It’s an autumnal December, one month into the hibernation of lesser horseshoe bats. They would breathe just once an hour, but for the balmy air troubling their sleep. Their eyelids quiver. Ears twitch for the pacifying fizz and pat of first snow; failing that, for the thawing stalactite drip of the new season, begun already? Perhaps the cold has been and gone. Perhaps they missed it, having tucked themselves too far inside the cave’s oblivion.

Fiadh had stared out the conference window at the Pyrenees mountains, barely confectioned in snow, trying to block out her co-panellist expounding on subglacial water flows and multivalued sliding laws. We compared this rapid stream development in the Vavilov ice cap, averaging over three kilometres of movement annually, 3,000 times faster than the surrounding glacial ice, to the unprecedented acceleration observed in – Unable to enter a hibernate state, Fiadh would slip out of the conference far more easily than she will her field of research. She’ll forfeit her tenure-track position at Queen’s, as well as a decade’s worth of collaborative potential. But there were peaks beyond the window that would, with luck, be snow-blanketed, where she could benumb herself for a time. She hadn’t been skiing since her master’s in Iceland, back when glaciers had some heft to them, though slackened and fast-diminishing as the legs of a retired cyclist. Back when the archival wealth of ice was giddying. She fled the room ahead even of her own predictive computations. Before hearing her co-panellist’s devastating findings. She closed the door on partial answers to absolute questions.

Not an inch of the horizon is flat. A country not much larger than Northern Ireland’s big lake, Andorra has sixty-five mountains, all glacierless but rife with erosional features – cirques, arêtes, roches moutonnées, and no sales tax – so, fair field for a glaciology conference pre-Christmas. Now, the sky is smokily clouded and a warm Mediterranean air flows north. When they come into view, the glistening white summits are as inviting to Fiadh as a wedding cake to a blade. The lower slopes are jungled with school groups, but they’ll stick to the groomed pistes, snow-machine-pillowed. The quietest off-piste aspects farther up will be icy, shaded from the afternoon sun. Nothing Iceland’s wind-blasted volcanos hadn’t accustomed her to. She scans the shadows for a groggy throng of bats.

Garrett smells faintly of bath curtain in his rental ski gear. It wafts with his jerking motions forward and drunken slides back, skiing uphill to the first chairlift. He could be auditioning for the part of a rehabilitating crash victim. A rep from GeoScience Solutions’ Dublin office, Garrett had manned a stand at the conference, demoing models of their newest hypersensitive seismological instruments. He’d been outside smoking when he caught Fiadh fleeing. Somehow – in a method available only to men and unreproducible in a lab – he’d invited himself into her solitude. Jesus. Sly. I hadn’t thought of an afternoon sesh. And they rent gear at the lift? Fiadh had tried to threaten him off with boredom: I’ve not skied in nine years. Not since my daughter was born.

Ah, it’s like riding a bicycle. He’d pestled his fag into the ground and smiled so that smoke sluiced out between his widely gapped, blackly delineated teeth.

I know how to ski, but! It’s just rare I’m alone, I wouldn’t mind . . . Fiadh didn’t know this person! A moment’s friendliness at his trade stand earlier surely hadn’t indebted her to him. It’s a long time coming, just, the chance to go. In Belfast, there’s Black Mountain, it’s good for a sled, my wee Holly loves it, but, on skis, it’s thirty seconds and you’re down skirting traffic on the A55.

Heh. That’s class, Garrett had said, sledding with your kid. The edges of his eyes pinched, as if he were about to name his own kid, but instead he said: I’d say the lads on the Shankill have gas craic on it. Or is it not a hill? He peered up at the sky, as if God was the only one who could answer that: someone by the name of Fiadh wouldn’t have a notion.

What I meant was . . . Fiadh carried on, with less subtlety. I’d part ways once we’re up, if that’s alright.

Ah sure, look. We’ll form splinter groups. Garrett gave her a look of consternation, to plaster over the one-Ulster-jibe-too-many. I’m all done here anyway. He cocked his head to the building. I’ll get my coat. Then he glanced at Fiadh’s lanyard. I’m sorry I missed your talk, Fi-ad, since you’re clearly a genius. He meant it like a clap on the shoulder, but she felt it as a pat on the crown of her head.

Fay-yah, she’d corrected him, in her concertinaing Belfast accent; now open, now closed.

It’s Irish.

Ah yeah, he’d said. That makes two of us, so. We’ll do our best not to walk into a bar, will we?

Fiadh holds her pass to the turnstile whose arms silently open, then glances back to see that Garrett won’t make this lift, but his steady chatter hitches him to her, so she lets the chair swing emptily past. It’s like riding a bicycle, he calls out, shuffling through the queue just in time for the next lift to knock him in the back of the knees. Fiadh draws down the safety bar and Garrett’s skis windscreen-wipe as he hoists them onto the footrests. I just saw, this jacket . . . has a pocket in the wrist! Will you hold this? He hands her his sticks and goes about stuffing his lift pass into the rented jacket’s wrist-pocket. Would you look at the convenience of that! What? Fiadh observes the arm he’s thrusting out as if to milk something, and the ecstatic expression on his goggled face. (He’d forgone a helmet, claiming he hadn’t a great sense of sight or smell so being able to hear came in handy. The shop didn’t rent gloves or goggles, so he’d bought himself new ones without glancing at a price tag, orating on the duty to support local economies.) Fiadh smiles with closed lips, partly to establish quietness and partly from associative habit: skiing had once meant toothaching cold. These days are temperate enough to smile recklessly.

