The heat

Lisa McNeilly.

Scottsdale has a way to go in reducing urban heat, according to some residents.

Of 56 responses to a survey on the city’s urban heat plan, 88% say it is “very important” for the city to take action to reduce urban heat. However, only 48% say Scottsdale is doing an “average” job or better in creating cool and comfortable spaces for pedestrians to go.

That was the message Scottsdale Sustainability Director Lisa McNeilly had for City Council during its meeting Sept. 13.

McNeilly gave a recap of the city’s heat mitigation plan, which is still being formalized.

She stated radiant heat (the heat you feel around you) drops by 55° F under a mature, fully-leafed tree. That number is 30° F for desert adapted trees and 50° F under a bus stop terminal with full, wide shade structures.

“It’s not necessarily surprising that mature trees are cooler, that standing under a tree is cooler, even standing under a mature, desert-adapted tree is cooler, or being under a bus stop or other structure shade is cooler,” she said.

“What really surprised me was how much cooler – 55 degrees is a lot. What this study gives us is that it took something that we knew and helped us quantify it, which is going to be helping us as we develop this heat mitigation plan.”

She repeated some information already shared with the council, such as: on average, Scottsdale’s growth areas (the Air Park, Old Town and south Scottsdale) land surface temperatures are 6° F to 7° F higher than the rest of the city and census block groups with higher average incomes had lower temperatures. Land surface temperatures decreased about more than 1° F for each $10,000 increase in mean per capita per home.

The reason is there’s less asphalt and more trees in more affluent communities.

The plan has three recommendations:

Increase tree canopy, particularly along frequently traveled pedestrian walkways and along the south and west facades of buildings.

Reduce the land area of exposed dark asphalt, dark roofs and other hot surfaces.

Improve and increase pedestrian shade amenities through building integrated and free standing shade structures.

She opened her presentation with a statement of how bad the problem is.

There have been 153 confirmed heat related deaths in Maricopa County this year, she said.

“We’re having fewer heat warning days than we did in 2020 but our night time low for June and July was 84.3° F, it averaged that, which is warmer than any year since 1950,” McNeilly said. “We know temperatures in Arizona have already gone up 2.5 percent since 1900.”

The point is, Scottsdale is getting hotter, and that has real consequences.

“The challenge we always have and I always include in my newsletters is what’s causing the heat,” Councilwoman Solange Whitehead said. “It’s hot and getting hotter so what’s causing heat? That’s where I think there’s a big gap in knowledge.”

“What else causes heat? Internal combustion engines, cars,” Whitehead continued. “That’s a big source of heat in our cities. Concrete … the type of materials we use to build buildings reduces urban heat and reduces utility bills. I think people say, ‘Oh it’s hot, lets plant a tree,” but I think we really have to educate people as to what is causing the heat. That’s where we need to make some changes.”

Neither Barry Graham nor Pamela Carter, the two candidates facing off in the Nov. 8 general election for the last open seat on council, were present at the meeting.

However, Graham told the Progress, “Addressing heat-island effects, which are partially due to excessive development, is critical for the health of our residents – especially senior citizens with compromised immune systems. There are common-sense solutions to reduce uncomfortable and unhealthy heat retention, like adding trees and shade structures, redesigning heat-trapping surfaces, and discouraging unused emissions.”

Attempts to reach Carter for comment were unsuccessful.

McNeilly also gave the council an update on the creation of the city’s sustainability plan.

“I wanted to start not with the problem, but with our success,” McNeilly said. “This may be the city’s first sustainability plan, but I am not the first sustainability officer here. There’s been a lot of work. It’s a special place that has consistently championed environmental stewardship while maintaining a high quality of life for our residents, our visitors, our businesses.”

McNeilly and her team conducted four work studies to gather public input this year.

She has compiled the information into five pathways. They are:

• Low emissions and climate action – reduces greenhouse gas and other environmentally harmful air emissions.

• Nature-based – protects and enhances city and natural environment by conserving resources, balancing land use and open space.

• Equitable community – builds just, livable and thriving communities reflecting the character of Scottsdale.

• Resiliency – anticipates and responds to shocks and stressors, preparing for new risks and impacts.

• Circular systems – supports models of production and consumption that support reducing, recycling, repairing and re-purposing products and materials.

• These are fleshed out with topics and specific recommendations on how to achieve goals, such as replacing the city fleet of vehicles and buses with electric vehicles.

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