Wuebbles next wants to simulate how the ozone layer will recover under alternate schedules for the phase-out of CFCs and their successors. "It's important for us to know just what it's going to take for ozone to recover," he says. Because the repair is liable to last decades, the simulations will need to account for climate change—both how warming impacts ozone and how ozone impacts warming.

No doubt exists that ozone and the climate interact powerfully, says Wuebbles. Antarctica would have no hole were its winters slightly balmier, he says, citing the comparative health of Earth's opposite pole as illustration. Meanwhile, as the planet's ultraviolet shield, ozone controls how much sunlight penetrates the atmosphere; and as the third most influential green-house gas after water and carbon dioxide, it regulates how much of that energy the Earth retains for warmth. Finally, the climate and ozone are connected through their interdependence on the ecology carpeting Earth's surface.

The time is ripe for learning how such interactions play out, Wuebbles says. Already NCAR scientists are fitting a stratosphere around MOZART-2's naked troposphere (the layer that holds the clouds and weather) so that the ozone layer and hole may be part of future simulations. Patten is preparing to extend the study of CFC substitutes into the unique chemical environment high above the south pole, which he will do on NCSA computers next year. And NCAR, Wuebbles team, and other collaborators are arranging a duet between MOZART and BACH—a Biosphere-Atmosphere-CHemistry model that will include ecology. Harnessed to a computer, this fused application would be the most gargantuan ever to draw the Earth—and not every student of the atmosphere will be able to run it.

Wuebbles predicts that he and his collaborators will soon be raising their hands again for supercomputing time from NCSA.