He resolved to walk as far as the giant supermarket at the end of the road, and no further. Beyond lay the crusted ridge of permafrost that had built up in the warring crosswinds of the Euston Road. Passing near it always unnerved him; there were people in the ice, frost-blackened hands and faces staring out like half-uncovered statues. It wasn't right that they had been left there, but what could anyone do? After a few years the ice turned to stone, shifting and rupturing like the tectonic plates of the earth.

The Safeway car park was almost empty. The attendant's barrier was up, and from the lack of tyre tracks it looked like nothing had driven in or out for days. The long glass wall of the supermarket glittered with frost, and was covered in starburst cracks where the great weight of snow was slowly pushing it in, but at least the lights were still on inside, and that meant the store was open for business. Kallie had no money on him, but with luck there would be no staff to operate the tills. Many people continued to conduct a semblance of normal life, as if determined to prove that the British could remain polite in the direst of circumstances, but were easily turned from their daily tasks. Nothing could be relied upon any more, beyond the fact that the situation would worsen.

The only advantage of the new cold climate was that food stayed fresher. Just as well; supplies were sporadic and perverse. Trucks would deliver great quantities of razorblades or suntan lotion, but there would be no bread or meat. Sometimes fresh-looking food would prove to have been frozen for years, and was impossible to thaw.

The temperature inside the store was, oddly enough, too high. Because of the value of its vast cold storage capacity, Safeway operated on its own generator but the thermostats must have become damaged in the recent storms. To be hit by the smell of rotting meat was one final cruel consumerist joke to play on the few half-starved members of the public who still ventured through its doors.

Kallie unbuttoned his coat and fought the desire to vomit as he tried to ignore the sweet, ripe smell of putrifying vegetables. It was no use trying to refreeze food that had thawed. He would have to stick to tins again.

'Hey, Kallie.' He looked along the aisle to see an old friend of his mother's, Mrs Quintero, waving her bad hand at him. She had lost three fingers to frostbite last winter, and had not had the wounds properly dressed. The black stumps of her distended knuckles suppurated through filthy bandages. He was not surprised to see her; she lived here in the store. Besides, there were only a few people who visited the outside world with any regularity these days, and one tended to see the same faces.

'The heating came back on, Kallie, can you believe it? Seventy-two degrees! Everything's gone off. The one place it needed to be cold.'

'Hasn't the professor been able to fix it?'

'Are you kidding? He hasn't a practical bone in his body. I wish you would take a look.'

'Have there been any shipments lately?' he called back, ignoring her request. If he moved any closer she would come over and hug him, and he wanted to avoid that at all costs. He hated anyone touching him.

'I don't know. I've been staying in. My husband's been really sick.' She shoved a wedge of peroxided hair from her dark-rimmed eyes. He wondered why on earth she still bothered to wear make-up. 'You heard anything?'

It was the most common question of all. Everyone expected some kind of government-authorised announcement to be made. Crisis over, it's safe to come out, that kind of thing. But it had not happened in his lifetime, and he doubted it could ever happen, or that there was still a government that could make any sort of announcement. Things had moved too far away from the norm now. How could their former lives ever be restored?

'We've had a few people call in, but nobody with any news. Been ages since we had news. A crowd of rough kids came by this week, stole the coffee vending machine, really noisy types. Of course, you don't remember when the whole world was noisy.' She looked around, too sharp, too anxious. 'It's so quiet now. The snow deadens everything, but oh! it never used to be like this.'

'Things change,' Kallie shrugged, keen to move on.

'I used to work in an office,' she continued, desperate to be understood, 'I was good at my job, and always busy, no time to stop. And the noise! Telephones, typewriters, and buses out in the street, people calling to each other. Televisions just left on. Singing at Christmas as we left the pub. Sometimes you had to shout to be heard. Now you can almost hear yourself think. Noise was life.' She blinked and shook her head, too frightened to speak.

'I have to go, Mrs Quintero.'

'The professor's in the stockroom giving a class.' She had turned away, unwilling to share her distress. 'My two are in there with him.'

'I'll look in and say hi,' he assured her, even though he did not want to.

'There's tinned peaches in syrup on Aisle 6, and powdered eggs,' she added listlessly. 'Make sure you take some. You need to keep your strength up.'

Why? he thought. What the hell for? 'Thanks, Mrs Quintero. Take care.' He set his metal basket aside and decided to look in on the professor first. He wasn't really a professor; he just looked and sounded like everybody's idea of one. He must have been a schoolteacher at one time, because he behaved officiously and was always holding classes in the rear of the store.

The stockroom had long been cleared of produce, and folding metal chairs had been set in rows. The metal was cold to sit on, but everything wooden had long been burned. Anyone could attend the professor's lectures. Kallie was sure he would continue to make them even if no-one showed up at all. Today he was lecturing Mrs Quintero's children, and another boy he had not seen before. He stood at the back and raised his hand in silent gesture. The professor did not take kindly to being interrupted.

'Ice cores drilled from the centre of the Greenland ice-sheet should have warned us.' His dull monotone blunted the most interesting facts. The kids looked bored, and exhibited the distracted mannerisms of the unwell. 'They proved that the climate of the earth fluctuates far more than was ever previously realised. The last ice age took very little time to occur, perhaps just a decade or two, and lasted for over a hundred thousand years. Chance plays a large part in the survival temperature of our planet. In the seas of the world there are five natural pumps that drive the great currents of the oceans. The European Sub-Polar Ocean Programme found that one of these, the Odden Feature, powers a deep cold current that helps to control the circulation of the North Atlantic Ocean. It is caused by a vast tongue of ice in the Greenland Sea.'

Kallie quietly helped himself to a tray of sausage rolls Mrs Quintero had defrosted. They tasted like putty.

'Back in February 1993, Greenland's winter ice receded due to global warming, and the tongue of ice failed to form, dissolving into pancake ice.' He paused here to write the word PANCAKE on the wall with a blue crayon. One of Mrs Quintero's boys started repeating the word aloud.

'Without a pump to drive it, the Gulf Stream, one of the sea's warmest currents, stopped almost overnight. The Gulf Stream kept Britain and northern Europe warm, and now it's gone. Then, in less than a decade, the other great pumps died, transforming the weather patterns of the world in the wink of an eye. We are in uncharted territory now. The Royal Commission of Environmental Pollution's report into the flooding of Egypt and southern china -'

But the children were all saying 'Pancake, pancake,' and the professor's lesson, always the same lesson, was wasted. They were too young to understand, anyway. They would learn soon enough.