Hot days ahead?

A new report from the Union of Concerned Scientists predicts an increase of “dangerously hot” days nationwide through the next century, with New Hampshire facing up to 49 days per year with a heat index above 90 degrees Fahrenheit by 2100.

The report — which is accompanied by a peer-reviewed study on its methodology — released today combines 18 climate models to look at extreme temperatures, and adjusts the forecasted heat spikes based on how much global action is taken on climate change.

The authors explain their focus on certain degree thresholds, and how extreme heat poses risks to different populations, such as the elderly, children and outdoor workers.

Founded in 1969 at the Massachusetts Institute of Technology, the Union of Concerned Scientists is a nonprofit science advocacy organization with more than 200,000 members.

The heat index — or “feels like” temperature — of 90 degrees marks the point where outdoor workers generally begin to experience heat-related illnesses, according to the report.

Heat indexes of 100 and 105 degrees were also included because they trigger the National Weather Service’s heat advisories and excessive heat warnings.

The report also accounts for different regions of the United States and gives state-specific data, which are outlined further in regional news releases and full spreadsheets.

New Hampshire could see an increase from an average of three days annually above a 90-degree heat index in recent years to 23 by mid-century and 49 by 2100, according to the report. But if international action is taken to keep global temperature increases under 2 degrees Celsius, the number of dangerously hot days annually in the Granite State could be kept to 17 by century’s end, the authors note.

Under the status quo, the frequency of heat indexes exceeding 100 and 105 degrees — currently rare enough in New Hampshire to average out to zero, annually — would climb to 17 and 10 by 2100, respectively, the study predicts.

“The rise in days with extreme heat will change life as we know it nationwide, but with significant regional differences,” said Rachel Licker, a co-author of the report who was a climate scientist with the Department of State before joining the Union of Concerned Scientists, in a news release. “For example, in some regions currently unaccustomed to extreme heat — those such as the upper Midwest, Northeast and Northwest — the ability of people and infrastructure to cope with it is woefully inadequate.”

To boil down climate studies to the lay person, Keene State College environmental science professor Nora Traviss — who did not work on the report or have access to it before its publication — tells locals to think back to how the seasons evolved in past decades. She said to look at the intensity of ticks and this year’s airborne allergens — all of which she said stem from climate change.

“Scientists, we get caught up in being overly cautious about how data is presented,” Traviss said, “and so it’s important to ... get people to think about what’s changed in the last 20 years.”

Extreme heat does not affect everyone equally, she noted.

“Things like heat exhaustion and heat stress, exacerbation of asthma, pollen, ticks — all these things disproportionately impact the most vulnerable among us, so children and the elderly,” Traviss said. “So resources will need to be allocated so we can be prepared for that.”

Keeping cool

Meanwhile, local heating and cooling professionals say a rise in sales has come on the heels of the more severe heat waves in recent years.

“The demand has gone up, and so, therefore, of course there’s an increase [in sales of air-conditioning units] that goes along with that,” said Adrian Pinney, owner of Pinney Plumbing & Heating in Swanzey.

Pinney said customers often ask him about climate change.

“I don’t have an answer to all of the science,” he said, adding that he finds that meteorologists are not convinced by all the conclusions around the topic. “... By the same token, I’ve been doing this as a career since 1972, and I know that we are in a belt of warmer winters and hotter summers — eh, I don’t quite see it [as much in the summer], but they go hand in hand — something’s different. Whether it’s cyclical or not, I don’t know.”

He noted that customers, however, weigh the severity of recent heat waves very heavily in their purchasing decisions.

By February of this year, he said, orders for air-conditioning units and central air installations were already coming in from people recalling last July’s heat wave.

Pablo Fleischmann, co-owner of Green Energy Options in Keene, said his business has pushed more into the cooling sector since moving to a larger building on Roxbury Street in 2017.

The company sells solar energy products and wood stoves, and also helps customers with a litany of energy-efficient home heating projects, according to Fleischmann.

“In general, our business has grown,” he said. “... When we decided to grow, we decided to take on mini splits as a product we sell.”

Mini splits — which Pinney also offers — are external units that evaporate or condense the outside air for cooling and heating. A mini split can heat and cool individual or multiple rooms and tends to be quiet, while conventional air-conditioning requires either a louder window unit or a central air system involving the whole building and relying on ducts.

Fleischmann said his clientele is diverse by age; younger customers tend to have “an awareness” about climate change that drives them to the business, he explained, but the economic and comfort advantages of his products appeal to anyone.

Still, he said a clear climate pattern has led to the increase in demand for cooling, and that from a more cynical “doomsdayer” perspective, cooling is the smarter long-term investment than heating.

Yet aside from climate change, both Fleischmann and Pinney said another important factor in their business is a social change — customers’ general expectation for air conditioning in the modern world.

“When I was a kid — I grew up in Dublin — you came home from a hot day at school or a hot day at work ... you all jumped in the back of the pickup truck, and you ran up and went swimming for an hour and cooled off in the lake that was lucky to be 55 degrees,” Pinney chuckled, “and you were sort of good for the night.

“What’s different today is that we get up in the morning, and we go to work in an air-conditioned office, and we rode there in our air-conditioned car, and we go out to dinner in an air-conditioned restaurant.”

Jake Lahut can be reached at 352-1234, extension 1435, or Follow him on Twitter @JakeLahut.