“Here is the idea. Assume that, in the present day, the existing Polar Depression were flooded, with inlets to the Southern Ocean provided by cutting a canal through the Utopia region on the eastern side of Terra Grande, and by redirecting the flow of the River Lethe in the west. Assume the work could be done very rapidly, within a few years’ time.”

There was the briefest of pauses. “This would cause a Polar Sea to form,” Unit Dum went on. “However, the concept is implausible. There is no way of performing such an enormous engineering task in any practical length of time.”

“Even if we could do it, I’m sure the collateral damage to existing ecosystems and property would be huge,” said Unit Dee, clearly talking more to Unit Dum than to Kresh.

“Current projections show the issues of damage to ecosystems and property become moot in between two and two point five standard centuries,” Unit Dum replied.

“Why do they become moot?” Kresh asked, fearing the answer.

“Because,” Unit Dee replied, her voice clearly unhappy, “our current projection shows all ecosystems collapsing and all humans-the owners of the property-either dying or being evacuated from the planet by that time.”

Kresh was genuinely surprised. “I was not aware that the numbers were that bad. I thought we at least had a chance at survival.”

“Oh, yes,” said Unit Dee. “There is at least a chance human life will survive here. That is in large degree a matter of choice for your descendants. Human beings can survive on a lifeless, airless, sterile ball of rock if they choose to do so. If the city of Hades were domed over or rebuilt underground, and properly shielded, it could no doubt sustain a reduced population indefinitely after the climate collapses.”

“But things are improving”‘ Kresh protested. “We’re turning things around!”

“So you are-for the moment, in localized areas. But there is little or no doubt that the current short-term improvements cannot be sustained and extended in the longer term. There is simply not enough labor or equipment to expand the zones of improved climate far enough, and establish them firmly enough, for them to be self-sustaining.”

“And therefore there is no real point in worrying over ecological damage or property loss,” Kresh said. “Fine. Disregard those two points-or, rather, factor in the results of attempting to deal with them, of efforts to repair the damage.”

“The calculation involves a near-infinite number of variables,” said Unit Dum. “Recommend a pre screening process to select range of near best-case scenarios and eliminate obviously failed variants.”

“Approved,” Kresh said.

“Even the prescreening process will take a few minutes,” said Unit Dee. “Please stand by.”

“As if I had much choice,” Kresh said to no one in particular. He sat there, looking from Unit Dee’s smooth and perfect hemispherical enclosure to the boxy, awkward, hard-edged looking enclosure around Unit Dum. Dum’s enclosure, or containment, or whatever, at least had the merit of looking like machinery. Dum looked like it did something, was hooked into things, made things happen. It was hardware and wires. It was solid, firmly attached to reality by power cables and datastreams. Dum was of this world.

In many more senses than one, Dee plainly was not. She was sheltered from the rude outside universe. She was the smooth and perfect one, sealed off in her idealized containment enclosure that needed special treatment. Dee looked more like an abstract sculpture than a working robot. She looked liked something that was supposed to stand off, aloof, on her own, a divine being or magic totem to be consulted rather than a machine meant to do work. And was that so far off? Kresh glanced at Soggdon on the far side of the lab, pretending to be puttering around with something or other while she kept a nervous, unhappy eye on Kresh.

Yes, indeed. Unit Dee had her acolytes, her priests, who ministered to her whims and did their best to rearrange the world to suit her convenience, who walked on eggshells rather than anger or upset the divine being on whom all things depended. Kresh thought suddenly of the oracles of near-forgotten legend. They had been beings of great power-but of great caprice and trickery as well. Their predictions would always come true-but never in the way expected, and always at an unexpected price. Not a pleasant thought.

“I believe we are ready to begin with the main processing of the problem,” Dee said, her voice corning so abruptly into the silence that Kresh jumped ten centimeters in the air. “Would you care to observe our work?” she asked.

“Ah, yes, certainly,” said Kresh, having no idea what she had in mind.

The lights faded abruptly, and, flashing into being with the silence and suddenness of a far-off lightning strike, a globe of the planet Inferno appeared in the air between Kresh’ s seat at the console and the enclosures for the two control units.

The globe was a holographic image, about three meters in diameter, showing the planet’s surface with greater precision than Kresh had ever seen. Every detail was razor-sharp. Even the city of Hades was clearly visible on the shores of the Great Bay. Kresh had the feeling that if he stepped up close enough to the globe and peered intently enough, he would be able to see the individual buildings of the city.

Inferno was a study in blue ocean and brown-and-tan land, with a pathetically few dots and spots of cool and lovely green visible here and there on the immense bulk of Terra Grande. Kresh tried to tell himself that they were making progress, that it was something just that their efforts were on a large enough scale to be plainly visible from space. But he wasn’t all that convincing, even to himself. Somehow, over the last few days, it had come home to him that the great efforts they had made were as nothing, that the noble progress he had been so proud of scarcely represented forward movement.

But he did not have time to consider long. The globe turned over on its side, so that the northern polar regions were facing Kresh directly. Then, as he watched, the landscape began to change, shift, mutate. The River Lethe, a thin blue line running from the mountains west of the Great Bay, suddenly widened, and a new line of blue began to cut its way toward the Polar Depression, until the combined canal and river cut through the length of Terra Grande. Yes, Kresh could see it. Dredge the canal deep enough to allow a flow into the upper reaches of the Lethe, takes steps to make sure the channel scoured itself deeper instead of silting over, and it would work. Water would flow from the Polar Sea into the Great Bay. Assuming there was a Polar Sea, of course. At the present time, as shown in the simulation, there was nothing but dull white ice, a significant fraction of the planetary water supply locked up in the deep freeze where it could do no one any good.

But Dum and Dee were far from done with their modeling. Kresh looked to the western regions of Terra Grande. It was plain that things were not quite so simple or straightforward there. Again and again, a wedge-shaped channel of blue water appeared. The northernmost portion of its channel constantly shifted position, widened, narrowed, expanded, contracted, vanished altogether for a moment and then reappeared somewhere else. Plainly, the two control units were searching for the optimum positioning of the channel.

At long last the image settled down to a wide channel cutting straight north through the Utopia region. Kresh shook his head and swore under his breath. The optimum channel the two control units had chosen followed almost exactly the same path Lentrall had shown him. Maybe the pushy young upstart did know what he was talking about.

“Channel pattern as presented within one percent of theoretical optimum configuration,” Unit Dum announced. “That figure is well inside accumulated combined uncertainty factors of many variables.”