July 1, 2021

Heat Waves & Climate Change: what is a “Wet Bulb Temperature?”

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Much of Western Canada and the United States have been going through an early summer heat wave.

Records are breaking left and right in British Columbia, Alberta, and south, in the PNW area of the U.S. including the cities of Portland and Seattle.

People are miserable. People are dying.

As a person in the #noairconditioning club, I’ve been doing my best to stay cool with fans, wet dishcloths around my neck, and managing my windows and coverings during the days and nights. Also, I’ve been making sure my pets are as comfortable as possible. (Frozen peanut butter treats for the dog are a hit!)

That’s about all I can do in the short term, and thankfully, today, it seems, will be the last day above 35 degrees Celsius (95 for Americans). In the long term, I know that there are a ton of things I can continue to do to support Mama Earth.

Recently, though, as I was laying on the floor, sweating my face off (despite the two fans pointed directly at me), and watching TikTok, I came across a term I hadn’t heard before: “wet bulb temperature.”

I’ll let the TikTok do the talking for me, since it’s explained so well here:


@hankgreen1Yesterday was wet bulb 77 in Portland, hot enough that people with health problems could die without A/C. ##learnontiktok ##tiktokpartner♬ original sound – Hank Green

A deeper explanation from Wikipedia:

“The wet-bulb temperature (WBT) is the temperature read by a thermometer covered in water-soaked cloth (wet-bulb thermometer) over which air is passed.[1] At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature); at lower humidity the wet-bulb temperature is lower than dry-bulb temperature because of evaporative cooling.

The wet-bulb temperature is defined as the temperature of a parcel of air cooled to saturation (100% relative humidity) by the evaporation of water into it, with the latent heat supplied by the parcel. A wet-bulb thermometer indicates a temperature close to the true (thermodynamic) wet-bulb temperature. The wet-bulb temperature is the lowest temperature that can be reached under current ambient conditions by the evaporation of water only.

Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of 32 °C (90 °F), equivalent to a heat index of 55 °C (130 °F). The theoretical limit to human survival for more than a few hours in the shade, even with unlimited water, is 35 °C (95 °F) – theoretically equivalent to a heat index of 70 °C (160 °F), though the heat index does not go that high.”

I mentioned this to my son when we were commiserating about the heat, and he said, yeah, this is going to be what my life is like, more and more: getting through extreme weather. It’s part of why, at only 21, he’s already made the choice not to have kids.

But he’s lucky because he’s a white, educated male living in Canada. He probably won’t really have to worry (for a while yet, anyway) about the “wet bulb temperature,” even if he opts not to have air conditioning when he moves out to live on his own.

Climate change isn’t totally out of our hands. Although we’re nearing (or have crossed) that no-return threshold, we still have a chance to avoid even worse outcomes. For us relatively rich people in Canada and the U.S., it’s a mild inconvenience. I acknowledge some, like the houseless, have it far worse—but even they have cooling shelters set up (at least here in my city) to seek relief. For those outside of wealthy nations who are going through severe drought, flooding, famine—it’s their daily life, and we’re letting their suffering happen and making it worse.

Eventually, though? It’ll get us too.

Here are a few things to do if you genuinely want to be a part of the solution:

(And why wouldn’t you want to?!)

1. If you’re not willing or able to go completely vegan, just eat less meat. Easy. One or two days, at least. This small change, done collectively, would make a huge impact. We have a whole section on Elephant dedicated to food and recipes here. (A few notable authors to follow on Elephant are Hilda Carroll and Janice Dolk.) And here’s one of our most popular recipes, perfect for a heat wave.

2. Act like you’re dirt poor, and fix your sh*t. Instead of throwing something away, learn how to fix it or upcycle it. There’s a reason why our grandmas have closets full of cool clothes that are coming back into fashion and mixing bowls that never quit. Thanks to the Great Depression, they had no choice but to make do with what they had, and they’ve carried those values forward. This throw-away culture we’re in is maddening to me.

3. End your food waste. Read this article for more advice. The gist, though, is that it’s totally possible to cut down your grocery bill and stop throwing away perfectly good food, which lends to lots of benefit down the line: fewer chemicals used to produce the food (and fewer animals, if you’re a meat-eater), less transportation to bring that food to you, less plastic packaging…and the list goes on.

I’ll leave off with a few more of my favorite climate change TikToks:


@willow.skyDear, 2045. by me #globalwarming #fyp #awareness #singing #climatechange #stopclimatechange #song #foryou♬ Dear 2045 – willow sky

@bonjourbeckyhot girl summers here we come ? #climatechange #ecoanxiety #realization♬ original sound – JazzyFizzle

@samuel_j22#planet #climatechange #change #life #fyp #wild♬ Interstellar – Main Theme -Trailer Version Extended (2014) – Meridian Studio Ensemble

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