipalities should likely invest in livability and comfort where possible.
This time of year when you opened the gate that separated the treed interior from the parking lot you felt like the air conditioning had been turned on. We have very fond memories of the place. Its only disadvantage for me was that spring caused my allergies to go crazy.
Totally worth it.
I see some trees but it doesn't seem like a dense concentration.
Fuck off.
Then that vanished and another even more vapid effort appeared.
Fuck off.
If you need to piss around with this sort of nonsense, you probably shouldn't be entrusted with a website.
looks like the archivers have trouble with it too; reminds me of the behavior of a virus with all the redirects lol
edit: for those with custom filterlists via ubo:
- ||iop.org
There's also a direct PDF link https://iopscience.iop.org/article/10.1088/2752-5295/ade17d/... that also prompts for captcha (unless you arrive there via the web version)
Looping redirects on archive.XX urls often traces back to the use of Cloudflare DNS resolver .. the archive folk have some beef with Cloudflare over (?) handling privacy (?) and loop redirects on connections that arrive via that path.
It's a new captcha type for myself also. Interesting as it requires spatial reasoning and a bridge of understanding between text request and objects in images - although it falls to the usual farm of human captcha solvers.
This seems to be the offending product being used, although the captchas themselves are standard hCaptcha.
The selected tree species is Bur Oak, given that it is included in the SNWA Regional Plant (SNWA 2021) list, it is marked as a street tree in the list...
Who the hell is planting oaks in Vegas? Oaks are non native and moderately water intensive trees. If this study is based on oaks, it calls into question the validity of the data since this is a tree that absolutely does not belong in the Mojave desert.
It's actually comfortable to be outside there. Even in the summer it's almost completely shaded. I was kind of surprised how extreme it is. I know trees make it harder to work and if you're hiring people they probably can't tolerate it but since I'm doing everything myself I don't have to clear everything and wait for it to grow back.
"Angeles" has 3, and is already too much. So they say L.A. (2 syllables).
It's the same reason you call New York in full (not N.Y.), as it's already 2 syllables.
What happens if you import northern US trees, the ones that produce a lot of shade, into southern states? Has this been tried?
It is also why there is very little shade in, say, Florida. Only occasional parts of the Martin Grade “scenic” highway look like a regular scene in the north.
But it is more complicated than that, of course. It's not just "how hot does it get", but also how much water is available, how windy it is, how cold it gets, and a million other environmental factors. That's why there is such a wide variety among the plants on earth.
(and yes, it has been tried. Check out the youtube channel "crime pays but botany doesn't")
They should be more proud of their findings. Why insult it out of the gate?
The sky is rarely cloudy and solar just blasts all day every day here.
I covered my backyard in Vegas with ground panels and now I charge my EV off of a 100% off grid solar system. The sun provides enough energy in my small yard for 2-3x my driving needs.
https://web.stanford.edu/group/fan/publication/Li_ACSPhotoni...
"[...] we design a photonic cooler made of one- dimensional photonic films that can strongly radiate heat through its thermal emission while also significantly reflecting the solar spectrum in the sub-band-gap and ultraviolet regimes. We show that applying this photonic cooler to a solar panel can lower the cell temperature by over 5.7 °C."
Air temperature is already high (e.g. 36C at my location just now), and radiant heat from sun and concrete can make the felt temperature more like 60C.
It's sad that new real-estate layouts continue to be approved, which will only be good for this type of dense concrete hell.
Plant trees, not ACs...
North America's greed for energy resources is just bonkers from an outside perspecive.
The abstract does lay this out pretty well.
Las Vegas is embracing a simple climate solution: More trees (npr.org) 21 days ago | 143 comments https://news.ycombinator.com/item?id=44231151
Nights in Las Vegas Are Becoming Dangerously Hot (nytimes.com) 10 months ago | 1 comment https://news.ycombinator.com/item?id=41223831