【Hostess in Heat】

Climate 101 is Hostess in Heata Mashable series that answers provoking and salient questions about Earth’s warming climate.

Like nearly the entire planet, the hottest place on Earth is growing hotter.

On Sunday, the National Weather Service reported a 130 degree Fahrenheit temperature in Death Valley, Calif., which is likely the highest temperature ever accurately recorded on Earth. (Many meteorologists agree that earlier records, including a wild 134 F reading in Death Valley in 1913, weren't reliable or even possible.)

This new heat record, which the World Meteorological Organization will verify over the coming weeks, occurred during a widespread California heat wave. Like all intense heat waves today, Death Valley's record heat was an extreme weather event amplified by climate change.

"I believe this 130 [F] will verify and it will be the hottest temperature ever recorded on Earth," said Jeff Weber, a research meteorologist at the University Corporation for Atmospheric Research. "That is quite significant."

[Note: The National Weather Service forecasts temperatures to reach 132 F on Monday, which would smash this tentative brand new record.]

Heat waves are natural. They would happen if humanity didn't exist. But when society turns the climate dial — by loading the atmosphere with the potent heat trapping gas carbon dioxide — heat waves inevitably grow hotter.

"Heat wavesare warmer because of climate change," said Michael Wehner, a scientist who researches extreme weather events at the Lawrence Berkeley National Laboratory.

The evidence is everywhere. Generally, more heat in the atmosphere results in more broken high temperature records. In 2019, for example, 364all-time high temperatures were set, compared to just 70all-time lows.

"As the climate changes into a warmer climate we do expect to see more extreme warm temperatures," Ahira Sánchez-Lugo, a National Oceanic and Atmospheric Administration climatologist, told Mashable in December. "That’s what we’re seeing, and that’s what the data are showing."

The rare, most intense heat waves in California are some 3 F to 4 F warmer than they otherwise would be without human influence, Wehner found. Before Sunday, the highest August temperature ever recorded in Death Valley was 127 F. Now it's 130 F.

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The large-scale weather pattern that enabled this Western heat wave is called a "heat ridge" or "heat dome." It's a vast zone of high atmospheric pressure, typified by clear skies and dry weather, that can stay locked over a region.

There are few clouds to block sunlight, nor is there any moisture for the sun's energy to evaporate from the ground. Without any moisture, the sun just incessantly heats the surface. "It’s this complete void of moisture that allows these temperatures to build," said Weber. (Though over the weekend some tropical storm activity from the Pacific Ocean streamed into California, bringing weird, rare thunderstorms to parts of Central California, San Francisco, and Northern California).

Overall, this heat dome has stayed locked in place over the West for about a month, breaking temperature records in the nation's hottest city, Phoenix. Weather systems typically travel from west to east across the U.S., but nothing has budged this formidable heat dome. Over time, the persistent heat builds on itself: Nights grow warmer, so the day starts anew with unusually warm temperatures, which then amplify. "It's that persistence that really aggregates," emphasized Weber.

When you add a stagnant heat wave to a warming climate, you can get record heat.

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This doesn't bode well for the Golden State's fire season, with land that's naturally primed to burn. Higher temperatures accelerate the drying out of vegetation, resulting in fires that spread faster and burn more area. Wildfires in the U.S. are on average burning twice as much landas they were in the 1990s. And in the West, modern blazes are burning for weeks, not days, longer.

Nine of the top 10 largest wildfires in the state’s history have occurred since 2003.

What's more, millions of Californians live in inland areas, the places that experience the worst heat. Stockton, for example, hit 113 F Sunday. Many people, particularly those who work outside and in the state's booming agriculture sector, can't easily escape the heat, and heat-related illnesses.

"Impacts of heat waves are unevenly distributed," said Wehner, noting agricultural workers are already subjected to serious infections like Valley Fever. "The bulk of bad impacts are on the poorer of our fellow Californians."

The latest heat event and associated record in Death Valley (once confirmed) show temperatures are growing more extreme. How much more extreme will they get? That's up to the most unpredictable factor of the global warming equation: us.

"As the climate continues to warm, those numbers get bigger," said Wehner. "Depending on what path we take, that determines how much warmer these heat waves will get."