This article was first published inÂ
I had bought the tickets in advance, so it was a coincidence the weather was sweltering hot that July day in 1992 when we headed to the theatre for a performance of the musical 110 in the Shade. The show, based on Richard Nash’s 1954 play The Rainmaker, is set in July 1936 and opens with a rousing rendition of Another Hot Day as the townsfolk eye the sky for a sign of rain amid a blistering heat wave that has descended on the Southwest. A charismatic con man comes to town promising to make rain for a fee and strikes up a relationship with Lizzie, a local spinster who is also involved with the town’s sheriff. The theatre was comfortably air-conditioned, but heat figuratively radiated from the stage with the set featuring the constant presence of a giant sun in the background.
This memory was rekindled as a result of my delving into the history of heat waves, stimulated in turn by questions being raised about the consequences of global warming. It turns out the . Temperatures soared to all-time highs, actually hitting  in the southern United States. New York City sweltered in 106-degree temperatures and record highs were noted as far north as Ontario and Manitoba. Dust storms were prevalent and a grasshopper infestation that had affected the Midwest now saw the creatures literally fall from the sky, broiled and lifeless. Hospitals and morgues were overrun with an estimated 5,000 Americans and 1,100 Canadians dying as a result of the heat.
Heat can, indeed, be deadly, but our bodies have evolved to combat it in two ways. The evaporation of sweat requires heat and that heat is taken from the skin, cooling it. At the same time, there is dilation of blood vessels to increase blood flow for improved transfer of heat from muscles to the skin. This enhanced blood flow requires the heart to pump harder and faster, increasing its demand for oxygen. If that demand is not met, which is more likely if there is already some underlying cardiovascular disease, a heart attack can ensue. Then there is the added problem of inadequate replenishment of the body’s water content, which results in dehydration that decreases blood volume and puts extra strain on the heart as it struggles to deliver more blood to the skin. If this attempt to regulate temperature fails, the body’s core temperature can rise to a level that damages organs and results in potentially fatal heat stroke. The  estimates close to half a million heat-related deaths occur annually in the world and these are expected to increase as global warming heats up.
While global warming is a hot topic these days, that wasn’t the case in 1961 when an episode of Rod Serling’s brilliant television series The Twilight Zone eerily foreshadowed the problems of climate change. In an episode titled The Midnight Sun, the Earth has suddenly changed its orbit, taking it ever closer to the sun. Most New Yorkers have headed toward Canada to escape the heat, but two women, an artist and her landlady, stay and suffer as life around them erodes. Water becomes a prized possession, electricity is spotty, and the women are threatened by a man who breaks in looking for water, having been driven insane by the heat.
Amazingly, a 1956 episode of Alfred Hitchcock Presents, Shopping for Death, also had a plot that involved a heat wave. A couple of insurance salesmen note most murders occur in hot weather and encounter a woman who is in a distraught mental state because of the heat. They fear her behaviour is going to trigger violence by her abusive husband. The men try to calm her down, but the heat ends up taking its toll and she is slain. Spike Lee in his classic 1989 film Do The Right Thing also focuses on heat as a driver of violence. This time, it is in Brooklyn, where conflict arises between African and Italian Americans during a heat wave. Sweaty bodies taunt each other with increasing ferocity, culminating in a tragic end.
Current crime statistics reveal  is not restricted to fiction. There are more killings, assaults, domestic violence and even online hate-mongering on hot days. Heat makes people feel miserable, but it may do more than that. As blood flow is redirected toward the extremities to aid in cooling, there may be reduced flow to the brain resulting in impaired delivery of oxygen and glucose. Both of these are needed for proper brain function and a lack can cause irrational thinking and cognitive deficits.
We were first alerted to that possibility by Dr. Cedeno Laurent, then at Harvard, who took advantage of a heat wave in Boston in 2016 and administered cognition tests to two groups of university students, one residing in an air-conditioned residence and the other in a building without that benefit. The average temperatures in the two dorms, 26.3 C and 21.4 C, were significantly different, as were the results of tests that measured word-processing speed and mathematical acuity administered every morning for 12 days. The air-conditioned students did better. Similar results were found by Prof. Jinsung Park at the University of Pennsylvania who examined performance on the Preliminary Scholastic Aptitude Test (PSAT) written by high school students across the U.S.
After gathering daily temperature data from weather stations across the country, Park determined scores were lower when the weather was hot, especially in schools without air-conditioning. It seems not only can AC reduce violence and improve efficiency in the workplace, it can even help us think better. For this technological breakthrough, we can thank engineer Willis Carrier, who in 1902 was asked to confront a problem that a Brooklyn lithographic company faced when its paper expanded and shrank in response to summer humidity and made printing on it a challenge. To solve the problem, Carrier invented a system that compressed ammonia to a liquid and then allowed it to evaporate, drawing heat from the surroundings. The air-conditioner was born. The public would first experience its benefits at the Missouri State pavilion at the 1904 World’s Fair in St. Louis.
How long did the folks in the musical have to endure temperatures that reached 110 degrees in the shade? As the show ends with the rainmaker leaving after being rejected by Lizzie, there is a clap of thunder and everyone on the stage is drenched with “rain.” Did the rainmaker finally succeed for the first time? We were left to wonder as we strode out into the hot New York streets hoping for rain.
