Siobhan said, “But how much of the storm would this screen out?”

Mikhail and Toby displayed their figures. It turned out to be only a few percent.

“Enough to mitigate global warming, perhaps,” Mikhail said sadly. “But far from adequate for the problem we face now. We are going to have to take out almost all of the incoming radiation—letting even one percent through may be far too much.”

“Then we’ll have to think bigger,” Siobhan said firmly.

Toby said slyly, “Bigger it is. If you want to inject dust into the air, rather than trying to mimic a volcano—why not just set one off?”

Mikhail and Siobhan glanced at each other, startled. Then they went to work.

Coming up with such ideas was precisely why Siobhan had invited Toby to these sessions.

He had been unsure. “Siobhan, why me? I’m an events manager, for heaven’s sake! My contribution should have ended at making sure there were enough biscuits to go around.”

She had studied him with fond exasperation. He was a big, somewhat overweight, shambling man, with raggedly cut brown hair and a weak chin. He wasn’t even a scientist; he had majored in languages. He was a peculiarly English type who would always be valued by stuffy British institutions like the Royal Society, not only for his intelligence and obvious competence, but also for his comforting air of upper-middle-class safeness. But he had one typically English characteristic that she, born in Northern Ireland and so something of an outsider, didn’t value so highly, and that was an excess of self-deprecation.

“Toby, you’re not here for biscuits, appreciated though they are, but for your other career.”

He looked briefly baffled. “My books?”

“Precisely.” Toby had published a whole series of lyrically written popular histories of forgotten corners of science and technology. And that was what had prompted her to turn to him. “Toby, we’re faced by a megaproblem. But since Tsiolkovski people have been dreaming up a whole suite of more or less wacky mega-engineering possibilities. And that’s what I think we’re going to need to draw on now.”

There had been one group in London she was thinking of particularly, called the British Interplanetary Society. “I gave them a chapter in one of my books,” Toby had told her when she mentioned them. “The Society has been absorbed into a pan-European grouping now, and doesn’t seem to be half so much fun. But in its heyday it was a place to play for a lot of respectable scientists and engineers. They dreamed up lots of ways to bother the universe …” This sort of fringe thinking was what they needed to draw on now, she believed.

He grinned. “So I’m an ambassador from the lunatic fringe? Thanks very much.”

But Mikhail had said, “We must consider ways to protect the whole Earth. Nobody has faced such responsibility before. I think in the circumstances a little lunacy might be just what we need!”

With some hard work on their softscreens, and frequent calls to Aristotle, they hurriedly fleshed out Toby’s volcano option. Perhaps it could be done—but it would have to be a big volcanic bang, far bigger than any in recorded history and possibly bigger than anything in the geological record. As nobody had tried such a thing before, its effects would be quite unpredictable, and possibly a remedy even worse than the problem. Siobhan stored the discussion in a file in Aristotle’s capacious memory that she labeled “last resorts.”

They quickly rattled through some more research on so-called “intrinsic” methods of protection, things you could do within the Earth’s atmosphere, or maybe from low orbit. But they all provided inadequate screening. There was no reason why some of these methods shouldn’t be put in place. They would provide an extra few percent of cover—and would at least give the impression to the public that something was being done, a not inconsiderable political factor. But if they couldn’t dig up a way to knock out almost all of the sun’s ferocious glare, such projects would be nothing but sops, which wouldn’t make any difference to the final outcome.

“So we move on,” Siobhan said. “What next?”

Toby said, “If we can’t protect the Earth, perhaps we have to flee.”

Mikhail growled, “Where? The storm will be so intense that even Mars is not safe.”

“The outer planets, then. An ice moon of Jupiter—”

“Even at five times Earth’s distance, the reduction in intensity of the storm would not be sufficient to save us.”

“Saturn, then,” Toby pressed. “We could hide on Titan. Or a moon of Uranus, or Neptune. Or we could flee the solar system altogether.”

Siobhan said quietly, “The stars? Can we build a starship, Toby?”

“Make it a generation starship. That’s the most primitive sort: an ark, big enough to hold a few hundred people. It might take a thousand years to reach Alpha Centauri, say. But if the emigrants’ children, living and dying on the ship, could continue the mission—and then their children would do the same—eventually humans, or at least descendants of humans, would reach the stars.”

Mikhail nodded. “Another idea of Tsiolkovski’s.”

Toby said, “Actually, I think it was Bernal.”

Siobhan said, “How many people could we save that way?”

Mikhail shrugged. “A few hundred, maybe?”

“A few hundred is better than none,” Toby said grimly. “A gene pool of that size is enough to start again.”

Mikhail said, “The Adam and Eve option?”

“It’s not good enough,” Siobhan said. “We are not about to give up on saving the billions who are to be put to the torch. We have to do better, guys.”

Mikhail sighed sadly. Toby averted his eyes.

As the silence lengthened, she realized that they had nothing more to offer. She felt despair settle inside her, suffocating—despair and guilt, as if this huge catastrophe, and their inability to think their way out of it, were somehow her fault.

There was a modest cough.

Surprised, she looked up into the empty air. “Aristotle?”

“I’m sorry to break in, Siobhan. I’ve been taking the liberty of running supplementary searches of my own based on your conversation. There is an option you may have missed.”

“There is?”

Mikhail, in his softscreen image, leaned forward. “Get to the point. What do you suggest?”

“A shield,” Aristotle said.

A shield? …

Data began to download to their displays.

18: Announcement

The President of the United States took her seat behind her desk in the Oval Office.

The place was calm, for once. Just a single camera faced her, a single microphone loomed over her, and a single technician watched her. The office was equipped with only simple props: a Stars and Stripes, and a Christmas tree to mark this month of December 2037. As the tech counted her down on his fingers in the time-honored way, the President touched the simple necklace at her throat, but she resisted the temptation to adjust the black hair, now threaded with silver, that her makeup artist had spent so long sculpting.

Juanita Alvarez was the first Hispanic woman to become President of what remained overwhelmingly the most powerful single nation on the planet. With her compassion, her blunt common sense, and her obvious gut instinct for the health of a democracy, the people who had voted for her, and many who hadn’t, had taken her to their hearts.

But today she was speaking to more than just the citizens of America. Today her message, simultaneously translated by Aristotle and Thales into all the spoken, written, and gestural languages of humanity, would be broadcast by TV, radio, and webcast to three planets. Later her words and their implications would be analyzed and parsed, praised and criticized, until the last bit of sense had been wrung out of them, as none of her words had ever been examined before—and almost immediately, of course, based as much on what she had not said as on the words themselves, a legion of conspiracy theories would spring up.