So. High barren rocky land, dusted with snow wherever shade predominated, so that the shadows tended to be white. Little sign of life except in basins, where the ecopoets helped along their little collections. Clouds surged in from west in the winter, east in the summer. The southern hemisphere had the seasons reinforced by the perihelion-aphelion cycle, so that they really meant something. On Tyrrhena the winters were hard.

Nirgal wandered the basin after storms, looking to see what had blown in. Usually it was only a load of icy dust, but once he found an unplanted clutch of pale blue Jacob’s ladders, tucked between the splits in a breadloaf rock. Check the botanicals to see how it might interact with what was already there. Ten percent of introduced species survived, then ten percent of those became pests; that was invasion biology’s ten-ten rule, Yoshi said, almost the first rule of the discipline. “Ten meaning five to twenty, of course.” Once Nirgal weeded out a springtime arrival of common streetgrass, fearing it would take over everything. Same with tundra thistle. Another time a heavy dust load fell on an autumn wind. These dust storms were small compared to the old global southern-summer storms, but occasionally a hard wind would tear up the desert pavement somewhere and send the dust below flying. The atmosphere was thickening rapidly these days, fifteen millibars a year on average. Each year the winds had more force, and so thicker areas of pavement were at risk of being torn away. The dust that fell was usually a very thin layer, however, and often high in nitrates; so it was like a fertilizer, to be washed into the soil by the next rain.

Nirgal bought a position in the Sabishii construction coop he had looked into. He went in often to work on the town’s buildings. Up in the basin he did some assembly and testing of solo blimpgliders. His work cottage was a small building made of stone-stacked walls, with plates of sandstone for shingles. Between that work and the farming in the greenhouse and his potato patch, and the ecopoesis in the basin, his days were full.