This last one stopped him again. The poster was the work of the atmospheric chemist S. Simmon and some of his students, and reading it made Sax feel considerably better. When Sax had been made head of the terraforming project in 2042, he had immediately initiated the construction of factories to produce and release into the atmosphere a special greenhouse gas mix, composed mostly of carbon tetrafluoride, hexafluoroethane, and sulphur hexafluoride, along with some methane and nitrous oxide. The poster referred to this mix as the “Russell Cocktail,” which was what his Echus Overlook team had called it in the old days. The halocarbons in the cocktail were powerful greenhouse gases, and the best thing about them was that they absorbed outgoing planetary radiation at the 8- to 12-micron wavelength, the so-called “window” where neither water vapor nor CO2 had much absorptive ability. This window, when open, had allowed fantastic amounts of heat to escape back into space, and Sax had decided early on to attempt to close it, by releasing enough of the cocktail so that it would form ten or twenty parts per million of the atmosphere, following the classic early modeling on the subject by McKay et al. So from 2042 on, a major effort had been put into building automated factories, scattered all over the planet, to process the gases from local sources of carbon and sulphur and fluorite, and then release them into the atmosphere. Every year the amounts pumped out had increased, even after the twenty parts per million level had been reached, because they wanted to retain that proportion in an ever-thickening atmosphere, and also because they had to compensate for the continual high-altitude destruction of the halocarbons by UV radiation.

And as the tables in the Simmon poster made clear, the factories had continued to operate through 2061 and the decades since, keeping the levels at about twenty-six parts per million; and the poster’s conclusion was that these gases had warmed the surface by around 12°K.

Sax moved on, a little smile fixed on his face. Twelve degrees! Now that was something!— over twenty percent of all the warming they needed, and all by the early and continuous deployment of a nicely designed gas cocktail. It was elegant, it truly was. There was something so comforting about simple physics. . . .

• • •

By now it was ten A.M., and a keynote talk was beginning by H. X. Borazjani, one of the best atmospheric chemists on Mars, concerning just this matter of global warming. Borazjani was apparently going to give his calculations of the contributions of all the attempts at warming that had been made up until 2100, the year before the soletta had come into operation. After estimating individual contributions, he was going to try to judge whether there were any synergistic effects taking place. This talk was therefore one of the crucial talks of the conference, as so many other people’s work was going to be mentioned and evaluated in it.