When the second Martian revolution began, Nadia was in the upper canyon of Shalbatana Vallis, north of Marineris. In a sense one could say that she started it.

She had left South Fossa temporarily to oversee the Shalbatana closure, which was similar to those over Nirgal Vallis and the east Hellas valleys: a long tent roof over a temperate ecology, with a stream running down the canyon floor, in this case supplied by pumping from the Lewis aquifer, 170 kilometers to the south. Shalbatana was a long series of lazy S’s, so that the valley floor looked very picturesque, but the construction of the roof had been complicated.

Nevertheless Nadia had directed the project with only one small part of her attention, the rest being focused on the cascading developments on Earth. She was in daily communication with her group in South Fossa, and with Art and Nirgal in Burroughs, and they kept her informed of all the latest news. She was particularly interested in the activities of the World Court, which was trying to establish itself as an arbitrator in the growing conflict of the Subarashii metanats and the Group of Eleven against Praxis, Switzerland, and the developing China-India alliance— trying to function, as Art had put it, “as a sort of world court.” That effort had looked doomed when the fundamentalist riots began and the metanats prepared to defend themselves; and Nadia had concluded unhappily that things on Earth were about to spiral down into chaos again.

But all these crises were immediately cast into insignificance when Sax called to tell her of the collapse of the West Antarctic ice sheet. She had taken his call at her desk in one of the construction trailers, and now she stared at his little face on the screen. “What do you mean, collapsed?”

“It’s lifted off the bedrock. There’s a volcano erupting. It’s being broken up by ocean currents.”

The video image he was sending cut to Punta Arena, a Chilean harbor town with its docks gone and its streets awash; then it cut again to Port Elizabeth in Azania, where the situation was much the same.

“How fast is it?” Nadia said. “Is it a tidal wave?”

“No. More like a very high tide. That will never go away.”

“So enough time to evacuate,” Nadia said, “but not enough time to build anything. And you say six meters!”

“But only over the next few . . . no one is sure how long. I’ve seen estimates that as much as a quarter of the Terran population will be— affected.”

“I believe it. Oh, Sax . . .”