“Sort of. They tend to cancel each other out. There are a lot of Red projects, you know, to protect the higher altitudes, and any place they can in the south. They’ve got that constitutional height limit to back them, and so they’re always taking their complaints right up to the global court. They win there, and do their thing, and then all the little development projects are somewhat counterbalanced. It’s a nightmare legally.”

“But they’re managing to hold things steady.”

“Well, I think the high altitudes are getting a bit more air and water than they’re supposed to. You have to go really high to get away from it.”

“I thought you said they were winning in court?”

“In the courts, yes. In the atmosphere, no. There’s too much going on.”

“You’d think they’d sue the greenhouse-gas factories.”

“They have. But they’ve lost. Those gases have everyone else’s support. Without them we’d have gone into an ice age and stayed there.”

“But a reduction in emission levels. . . .”

“Yeah, I know. It’s still being fought over. It’ll go on forever.”

“True.”

Meanwhile the Hellas Sea’s sea level had been agreed on; it was a legislative fact, and efforts all around the basin were coordinated to make sure the sea obeyed the law. The whole matter was fantastically complicated, although simple in principle: they measured the hydrological cycle, with all its storms and variations in rain and snow, melting and seeping into the ground, running over the surface in creeks and rivers, down into lakes and then into the Hellas Sea, there to freeze in the winter, then evaporate in the summer and begin the whole round again . . . and to this immense cycle they did what was necessary to stabilize the level of the sea, which was about the size of the Caribbean. If there was too much water and they wanted to draw down the sea level, there was the possibility of piping some of it back up into the emptied aquifers in the Amphitrites Mountains to the south. They were fairly limited in this, however, because the aquifers were composed of porous rock which tended to crush down when the water was first removed, making them difficult or impossible to refill. In fact spill-off possibilities were one of the main problems still facing the project. Keeping the balance. . . .

And this kind of effort was going on all over Mars. It was crazy. But they wanted to do it, and that was that. Diana was talking now about the efforts to keep the Argyre Basin dry, an effort in its way as large as the one to fill Hellas: they had built giant pipelines to evacuate water from Argyre to Hellas if Hellas needed water, or to river systems that led to the North Sea if it didn’t.

“What about the North Sea itself?” Maya asked.