The lift ascends smoothly, only shimmying past support towers. The scene below them is berserk: snowboarders slicing directly down the too-mild gradient, obstacles be damned; groups huddled around instructors whose faces are puffy with hangover, their instructees in toilet-desperate squats; others aggressively snowploughing or standing still, twisted back to find the luminous X shape of a friend, poles oaring through the air. It’s the same scene on countless peaks across the Continent – even on ones so bare snow is dropped from helicopters like aid.

It’s a kick in the nuts, Garrett says, observing a parent skiing wide-stanced, a toddler between their legs. Nifty little fecks, slaloming around ya . . . doing jumps and racing their shadows, easy as you like. They’re not in their heads. They’ve no expectations. Just . . . happy to be moving on the magic carpet.

Do you have kids? Fiadh asks.

No, I don’t, no. I’d love to.

He goes quiet then. Though the comment had sounded like a set-up, he doesn’t weaken its candour with anything. The higher the lift takes them, the less apparent the chaos. Wet air freshens their cheeks as they hush up the velvety landscape, over Scots pines, firs clustered in the shade. There is enough time for the surreal privilege of the situation to decant.

I’m actually infertile.

Fiadh huffs a small laugh out her nose, then glances at him.

Yeah, he huffs back, kindly. The only infertile inch of the country. Well . . . eight, ten . . . you know, a fair few inches anyway.

Fiadh lets out a nervous laugh now, grateful for the chance to reset her expectations – or, like the kids, never to have had them in the first place.

My ex, girlfriend of nine years . . . left me over it. He gazes at his gloved hands, poles held parallel like a steering wheel. She actually, sort of, ghosted me. Went to ‘visit’ her cousin in Pasadena, and kept, just, staying longer . . . praising the weather, blaming the time difference. If I managed to get through, she’d put me on speakerphone with someone always in the background. D’you ever feel yourself being multitasked? He glances at Fiadh and his lips wrinkle tight. Feels kinda . . . violent. He straightens his posture. I’ve never in my life been afraid of myself. I’ve always been . . . conciliatory. But then? It totally and utterly destroyed me. Was in hospital and all that. I could barely form words. It was like, I felt like . . . concrete, drying. If anyone got close, I’d scream . . . just to protect them. But now, sure, I’m grand. Brilliant. They’re only pockets on my wrists, don’t you know! I’ve a girlfriend too, nearly six months. We’re going slow. I haven’t dropped the L bomb or anything. But she told me from day one she doesn’t want kids. She’s forty-four anyway. But. So. Nah, she’s the absolute business. He clicks his tongue. I’ll just have to act the seven year old myself for the minute, till it passes.

Fiadh hears herself saying the words in all honesty aloud when she had only meant to think them. Garrett latches on to their promise: if she has regrets, he doesn’t mind hearing them. She shakes her head, flustered. It’s not what he’s thinking: that kids are work, or that you give so much of yourself. No. It’s impossible: to tell a man who can’t have a child that he’s better off without one . . . so he can live without the pain of his child’s safety’s improbability; so he can give up, if needs must. Trapped sweat tickles her scalp, nauseating. Lifting her helmet to let air in, an image strikes her of Holly opening a drawer to find her mother’s mask lain there: her Brave Face, like a front page emblazoned with calls to action. Blood rages in her temples. What was all that evolution for? So that children would be good at dodging embers?

Garrett’s gaze on her is a phone, ringing. Finally, she admits that when she dropped Holly off to her father’s – who recently surfaced in their lives like a body thrown up by the sea after a localised storm; miraculously sober, sea-foam drying on his lips – he’d kept repeating the word whereabouts rather than just asking if Andorra was a city in Latvia or an African country or what. Neal only vaguely understands what I do, Fiadh tells Garrett. He asked what the conference was on, and I told him the usual – glacial melt, chronic underestimation of our general doom, and the tenure-track requirements of documenting it, in real time. The doom. There’s loads of data on the drowning part, I told him. Fiadh tongues blood blisters on the insides of her cheeks, now permanent as moles. I don’t know why I joked. But I held my hand level over Holly, as if to measure her, and I said: We best hope she has your tall genes, Neal. She glances at the stranger beside her and lifts her chin, just as Holly had done at the doorway, for air . . . or to see the adults better. Holly looked at me as if . . . I was an ice-cream scoop tipping off its cone.

The chair lift slows. Fiadh puts on her goggles and slides her skis off the footrests. They’re approaching the lift’s end. Raising the safety bar, Garrett asks what Holly’s dad made of all that. Would you not be worried he’d get a lawyer?

Fiadh sounds out a deadpan Ha! and shifts her bum to the edge, ready to ski down the off-ramp. She raises her voice over the reggaeton pumping onto the deck of a lift-side restaurant, where the injured and the tired and the functioning alcoholics sink their faces into huge sudsy beers, having called it a day. Already scanning for the route to the next lift that will take her closer to magnet-silver altitudes, Fiadh shouts: With Holly stood between us – our daughter who can explain the slowing of the Gulf Stream – Neal asked me, dead serious: So you think the Venice thing is part of something bigger?

They were quiet on the second lift, as Garrett had to get an email off lest phone reception cut out. He only paused to look up and say – What’s above the hill? Another hill! – and to ask if the conference was any use to her. Fiadh said that she was leaving her field of research, so not really, no. But that someone from the Swiss Federal Institute had phoned her to sound her out about contracting work, adapting her neural network approach to develop algorithms for military detection systems. There were many avenues of doom she could help chart.