Pope Francis has proclaimed climate change a fact, stressing our moral duty to correct it. The pontiff titled his encyclical Laudato Si, or "Be Praised," a phrase taken from "Canticle of the Sun," composed by the wandering naturalist and pioneering ecologist, St. Francis of Assisi.
I agree we are experiencing man-made climate change. But much of the change might arise from factors until now unconsidered. To make my case, I humbly invoke the 14th-century English Franciscan friar William of Occam and his principle of lex Parsimoniae ("law of parsimony"), the theory we know as "Occam's Razor."
The principle holds that, between competing hypotheses, the one based on the fewest assumptions is apt to be the correct one.
My hypothesis regarding global warming, called Personal Climate Change, requires no experts, voluminous studies, "hockey stick charts," or intergovernmental panels. In its parsimonious way, it locates the heart of climate change, not in the ozone level or longtime weather patterns but with us humans, our bodies, and daily behavior. The problem is not global, but as local as the body you inhabit.
Over the last half century, Americans' "personal climates" have undergone a transformation. Two crucial developments factor in the rise of Personal Climate Change: air-conditioning and changes in clothing styles.
Consider how cold it is, come July, in homes, office buildings, malls, and restaurants. Notice how the ubiquitous T-shirt, and its many and various descendants, leaves the skin exposed, offering no insulation from the sudden heat blast as one steps outdoors.
The T-shirt's popularity dates from post-World War II. Originally an undergarment for warmth, the T-shirt on its own became standard-issue military wear that allowed millions of personnel to keep cool in the sweltering tropics.
Postwar T-shirts became an essential ingredient in young America's year-round informal uniform. The skimpy garment has a triple effect on its wearers - making them feel colder in air-conditioned buildings, hotter once outdoors, and hypersensitive to the acute temperature contrast between indoors and out.
In the 1950s, air-conditioning's chill became pervasive in America's great indoors, notably in the South and Southwest. Soon AC was everpresent across the land. In the air-conditioned '50s, the word cool became the new hot.
Over the last 30 years, Americans have gravitated to the Sun Belt's sprawl of treeless, shadeless suburban conurbations. In this Deserta suburbanica, the American Dream morphs into Henry Miller's Air-Conditioned Nightmare. Arizonians live half the year in air-conditioned lockdown - waking in 70 degrees, driving in the 70-degree climate of their cars, and working in 70-degree offices. In this artificial paradise, the real, natural climate becomes notional, abstract, terra incognita.
To one unnaturally cooled, nature feels unnaturally hot. The perception of global warming partly stems from the lack of air-conditioning we find outdoors. Literally, we lose our cool.
Just as Americans started dressing down in the 1960s, on went their T-shirts, and off went their hats. The dramatic decrease in the wearing of hats - which keep you warm in winter, and cool in summer - was accompanied by an equal and opposite increase in head colds and a skyrocketing demand for cold remedies. Cool begot colds.
Then there is the "windchill" factor, a 1960s innovation, now standard in winter weather reports. Cold will no longer suffice - too vague. "Minus 10 with the windchill," we mutter, venturing hatlessly into frigid weather, body heat escaping from our bare domes. Windchill statistics let us suffer the cold more knowledgeably, just as with global warming we feel knowledgeably warmer. Ours is, after all, a suggestible species.
Personal Climate Change - effected by refrigerated environments, intensified by thin, weightless, sleeveless clothing and hatless heads - predisposes Americans to warm to the concern about global warming. It feels true.
I do not dispute climate change, so lay down your hockey stick charts. I wonder, however, if our profoundly altered personal climates have made us the climate change we believe in. Personal Climate Change, a theory rich in parsimony, does not solve Global Warming. Yet, it just might enlarge our understanding - if only to a degree.
George Ball is chairman of W. Atlee Burpee & Co. and past president of the American Horticultural Society.