【Semi-dokyumento: Tokkun Meiki Dukuri】

Climate 101is a Mashable series that answers provoking and Semi-dokyumento: Tokkun Meiki Dukurisalient questions about Earth’s warming climate.

The Dust Bowl heat was terrible.

A potent nexus of events — extremely dry, hot weather exacerbated by poor farming practices that turned regions into scorching, dust-ridden wastelands — conspired to drive record high summer temperatures in the Central U.S. in July 1936. The heat killed some 5,000 people.

Yet even without the grisly human-made, "literal hell on Earth" Dust Bowl conditions, the National Oceanic and Atmospheric Administration recently announced that the 2021 meteorological summer (June-August) matched 1936 as the hottest summer on record in the continental U.S. Over 18 percent of the Lower 48 states experienced record warm average summer temperatures, the agency said.

Crucially, continuously rising temperatures from human-caused climate change played a dominant role in this year's heat, which saw either record or unusually high temperatures in the West, the upper Midwest, and the Northeast. (The South mostly experienced normal summer temperatures, in part because it rained a lot, which has a cooling effect.)

Warmer overall global temperatures boost the odds for extremely hot summers, which then drive other climate impacts like more severe wildfires and more intense deluges. The climate has changed significantly since the Dust Bowl years, and extremely hot summers, consequently, will grow more common.

"From the 1930s through today, mean temperatures have already risen quite a bit over the continental U.S.," explained Aiguo Dai, a professor of atmospheric science at the University at Albany. This results in more warmer-than-normal, if not record-breaking temperatures, he said. (Global temperature rise has accelerated in the last 40 years, and Earth's seven-warmest years on record have all occurred since 2014.)

Sure, heat waves are normal. But when you boost background warming, "it gives you extra oomph," said Sean Sublette, a meteorologist at Climate Central, an organization that researches and reports on climate change. "That takes you places in the climate record that you haven't been before." (California, for example, just had its warmest summer on record.)

The warming in 2021 is starkly different in another major way, too. Today's global warming is a globalphenomenon, impacting the entire world. But in 1936, the record Central U.S. heat was limited to just half a percent of Earth's surface. This limited warming spell is shown in the map below, which was created and tweeted by climate scientist Brian Brettschneider.

"It was a very localized phenomenon," said Dai.

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On a global level, the 1936 summer was largely unremarkable: It ranks as the 83rd warmest since 1900. But in the Central U.S., the triple-digit heat was still merciless.

Destructive farming practices, like overplowed fields that created fine particulate dust, combined with the widespread removal of native grasslands and repeated droughts, resulted in gnarly, infamous dust storms.

"You got windswept plains and powdery soils," said Sublette. Then, during a particularly hot summer, all the sun's energy went into warming the dry surface, as opposed to evaporating moisture from plants — either native plants or unplowed crops. "If you've got no crops, all your energy is going into heating the dry ground," explained Sublette. This boosts temperatures.

"[The Dust Bowl years] would have been hot anyway, but that extra bit from farming made it hotter," he said.

The good news is the U.S learned from these dire, dusty conditions, making them far less likely. "As a result of the 'Dust Bowl', new farming methods and techniques were developed, along with a focus on soil conservation," explained the National Weather Service. "This has helped to avert or minimize the impact of a prolonged drought."

Yet today's warming isn't as easily remedied. It's largely driven by the extraction and burning of ancient, decayed carbon-rich creatures — aka "fossil fuels"— that have driven CO2 levels in the atmosphere to their highest levels in some 3 million years. With such high (and still growing levels), the planet will continue warming for at least a few more decades. That's why earth scientists repeatedly encourage civilization to rapidly adopt energy sources that don't pollute the atmosphere, like powerful wind turbines.

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Slashing carbon emissions today will help avoid the worst impacts of climate change, scientists say. But atmospheric physics demand there will still be more U.S. summers that match, and inevitably eclipse, this summer's temperatures in the coming years and decades. Later this century, 2021 will be considered a relatively cool summer, noted Sublette. Though how much cooler is up to us.

"We're on a trajectory that's largely going up," Sublette said. "It is going to get hotter."

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