Staying Cool in a Hot World
Shade matters, more than ever in a warming world
A recent Twitter interaction led me down the rabbit hole of how the use of air conditioning (aka cooling) affects climate change. A World Economic Forum article points toward cooling consuming 20% of global electricity demand. That’s a staggering amount that will only climb as parts of the world become too hot to inhabit without cooling.
No doubt generating electricity will create more greenhouse gas emissions unless it comes from greener sources like wind and solar, but we’re going to need more electricity as the world heats up.
Shade in the brutal heat
I remember working outside in the brutal Albuquerque heat. It was the summer of 1995 and I was inspecting the construction of the new Paseo Del Norte bridge. The Contractor had his work crews start at 6 AM and then knock off at 2:30 PM.
Why? Because the brutal heat started around that time. Between 2:30 PM and 5 PM, doing any kind of physical labor outside became unbearably hot.
I would listen to the radio for the weather forecast and would head to any bit of shade I could find for my lunch break. While the climate in the high desert was a “dry heat,” it was nevertheless dangerous. You didn’t know you were sweating out pints of water and needed to drink a lot of water just to stay hydrated.
I remember drinking large containers of water every day just standing and inspecting the construction, then getting into my non-air-conditioned work truck and driving back to the office. I look fondly at those times but I do remember being very uncomfortable and missing my air-conditioned office.
My apartment was a bit different, we had swamp coolers. These were units that used evaporation to cool off your living dwelling. They would spray water on absorbing pads and then pass hot air through them. The evaporation of the water would cool the air before it got pumped into my apartment.
At the time I didn’t think of the ramifications of wasting water in the desert, I just wanted to get cool. I did try to conserve electricity and raise the temperature to 75F. Albuquerque was hot in the summer but it felt bearable in the shade and with a bit of cooling.
Heat islands
I remember the summer evenings in Albuquerque, they were warm and clear. Perfect summer evenings with a bit of a breeze off the mountains and mesa. Little did I know that was all the heat radiating back into space from the pavement and building structures.
What I thought was a perfect summer evening was just the after-effect of a heat island. Cities and other urban areas are prone to something called heat islands, or urban heat islands (UHI). All this means that built-up urban environments tend to be hotter than any surrounding rural areas, areas less developed.
The tons of asphalt, concrete, and glass in our cities tend to reflect and absorb the sun’s radiation and the air temperature around them rises. We tend to notice this temperature differential in the evenings more than during the day.
I never took much notice of UHI’s until a few years ago, until things started getting too hot and I saw the effects with my own two eyes.
The temperature game
I live in a fairly wooded area of New Jersey. My partner and I decided to move deeper into the woods to give our kids access to a swimming lake and other fun things. I remember driving with them back home from somewhere on a hot summer day. The temperature gauge read 100F as we were driving through a very built-up urban area.
As soon as we entered the perimeter of where the forest began I noticed the temperature drop to 98F. I thought that was interesting and saw the temperature drop another tick lower the deeper we penetrated the forest perimeter.
I called out the kids to play a new game, I asked them to take bets on what temperature it would be when getting to our house, now deep in the woods and under a lot of tree cover. They made their guesses and I watched the temperature drop even more the closer we got to our house.
By the time we got to our house the temperature gauge stood at 89F. A whopping 11-degree reduction from an urban sprawl area to wooded rural suburbia. Of course, this temperature reduction varies throughout the year based on the cover of the trees but 11 degrees is an 11% reduction, and that translates to less cooling and less electricity usage.
The trees I’m surrounded by cool me where I live. They’re the first line of defense against a warming world if we were forced to live in it. They might not all make it but we need to start protecting our trees and shade as if our life depends on it, because it very well might.
From red to green
The majority of people live in cities and our urban planning over the last century has left much to be desired for. We planned to remove water and sewage, for public transportation, and cars. Did we plan for trees and nature? Yes, but they were an afterthought a lot of times. People didn’t want to look at concrete boxes all the time, they wanted some visual contrast, and planting trees as part of landscaping made sense.
Cities and towns set up shade tree commissions to plant more trees but this always happened after something was built. Developers would rather put grass in as part of their soil erosion and sediment control practices because it was easy and looked good.
Yet something more sinister might’ve been at play in determining just how many trees were planted in different areas. This is where America’s racist past comes into play with redlining, a discriminatory practice in the early part of the 20th Century that affects millions of people of color to this day.
Fighting redlining is just one part of a city’s planning process. There are many moving parts in urban planning like public transportation and fighting sprawl but perhaps we need to take a closer look at how we can use the environment to build better heat and climate resilience.
My first thought, as a civil engineer, is to embark on a massive shade trees initiative for each city. Many cities already have a Shade Tree Commission and are designated Tree City USA members, but more needs to be done.
We need to rethink how to build new complementary and thriving ecosystems in our urban areas, not just planting trees. The ability to provide shade and natural cooling is just as important as providing ecosystems for birds, insects, and wild animals. At first glance, you might not believe that urban areas can support a myriad of wildlife, but they can and do.
My neighbor learned his beekeeping skills from an old beekeeper in Newark, NJ. This man kept dozens of hives in the city and these bees would pollinate many wildflowers and weeds in vacant lots. Yes, the urban blight of Newark, NJ became a habitat for the bees and honey for us. I’m sure that these wildflowers that eventually went to seed became food for songbirds.
That’s the neat and insidious thing about nature, she abhors a vacuum. Nature will burn us out of our cities if we don’t start greening it. Now, more than ever, the quality and amount of shade will determine how survivable your city will be.
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