Study: N.H. Will Soon See Extreme Heat Like Southeastern U.S. If Carbon Emissions Don’t Decline

Jul 16, 2019

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A new study says New Hampshire and the nation will see far more days with dangerous heat over the coming decades – especially without more action to curtail climate change.

The study from the Union of Concerned Scientists looks at how different responses to climate change will affect the prevalence of extreme temperatures nationwide. It finds that historically, New Hampshire and most of New England have rarely seen the kind of heat that can pose serious health risks.

This study says the Granite State’s "feels-like" temperature, or heat index, has only topped 90°F a few days a year on average in recent decades. It says the state’s heat index has almost never topped 100°F, when sensitive populations and outdoor workers can begin to suffer heat stress or other related illnesses.

The new research says that will change by mid-century, even with rapid response to climate change. It says New England could become roughly as hot as the Mid-Atlantic, or parts of the Southeast, within decades.

By 2100, if emissions don't decrease, the study finds New Hampshire will see nearly 50 days a year with a heat index above 90°F. Around 10 to 20 days a year will feel hotter than 100°F, and at least one day a year will feel hotter than 120°F.

Erika Spanger-Siegfried is lead climate analyst for the Concerned Scientists.

“The kind of heat we’re looking at can really hurt people, and we don’t see this coming,” she says. “We’re barreling down that no-action, business-as-usual scenario, and we simply can’t – that’s not a future that anybody wants to live in.”

She says the projected heat is far more significant – and potentially life-threatening – in parts of the country that already run hot. And across the country, she says it will mean more air conditioning and electricity demand.

"If people in the U.S. – people around the world, really – are relying on dirty power sources to keep our indoors cool, we're essentially further heating the outdoors in the process,” Spanger-Siegfried says.

The study says regardless of future emission scenarios, the rise in extreme heat will require new infrastructure and other adaptations – especially in regions, like Northern New England, where society is not accustomed to such conditions. Spanger-Siegfried says this also means residents here will feel the change more acutely, even if it’s not as severe as in hotter parts of the country.