I used to try to explain all this to Tom. He was ten years old when Amin was assassinated; he remembers that trauma even if the greater geopolitical transformations passed him by at the time.

I thought he would want to know about the lost freedoms of the automobile age, a time when you could go where you wanted as fast as you wanted. It had been part of our birthright, we thought. I still remember how proud I was of my first car, a beat-up 2010 Ford, which I used to polish until it shone in the Florida sun. I missed driving — not just the freedom of it, but driving itself, a social interaction of a unique kind you got as you wrestled your way through heavy traffic on a Friday rush hour. Vanished skills, abandoned pleasures.

But Tom would stare at images of the vast streams of traffic that had flowed along the abandoned roads only a few years before, and at the poison that spread out from those crawling rivers of red lights and shining metal, blackening the land and turning the air over the cities the color of a Martian sky. And he would flick on links to accident statistics: how many died every year? No dream of freedom could possibly have seemed worth the price to Tom, who had never owned his own car, and never would.

I only saw one private car during that ride to the airport. I recognized the model. It was one of the new Jeeps, with six tires as tall as I am and a slick waterproof underside, and a little chimney stack from which it would vent its harmless hydrogen-fuel exhaust, water laced with a few exotic hydrocarbon by-products. Its cabin was perched on top of its body, a bright glass bubble. Some of these models had seats that turned into bunks, and little kitchens and toilets, and windows you could opaque to a silvery blankness. You could live in there. I felt an unwelcome stab of envy.

Its driver must have been seventy at least. Perhaps when the final generation of driver-nostalgics died off, I thought, so would the very last of the private cars. In the meantime, that guy was no doubt paying plenty for his fix.

But I still miss that old Ford of mine.

At the airport the check-in process was thorough, with cheek-swab DNA verification tests, neurological scans, and full-body imaging to make sure I wasn’t carrying a pathogen in my bloodstream or a knife in a hollowed-out rib.

I finally got on the plane. The cabin was wide-bodied and fitted out with big fake-leather couches, around which people fussed and planted their in-flight stuff. There were no windows, but every wall surface was smart, although for now tuned to a drab wallpaper. It was like a lounge in some slightly cramped hotel; only the cabin’s inevitable tubular architecture gave away the fact that we were on board a plane. My couch was smart, too. As I sat down I felt pads move silently into place, fitting my body shape and supporting my back and neck and lumbar region. All very civilized, though that cheap-hotel feeling deepened. I settled in and spread my softscreen over my lap.

The plane filled up quickly. The couches were not set in rows but in subtly randomized patterns, so you had at least the illusion of privacy. But still my neighbor, as he settled in, felt like he crowded into my space.

He was maybe forty, a round-faced man sweating so heavily his thinning hair was plastered to his scalp. His belly strained at his shirt. At one time you wouldn’t have glanced at him twice, but in these days when everybody walked everywhere he was bigger than most. He had a lot of stuff, a pack he crammed under his seat, another he shoved into the locker in front of him, and he spread out a softscreen and a pile of papers on his lap.

He caught me watching him. He stuck out his hand. “Sorry to disturb you. The name’s Jack Joy. Call me Jack.”

I shook his hand, powerful but hot and moist, and introduced myself.

He snapped his fingers to summon the steward — a human, a retro symbol of a vanished age. Jack requested a bourbon, and asked if I wanted the same; a bit uncertainly, but feeling crowded by this guy, I agreed.

Slightly breathless, he gestured at the heap of material on his lap. “Look at this crap. Every trip’s the same.” He winked. “But it costs so much to travel nowadays you have to make it worthwhile, even if somebody else is paying, right?” His accent was strong New York.

“I guess so.”

“You fly a lot?”

“I flew out here, to Florida. Otherwise, not for years.”

“It isn’t the unalloyed delight it once was. Watch this.” Without warning he slammed his fist against the fake leather armrest of his seat, making me jump. Immediately a metal band slid out of nowhere and snapped over his arm, and a blue light flashed over his head.

A stewardess came running, fingering the weapon in her holster.

Jack apologized, waving his other hand in the air, sloshing his drink. “Sorry, sorry. A nervous twitch! It always happens to me. What can I say?”

He had to submit to a scan from a handheld sensor. But eventually the stewardess spoke into a lapel mike, and with some reluctance, I thought, caused the restraint to release him and slide back into the body of his seat.

Jack turned to me. “You see that? By the time you get on the plane you’ve been through all the checks and the psycho profiling and all the rest, and you’re in your damn seat, and you think they’ll trust you at last. But no, no. One false move and wham, you’re pinned like a lab rat. I mean, what could you do? Scratch somebody’s eyes out? Lethe, even this shot glass is unbreakable. If I throw it against the wall—” He raised his arm.

“Don’t bother,” I said quickly, “I believe you.”

He laughed and sipped his drink. “It’s the way of the world, Mike — can I call you Mike?”

“Michael.”

“The way of the world, Mike. Lethe, it’s the way of the world.” He settled back on his couch with a grunting sigh, and kicked his shoes off, which did nothing to improve my immediate environment.

Lethe. I’d heard that word used as an oath before, somewhere. John, I thought; John used it sometimes.

That stewardess came by again, checking we were ready for lift-off. She caught my eye sympathetically. You want more privacy? I shrugged, subtly.

The plane surged forward and I was pressed back in my couch; I felt it adjust to accommodate me. I hadn’t even heard the engines start up. With a word I turned my smart wall into a window, and watched the drowned Florida landscape recede beneath me, covered in pools and lakes that shone in the sun like splashes of molten glass.

Once we had settled into the flight I buried myself in a softscreen study of climate change at the poles. It was a dull classroom subject, but after Tom, suddenly it was personal.

It all started with the Warming, of course; all the searches I set off looped back to that. For decades carbon dioxide had been accumulating in the air twice as fast as natural processes could remove it. By 2047 its concentration was higher than at any time in the last twenty million years, an astounding thought. The consequences were depressingly familiar. The ice was melting, the seas rising, ecosystems unraveling. All that heat energy pumped into the air and oceans had to go somewhere, so there were many more hurricanes and storms, floods and droughts than there used to be.

And so on. I skimmed all this, trying to find out about the Arctic.

At the poles the Warming is amplified, it seems. Apparently there is a positive feedback effect; as the ice melts the albedo of the ground is lowered — it reflects back less sunlight — and so the ground and the ocean just soak up more heat. As a result temperatures there have been, at times, rising ten times as fast as in the rest of the world. In the north, the ice was all gone, and strange storm systems came spinning down from that rotating plate of ocean to ravage the land. Once the sea ice actually protected the land from ocean storms and the worst ravages of the waves. Now, all around the Arctic Ocean, coastal erosion was “rapid,” “dramatic,” “traumatic,” so I read. At the same time the permafrost, the deep-buried ice cap, was melting. I’d seen some of this in Siberia; on a ground that undulated like the surface of the sea, roads collapsed, buildings just sank into the ground, and trees all over the immense, world-embracing taiga forests tipped over.