The Fast, Cheap and Scary Way to Cool the Planet
Blocking sunlight with technology is feasible—it's only a matter of time until someone tries it.
Congratulations. You’ve done everything humanly possible to cut carbon dioxide—to zero. But what if even that won’t be enough?
It’s one of the most uncomfortable realizations in climate research. Inertia in the climate system implies that even if emissions stopped, temperatures and especially sea levels would continue to rise for a long time. The logical conclusion leads almost immediately to the specter of solar geoengineering, an attempt to use technology to reflect a portion of sunlight back into space. The principle behind solar geoengineering is simple enough. With less sunshine coming through the atmosphere, the planet would invariably cool—and fast. At least temporarily. There’s even a natural analogue: the eruption of Mount Pinatubo in the Philippines. In June 1992—ironically, the same time as the pivotal Rio de Janeiro Earth Summit—global average temperatures were about 0.5C cooler than they would have been without all the ash and sulfur dioxide, SO₂, catapulted into the lower stratosphere by the volcano a year prior.