Effectiveness of trees in reducing temperature, outdoor heat exposure in Vegas

Trees, Heat, and Desert Cities

• Broad agreement that vegetation dramatically improves outdoor comfort compared to bare concrete, with multiple anecdotes from deserts and hot regions (Las Vegas, SoCal, India, Spain).
• Some argue “don’t build cities in deserts” while others note humans have long lived in arid regions; the real issue is how we design and supply them.

Water Use and Scarcity

• Strong pushback on the idea that urban trees are the main water problem: in much of the American West, ~70–80% of water goes to agriculture, with municipal use a small share.
• For Southern Nevada specifically, indoor use is heavily reclaimed; Las Vegas has reduced per‑capita water use substantially while growing.
• Counterpoint: water lost to evapotranspiration from trees cannot be reclaimed, which conflicts with strict local conservation policies.
• Some see water scarcity as largely political/technological (desalination, pipelines, nuclear/solar energy); others stress aquifers and rivers are already overdrawn.

How Trees Cool

• Discussion clarifies that in this study and in Vegas:
  • Main benefit is shade and reduced radiant load (reported up to ~16°C lower mean radiant temperature under trees).
  • Evaporative cooling adds only a small extra effect (~0.5°C) but costs much more water.
• Explanations offered: trees intercept solar radiation high above ground, have large surface area with low thermal mass, and convert a small portion of light to chemical energy.
• Debate whether trees are more “effective” than swamp coolers; physically water is water, but trees uniquely provide shade and vertical heat dissipation.

Alternative Cooling and Shade Strategies

• Several argue that if the goal is shade (not evaporation), simpler structures may be better: fabric/metal canopies, solar carports, brise‑soleil, high‑albedo surfaces, underground spaces.
• References to traditional passive cooling in hot regions: windcatchers, salsabils, thick thermal-mass walls, narrow shaded streets.
• Solar panels are highlighted as especially well‑suited for the Nevada desert: they provide shade and power and can be engineered for improved radiative cooling.

Tree Species and Local Ecology

• Concern that the study’s use of Bur Oak (non‑native, moderately water‑intensive) misrepresents what’s appropriate for the Mojave.
• Others suggest using native or drought‑adapted species (cottonwoods, mesquite, juniper, Mediterranean-type trees, succulents) to balance shade with low water demand.
• Skepticism toward large-scale “greening” with non‑natives in expanding desert conditions; better to align with climate rather than fight it.

Urban Planning, Livability, and Tradeoffs

• Trees improve walkability and “street life,” but require budget, maintenance, and space that can conflict with parking and traffic lanes.
• Some argue desert cities should stop trying to look like temperate suburbs and instead embrace climate-appropriate architecture and expectations.
• Equity angle: dense, treeless “concrete hellscapes” in hot countries and rebuilding cities often sacrifice shade first when budgets are tight.

Meta: Access Barriers

• Multiple comments criticize the site’s aggressive, confusing captchas and redirect behavior, which significantly hinder reading the paper and archiving it.