"The prof" follows, business-suited, in the form of Professor Ian Poll, and leads me into a spare conference room. A couple of commuter-sized jets are parked in view beyond windows on one side, from where high-pitched bursts of drilling interrupt our dialogue. As much as I might wish it, Ian Poll does not play the part of the nutty professor (or, to be more exact, a boffin—the term coined in World War II Britain for backroom geniuses who came up with winning inventions like radar and code-busting computers, precursors of the Silicon Valley nerds). Granted, he has a gray beard, but then so do I. He speaks with the clarity and ease of someone who has spent years teaching the aeronautical sciences—and, as soon becomes apparent, of someone urgently proclaiming how badly the planet is hurting as a result of our abuse; that mankind's desire to enjoy air travel is far from being sated; and that everybody involved in the airline business had better pledge themselves to cleaning up the skies before politicians say enough and impose curbs on air travel.

"On a global basis, aviation amounts to two percent of all man-made carbon dioxide," he tells me. "People say, hold on, if aviation is allowed to grow while everything else is pulled back, then it becomes the world's greatest CO2 producer." He articulates a more vivid picture of the problem than I've yet heard—of the immutability of carbon dioxide emissions: "Sitting here as we are, the carbon dioxide that was produced by every fire that was ever lit in the Industrial Revolution is still here, part of a growing mountain. If we stopped tomorrow, we'd still have the pile we created."

And then he gets to the flying machine. "What you want is a very efficient transporter. You've got to do everything to reduce emissions…everything that can contribute to that, including the existing architecture of the airliner and ask why it looks like that." Which is what he did. "The aircraft you see today were not designed for the job they do. They evolved from another requirement," he explains, pointing out that the grandfather of all modern jets was actually a nuclear bomber. And, he adds, "if you started over to find the ideal form for the environment, you would probably start with the blended wing."

On the face of it, the blended wing would seem to be a panacea: An airliner developed from the X-48B could produce a whopping increase in fuel efficiency of 30 percent. There are, however, two problems. If aviation grows at a rate of 5 percent a year, that 30 percent gain would be quickly eroded. Second, you would not be sitting in anything resembling the cabin of today.

I point out that some of the more hard-nosed Boeing people don't think airlines would buy into an idea as extreme as the blended wing, with its windowless cabin, but Poll points out that passengers these days are more inclined to be watching movies, playing video games, working at laptops, or listening to music than looking out windows—implying that the theater model is more apt than the tube. Given the grip that the familiar always holds on us, it would certainly call for a big adjustment of expectation and attitude. It seems to me, though, that—considering what's at stake—if the environmental gains are this substantial, passengers ought to be as prepared for big changes in the look of an airplane cabin (with no sacrifice in creature comforts) as plane makers should be to make them, and the airlines to accept them.