It has been 110 years since Willis Carrier flipped the switch on the first unit to change indoor air temperature. (istockphoto)

The air conditioner turns 110 today. The anniversary year is almost the feels-like temperature of Washington, D.C. — all the more reason to quietly thank air-conditioning inventor Willis Carrier — or is it?

It all started July 17, 1902, when, as the New York Times reports, with the flip of a switch, the first unit to change indoor air temperature began cooling the top floor of a Brooklyn printing plant. While others had focused on merely cooling the air, Carrier focused on the real key: controlling humidity. He discovered that, by forcing air over pipes filled with cool well water, which he eventually refrigerated, he could control the temperature on the small printing plant’s upper floor, where the humidity was impeding the printing process.

In 1911, Carrier released the “Rational Psychrometric Formulae,” which would come to be known as the Magna Carta of air-conditioning, making him a household name. Carrier went on to found the eponymous company known for heating and cooling units the world over.

Carrier’s inventions over the next 50 years eventually earned him the nickname “The Father of Air Conditioning.” Notably, 12 years after his discovery, as suffragettes petitioned for the right to vote, Carrier hired Margaret Ingles, the nation’s first female air conditioning engineer. Ingles would go on to write Carrier’s biography, which was published in 1952 — two years after the inventor’s death while on a trip to New York City. He was 73.

Beyond founding a 100-plus-year old company, Carrier’s invention can be credited with fundamentally changing the U.S. economy, increasing productivity by giving American workers a respite from what is at times debilitating heat. But, as The Post’s Brad Plumer outlines, there’s a darker, hotter side to the air conditioning coin: The current rate of cool-air consumption is unsustainable, with countries such as India and China burning coal to meet their populations’ energy demands, including for — you guessed it — air conditioning.

If all of these countries keep burning coal to satisfy demand for indoor cooling, the result will be more carbon dioxide in the air. (The newer, ozone-friendly HFCs used in the units are also highly potent greenhouse gases.) That means a hotter planet overall, which will, in turn, require even more air conditioning to survive. ... The current “freak heat wave” will become the norm for one-sixth of the year in D.C. (That’s in addition to all the other climate consequences — sea-level rise, droughts, agricultural disruption — that could prove far more difficult to adapt to.) In our endless quest to cool ourselves, we’ve managed to heat the world.

Plumer’s blog post is eerily similar to a Sept. 4, 1988, piece penned by Brock Yates for The Post (pdf). Yates’s piece starts with a celebration of Carrier’s invention, but by the end, his tone, much like Plumer’s, turns markedly dour:

For most of this century, we have considered air conditioning a blessing for all mankind. But that blessing may be turning into a curse that could accelerate the day when, if the doomsayers are correct, the whole planet resembles downtown Houston in August.

So Willis Haviland Carrier may deserve one round of applause for his invention. Bus as our ecosystem becomes more and more vulnerable, perhaps we ought to wait a while before calling for an encore.

The increasingly janus nature of Carrier’s invention is, perhaps, worth thinking about as we yet again raise a chilled glass in the cool comfort of our homes as the temperature continues to climb outside.

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