Hot Summer Nights: Climate Change Really Warms The Triad After Dark | Local

GREENSBORO – Summer days in the Triad look pretty much like they did a century ago.

Summer nights? Let’s just say those sleepy porches that still made scorching nights tolerable in 1922 would have seen much more use in 2022 if it weren’t for the luxury of air conditioning.

Blame it on the “wet cover effect” of climate change, experts say.

While the annual average high temperatures in the Triad for June, July and August – considered the climatological summer by weather scientists – have remained roughly the same for the past 100 years, the decadal average lows by decade have soared nearly 4 degrees, according to historical data from Greensboro.

For long-term comparisons, the Greensboro data is the most comprehensive because it is the longest continuous record of official National Weather Service information available for the triad, and grouping the statistics into 10-year blocks minimizes the influence of single years with extreme highs or lows.

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The average summer low temperature in the Triad has increased every 10 years since 1953-62, from about 65 degrees to 68.5 in 2013-22.

Meanwhile, the average daily high temperature of 86.8 over the past 10 years was less than half a degree warmer than in the mid-20th century.

According to experts, the temperature contrast between night and day is the result of a self-perpetuating weather pattern shaped by climate change.

“Generally speaking, the faster rate of increase in nighttime temperatures is an expected result of increasing concentrations of greenhouse gases that are driving the global warming that we are experiencing,” explained Thomas Maycock, chief information officer. scientific public at the North Carolina Institute for Climate Studies. in Ashville.

The buildup of greenhouse gases — mostly carbon dioxide from burning fossil fuels like gasoline, natural gas and coal — is driving up temperatures. This heat often generates more humidity and, therefore, increased cloud cover.

“That’s true day and night, but during the day clouds also have a cooling effect because they reflect sunlight,” Maycock noted. “This cooling effect doesn’t apply at night, so you’re just left with the electric blanket effect.”

Forecasters also use the dew point – which measures the absolute amount of humidity in the air rather than a percentage – as a “first guess” for predicting nighttime temperature, said Carl Schreck, a researcher at the Institute for Climate Studies.

A warmer atmosphere means more humidity, higher dew points and higher nighttime lows,” he explained.

The trend of hot summer nights continued this year, when the average daily low temperature of 67.8 was nearly 2 degrees above the historical average since records began for Greensboro in 1903. The average daytime temperature, meanwhile, was 1 degree higher.

In the Triad, 15 of the 20 summers with the highest average nighttime temperatures since 1903 have been in this century, with 2022 tied for 12th. Overall, 2022 was the 17th hottest summer on record for the Triad.

However, in terms of average high temperature, this summer ranked 37th, indicating just how much nighttime weather is driving global warming. Although probably less noticeable than extreme daytime heat, what happens while most of us sleep can also have a significant impact on our lives.

Hot summer nights prevent the body from cooling down sufficiently in extremely hot weather, especially for those who work outdoors during the day and do not have air conditioning at home, making them more susceptible to heat-related illnesses.

Extremely hot nights also increase energy consumption and, therefore, electricity bills.

“When we have long days with very high temperatures and limited cooling at night, it forces air conditioners to work harder around the clock and our grid to work harder,” the Duke Energy spokesperson explained, Jeff Brooks. “So we often see higher usage trends when warm spells also include warm nights with limited cooling.”

Duke experienced this kind of situation in mid-June, when customers in central and western North Carolina and upstate South Carolina broke electricity demand records of one hour twice over a period of three days.

While the new norms were set in the early evening in June as residents turned on home air conditioners after their commute, those two nights were the hottest of the month in the Triad.

The Triad has seen a spike in extremely hot nights over the past 20 years, noted Corey Davis, a Kernersville native and assistant climatologist at the North Carolina State Climate Office. In the 1970s and 1980s, the region experienced a total of a dozen nights when temperatures never dropped below 75 degrees. Since 2003, the Triad has experienced 60 nights with low temperatures of at least 75.

“These warmer extremes are clearly occurring more often, and future projections suggest that these very hot nights could become a regular part of our summer weather – occurring 10 to 20 times a year in Piedmont by 2050,” said Davis.

These predictions are part of the 2020 North Carolina Climate Science Report, authored by 15 state-based climatologists. The report goes on to project that temperatures in North Carolina’s Piedmont could stay at 75 degrees or higher nearly every summer night by 2100 without a significant reduction in greenhouse gas emissions.

Even with aggressive efforts to reduce emissions, summer lows of at least 75 degrees can be expected nearly 40 times in some years by the end of the century, the report said.

For many Triad members, the continued warming will likely cause summer breezes to blow through our windows as we slip into a slumber of little more than a quaint memory.

Just like those sleeping porches.

Teresa H. Sadler