Cities are vulnerable to heatwaves. But green spaces can help more than we thought
Cities are vulnerable to heatwaves. But green spaces can help more than we thought
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Breaking news: it's cooler in the woods during the summer than outside the woods.
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That's certainly the case here in São Paulo: the city has a pathetic low number of green spaces but several districts are full of tree lined streets. São Paulo was notorious for its milder summers (hottest month had 18oC min and 27oC max average). Now, the averages are good 3oC above and people will certainly seek for shades more often. |
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Now be nice, or else I'll start posting photos of the Nashville skyline and you'll end up blinded or driven insane at the very sight. Don't think I won't do it either. |
We planted a black oak sapling in the parkway in front of our building last summer.
Gonna take a while (couple decades) before it's casting any meaningful shade, but hey, you gotta start somewhere. And once they get going, these black oaks can really go the distance. My kids' school grounds a block south of us has three GIGANTIC black oaks from the before times. They brought in a tree dude who estimated that they're all 200-250 years old!! There wasn't even a Chicago yet when they first sprouted outta their acorns. I hope the black oak we planted can go 200+ years. |
Of course trees provide shade and cool the urban environment, but I struggle a bit with desires to have extensive tree cover in climates that don't naturally support forests. I see this in the Los Angeles area all the time, where neighborhood groups and tree enthusiasts are always advocating for more and more trees to be planted in public right of ways, trees retained on private property, etc. Historically, Los Angeles was not a tree covered place (in the mountains and along natural waterways, yes, otherwise, no), and we don't get the year round water required to keep trees healthy throughout the year. Yet that doesn't stop people from wanting their neighborhoods to look like Atlanta.
You move to a place because it's warm and sunny 9 months a year, but you also want a lush, shady, forested environment? For some reason, this just really bothers me. Don't move to a semi-arid climate and expect to live in a shady forest. In drier climates, I think cities should try to promote shade structures, awnings, colonnades, etc. rather than create artificial forests that require irrigation. |
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In any case, the city itself changes way more the natural environment than the trees that come along as consequence. |
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I'll show you, cause studies by urban planners are spectacular in that matter. The guy with glasses in that report from July of 2022 is a teacher in urban planning and an activist to defend trees in Central Paris. 0:45 Right there, you're standing on place de l'Opéra, a square usually full of tourists. But there was none when they shot that report, because we were on a hellish heatwave. That square is only limestone of buildings around and asphalt on the ground. Not a single tree on the square. So it's what they call "îlot de chaleur" (a heat spot) in case of heatwave. The activist calls it a hostile environment, while it's a prime location at the center of the CBD in the inner city. Temperature at ground level would be greater than in the Sahara desert when Paris is hit by some heatwave. 1:55 55.9°C, or 132.6°F on that very spot in front of the old opera house. It goes up to 57 or 58°C (134 to 136°F) Now look at that... 2:40 The guy just only walked over 100m (100 yards) to boulevard des Capucines. There are trees on the sidewalk right there, then the temperature drops to 23.7°C (74.7°F). :sly: It is so unreal that I still wonder whether his gear would be reliable. I mean the difference over 100m is so insane that it seems fake. Still, I don't think the guy would lie. That would be too bad for his reputation as a teacher in a college. 4:15 This woman is a researcher who works on very local weather conditions. She says they were working on a French-Indian satellite to spot "îlots de chaleur" more accurately, to the scale of a single urban block, like it couldn't get any more accurate. This is obviously highly strategic in this city today. |
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https://www.themayor.eu/web/files/ar...l-awnings.jpeg https://www.themayor.eu/en/a/view/se...n-summer-10149 Quote:
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Trees make more sense in places like Los Angeles than green grass lawns. The region would be better off if people stopped watering lawns and shifted to watering shade trees instead.
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Tree planting to moderate the effects of heat and to improve air quality has been standard practice in many cities for quite a long time now. Some have gone further.
Toronto was the first North American city to require and govern the construction of green roofs on new developments. The Green Roof Bylaw sets out a graduated green roof requirement for new buildings that are greater than 2,000 m² in gross floor area. These measures help make the city more comfortable in summer but can improve food self sufficiency through urban farming. A Roof Top farm was installed atop the Toronto-Dominion Centre pavilion in 2012 https://cloudfront-us-east-1.images....JH6A2W2V5ZUY7M https://www.theglobeandmail.com/news...rticle4276138/ |
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My yard has numerous trees, including palms, pines, and fruit trees. Many of them are over 50 ft. tall, as most were planted around 1965. We don't water any of them. Ever. They have deep roots that extract all the water they need and that also stabilize the hillside so that there's no slippage when we get heavy rains in winter and during summer thunderstorms.
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Reminds me of a meme I saw this morning:
https://live.staticflickr.com/65535/...430c0268_z.jpg Regarding Los Angeles and SoCal, people seem to think that there's no such things as aquifers and underground streams/rivers. Once tree roots hit a water table, you don't even really need to water it. There are also native trees, of which the indigenous people knew/know how to cultivate. They were a food source after all, and if anyone knows about Los Angeles history, they would know about the towering 400 year-old sycamore tree that the native Tongva used to revere and hold meetings at, a tree that eventually met its demise in the late 1800s. The Spanish colonizers referred to the tree as El Aliso, from which the present-day Aliso Street in downtown LA gets its name. Here are few samples of native SoCal trees, from California Native Trees. Arctostaphylos “Sentinel” showing off its winter flowers. https://live.staticflickr.com/65535/...3ca7b0e0_b.jpg Sycamore. https://live.staticflickr.com/65535/...91e29408_b.jpg Quercus agrifolia. https://live.staticflickr.com/65535/...3eedb44e_b.jpg And here's the story of El Aliso. |
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