Those scrolling through social media during a heat wave may have come across a tidbit often used to downplay human-caused climate change: Many U.S. states and cities experienced some of their hottest temperatures on record in the 1930s, setting records that remain today. The incredible heat mark that exists.
The key context that is often overlooked is that the 1930s was the decade of the Dust Bowl, the horrific result of relentless overdevelopment of the Great Plains, followed by natural ocean circulation that favored years of drought, which coincided with the Great Depression. It was an American catastrophe that was nearly a century old but receives little attention today, and memory of it is quickly fading.
An excellent summary of the Dust Bowl from the University of Nebraska points to some of the sociological factors that contributed to the disaster:
“Proponents” of the region wanted to promote settlement and offered glowing but inaccurate descriptions of the Great Plains' agricultural potential. In addition to these inaccurate information, most settlers had little money or other assets, and their farming experience was based on conditions in the wetter eastern United States, so their choice of crops and farming methods were often inappropriate for the Great Plains. But the earliest settlements occurred during wet cycles when the first crops flourished, thus encouraging settlers to continue a practice they later had to abandon.
Three multi-year droughts occurred between 1928 and 1942 with little interruption. During those harsh years, much of the topsoil in the central United States was blown away by the wind. The exposed landscape allows for maximum warming from the summer sun, which in turn helps to intensify the prevailing deep atmospheric heat. Daily weather patterns sometimes push dust and heat all the way to the East Coast.
Hundreds of thousands of poor farmers came to California from the Great Plains in the hope of finding work, an immigration immortalized in the critically acclaimed book and film “The Grapes of Wrath.”.” [From Bob Henson: My own mother grew up in western Oklahoma during the Dust Bowl, and I vividly remember her telling me how she sometimes walked to school with a wet handkerchief over her face, simply to be able to breathe without inhaling lungfuls of dust.]
How dust storms combine with natural ocean circulation to create record heat
There is good evidence that the hot weather of the 1930s was caused in part by excessive planting and farming that left the land dry.
Using computer modeling, Richard Seager of Columbia University and colleagues found that landscape degradation from dust storms interacted with ocean-forced drought to intensify heat patterns and move them poleward. A 2022 modeling study led by Gerald Meehl of the National Center for Atmospheric Research found that dust storm landscapes may help spread extreme heat to other parts of the Northern Hemisphere. The paper states:
It was not until the twenty-first century that populations in these parts of the Northern Hemisphere experienced extreme heat comparable to those experienced in the 1930s. This demonstrates that humans have impacted temperatures and heat extremes in the Northern Hemisphere through catastrophic and unprecedented regional land use practices in the Great Plains, and suggests that intense regional droughts in the future may influence heat extremes on a hemispheric scale.
Although the effects of dust storms may have helped spread heat and drought from North America to Eurasia, much of the Earth was still much cooler than it is today. When you compare global and U.S. temperatures from the 1930s to the early 21st century, as scientist Andrew Dessler did in a Climate Edge post (see Figure 3 below), it's clear that the U.S. wasn't really part of the global heat at that time trend, and it definitely is now.
If anything, the 1930s were less a comforting story about the changing nature of nature than a cautionary tale about what was going on. able happened – a saga of hubris and ignorance of how humans’ interactions with the natural environment pave the way for profound climate impacts.
1936 heat record
Extreme weather historian Christopher Burt documented the scorching heat of July and August 1936 in detail in a 2018 article in Weather Underground. Dozens of U.S. states and cities hit all-time high temperatures (the highest readings officially observed at a specific location). The hot weather spread to south-central Canada, with temperatures in Winnipeg, Manitoba soaring to a record high of 108 degrees Fahrenheit. Here are some of the all-time highs set or set in major U.S. cities in July 1936:
New York City, NY: 106°F (July 10)
Baltimore, MD: 107°F (July 10)
Columbus, Ohio: 106°F (July 14)
Louisville, Kentucky: 107°F (July 14)
Des Moines, Iowa: 110°F (July 25)
Minneapolis, Minnesota: 108°F (July 14)
Bismarck, North Dakota: 114°F (July 6)
Omaha, Nebraska: 114°F (July 25)
The following states also reached record highs in July 1936 and remain at record highs today:
Indiana: 116°F (Collegeville, July 14)
Iowa*: 117°F (The Atlantic and Logan, July 25)
Kansas: 121°F (Fredonia, July 18; Alton, July 24)
Maryland: 109°F (Cumberland and Frederick, July 10)
Michigan: 112°F (Mio, July 13)
Minnesota: 114°F (Morehead, July 6)
Missouri: 118°F (Clinton, July 15; Lamar, July 18)
Nebraska: 118°F (Hartington, July 17; Minden, July 24)
New Jersey: 110°F (Runyon, July 10)
North Dakota: 121°F (Steele, July 6)
Oklahoma: 120°F (Alba, July 18; Altes, July 19)
Pennsylvania: 111°F (Phoenixville, July 10)
West Virginia: 112°F (Martinsburg, July 10)
Wisconsin: 114°F (Wisconsin Dells, July 13)
*The 118°F reported by Keokuk 2 on July 20, 1934 was almost certainly wrong. No other location in Iowa had temperatures above 112°F that day, with the NWS Keokuk location recording just 109°F.
The international disaster database EM-DAT ranks the 1936 North American heat wave as the 11th deadliest event in modern world history, with 1,693 fatalities. However, that total is an underestimate because it only includes deaths reported in Illinois in July (1,193) and an estimated 500 deaths in Canada. Burt pointed to news reports from St. Louis, Minneapolis and Indiana that there were 814 heat-related deaths in those areas alone. A U.S. Department of Commerce summary of mortality statistics (see PDF) lists heat-related deaths in the United States at 4,678 in 1936, compared with 728 in 1935.
As Bert said:
… Nothing comparable to the heat wave of the summer of 1936 had ever occurred in the continental United States before or since. Movie theaters are one of the few places where you can use air conditioning to at least temporarily relieve stress.
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