Spring has come and with it a familiar sadness. In the street below me, young women walk to yoga class—you can tell by their rolled-up mats—with arms that are bare for the first time in months. The thin limbs of the tree outside my window bristle with buds, tender pellets of renewal that would stir Van Gogh.

The wheel of life has turned full circle. But to some of us—those cursed with sensitivity—the change in temperature serves to remind that beneath the shifting finery of Mother Nature lurks a pair of foul-smelling undergarments that have been around, unchanged, nigh on several centuries. I refer to the Celsius and Fahrenheit scales.

Now, I know what you're thinking: You're thinking, "Sorry—what?" Nonetheless, that happens to be the question I have decided to address on this bright, inexpressibly balmy afternoon.

In the professional football community, there is a saying, often uttered in training camp, that a coach who enters the season with a choice of starting quarterbacks is a coach with no quarterback at all. A quarterback, runs the theory, is like a king in that his authority and his ability to lead flow directly from there being one of him. A team with two first-class, viable starting quarterbacks is therefore like a nation with two kings: a dysfunctional hotbed of dissent and unrest doomed to implode into what Shakespeare called "the intestine shock/And furious close of civil butchery"—the only quote by the Bard this correspondent has ever been able to remember, hence my practice of grandly unleashing it at the merest opportunity.

And so it is with our two temperature scales. Generally speaking, the planet favors Celsius, with the significant exception of the United States and the insignificant exception of Jamaica. But the problem isn't one of international favor. If either Celsius or Fahrenheit were actually getting the job done, nations could agree to disagree, much as they have done over kilometers and miles.

No, the problem arises in those many countries, ours among them, where the two scales coexist. Here in the States we use Fahrenheit for weather, Celsius for science, Fahrenheit for body temperature, and Celsius—often—in our discussions of global warming. Seems fairly straightforward all written down like that, but there's more than enough overlap between the discourses to induce a permanent state of wariness in all discussions of matters relating to temperature. However comfortable any given American may personally feel within either the C or F system, he or she must still make allowances for the thermal ambiguity of others. No old man beside a campfire can ever thoughtfully poke the embers with his stick and launch into an epic yarn with the words, "It was 34 degrees that morning . . . ."

Without more information, listeners have no choice but to brace themselves for both Lawrence of Arabia and Doctor Zhivago. Even when there's hardly any ambiguity—a blow-dried weatherman promising 65 degrees for the weekend—there is too often a fleeting sensation of uncertainty, much as when one approaches a glass door with the word "LLUP" or "HSUP" written on it, before the instruction is decoded to the satisfaction of the unconscious.

For a nation with as much invested in its reputation for common sense and decisiveness, I would argue that this constant background dithering is a dangerous drain on mental energy.

How did we find ourselves in such a predicament?

The culprit, of course, is History.

Back in 1724, the world measured temperature, when it measured it at all, by the eponymous scale of one Ole Christensen Rømer. Rømer was the man who in 1676 had first measured the speed of light, and his temperature scale, when he unveiled it in 1701, was a predictably abstract affair, of use principally to scientists. Water, Rømer declared, would henceforth be said to boil at 60 degrees and to freeze at . . . at . . . well, at 7.5 degrees. Yes, that's right: Seven and a half. Zero, of course, he reserved for the temperature of ice mixed with salt, almost as if the physical laws by which men lived their lives were but a pale shadow of that deeper truth: the recipe for a truly kicky margarita.

To a young German physicist named Daniel Gabriel Fahrenheit, the cold-blooded Rømer scale seemed to cry out for a sister scale, if not an outright replacement, usable by the general public. His alternative, published in 1724, was a masterpiece of populism, a temperature scale for the masses. Rather than worrying about what temperatures made various substances do what under laboratory conditions, Fahrenheit simply used 100 degrees to denote the highest temperature reached with any kind of regularity in Western Europe, and 0 degrees for the lowest. The scale was an instant hit, and for good reason. For the first time in history, a generation was able to know the thrill of watching temperatures climb toward 100 degrees over the course of a sweltering summer.

Better still, the Fahrenheit scale made it possible at last to generalize about temperature in a way that resonated with the human experience. It's difficult for us future dwellers to imagine, but prior to 1724, statements like "It'll stay in the 60s through the end of the week, and on Saturday? Dust off that barbecue, people, we're headed into the 70s. Chuck? Yolanda?" were simply unknown. You could say it was hot. You could say it was cold. You could even say it was 13.75 degrees Rømer, but the romantic and beautifully intuitive concept of a heat wave in the 90s was futurespeak.

Indeed, Fahrenheit's gift to the world was so liberating and transformative that people were willing to overlook its glaring flaw. At lower temperatures—those one might encounter during, say, winter—the intuitive poetry of the Fahrenheit scale disappears. You don't need to be a hydrologist to appreciate that there's a qualitative difference between the world at 34 F and the world at 31 F and that the Fahrenheit scale does nothing to reflect that. Glance at Fahrenheit's biography, and the reason for this jumps out. Although he lived and worked in Germany, Fahrenheit was born in Danzig, Poland, later named Gdan´ sk, the icy harbor on the shores of the Baltic whose weather would provide such a poignantly bleak backdrop to the Solidarity protests of the 1980s. To a native Danzigian, the temperature at which water froze was a thing of no consequence, certainly not when compared with the majestic, definitive coldness of his boyhood winters, and so Fahrenheit assigned it the not otherwise distinguished number of 32.

This forgivable error of solipsism left the door ajar for Swedish astronomer Anders Celsius. His centigrade scale, debuting in 1742, hitched its wagon to the freezing point of water and hung out its shingle (this might be a good moment to point out that there's a crucial difference between the stylistic sin of mixing metaphors and the stylistic choice of simply using two metaphors in hideously close proximity) on water's boiling point. Celsius, for the record, declared that the freezing point be known as 100 C and the boiling point as 0 C, but this silly arrangement was promptly reversed after his death in 1744.

Since then, the two scales have angled for supremacy like boxers circling each other in the ring, both bleeding, both exhausted, neither able to land a knockout punch. Celsius—as any number of foreigners will argue until they're blue in the face—is the simpler and more logical system. Fahrenheit supporters hardly feel the need to say anything, so lost are they in reveries of those honeyed, literary summers of love and lemonade, the thermometer needle drifting lazily between 80 and 90.

Enough is enough. We stand blinking in the dawn of what promises to be our most challenging century. We need our wits about us, our ducks in a row, and our affairs more in order. Fahrenheit and Celsius have served us well over the years, all things considered, but we owe nothing to their memory. Instead, we owe it to ourselves, if we're even to stand a chance, to send both to their reward and invent a wholly new system with which to walk, sure-footedly, into the future. But there's the rub. Who alive has the rigor and humanity to end this nightmare of our divided loyalties?

To cynically and viciously misparaphrase Tina Turner, we do need another hero. And quickly, before summer is upon us. We may make it through this spring with only this pair of blunderbusses for protection. But as Stevie Wonder suggests, there are few things more urgently demanding of a fully functional temperature scale than July.