Brian Laird on WNYC, and now we continue our WNYC Centennial series,

A Hundred Years of a Hundred Things.

We're going to get to it 100 years of air conditioning, but just

to recoup Monday segment, the 10 warmest years and the historical record have occurred in the

last decade. We spoke about it when we did a crawl through temperature averages over the last

hundred years as part of this series on Monday.

Here's just 20 seconds of Monday's guest to help take us to the air condition and conversation.

Climate scientist Michael E. Mann, professor and director of the Center for Science Sustainability and the media at the University of Pennsylvania, as he explained to us just how rare the current

temperature curve is and why it wouldn't happen without human-caused climate change. People say,

oh, well, maybe we're just unlucky. We've had a number of warm years. You know, it's an unlucky

role of the climate dives. You can calculate in the absence of

human-caused warming, how likely something like that would be. And we're talking like one in 50,000-year

events, something that is extremely unlikely to have been observed in the absence of human-caused

warming. So that was Thing 5 on Monday show. Now we're up to Thing 6,

which yes, follows suit and is air conditioning. One hundred years ago, in 1924, a department store

in Detroit called J.L. Hudson's became the first to use air conditioning to cool its stores. Sales ticked up immediately,

and the demand for air-conditioned public spaces soared, most notably, movie theaters. Over the

decades, air conditioning became ubiquitous in American homes, as we know, also transportation,

also other shared spaces. But it also represented a problem.

The chemicals used in the cooling process were the same chemicals that contribute to the

depletion of the ozone layer. Joining us now to talk about air conditioning's rise to prominence

in American culture, decade by decade, through how recently having ACs has gone from being a luxury

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