Mt. Pinatubo is an active volcano in the Philippine's frequently studied by scientists. (U.S. Geological Survey)
Releasing engineered nano-sized disks or sulphuric acid, a condensable vapour, above the Earth are two novel approaches that offer advantages over simply putting sulphur dioxide gas into the atmosphere, says Dr. David Keith, a University of Calgary climate scientist.

Scientists investigating geoengineering, or engineering the climate on a global scale, have so far looked mainly at injecting sulphur dioxide into the upper atmosphere. This approach imitates the way volcanoes create sulphuric acid aerosols, or sulphates, that will reflect solar radiation back into space—thereby cooling the planet’s surface.

One advantage of using sulphates is that scientists have some understanding of their effects in the atmosphere because of emissions from volcanoes such as Mt. Pinatubo, Keith says.

Geoengineering “is inherently imperfect,” says Keith. “It cannot offset the risks that come from increased carbon dioxide in the atmosphere,” he says. “If we don’t halt man-made CO2 emissions, no amount of climate engineering can eliminate the problems—massive emissions reductions are still necessary.”

Keith suggests two novel geoengineering approaches - ‘levitating’ engineered nano-particles and the airborne release of sulphuric acid. The new class of engineered nano-particles that might be used to offset global warming more efficiently and with fewer negative side-effects than using sulphates.

Releasing sulphuric acid, or another condensable vapour, from aircraft would give better control of particle size, thereby reflecting more solar radiation back into space while using fewer particles overall and reducing unwanted heating in the lower stratosphere.

(University of Calgary)