DisastersScientist offers better ways to engineer Earth's climate to blunt global warming

Published 8 September 2010

A Canadian scientist suggests two novel geoengineering approaches to limit the effects of climate change on Earth: “levitating:” engineered nano-particles, and the airborne release of sulphuric acid; both ideas are more refined than, and have advantages over, another geoengineering concept developed by geoengineers: mimicking volcanic eruptions by injecting massive amounts of sulphur dioxide gas into the upper atmosphere

There may be better ways to engineer the planet’s climate to prevent dangerous global warming than mimicking volcanoes, a University of Calgary climate scientist says in two new studies. “Releasing engineered nano-sized disks, or sulphuric acid in a condensable vapor above the Earth, are two novel approaches. These approaches offer advantages over simply putting sulphur dioxide gas into the atmosphere,” says David Keith, a director in the Institute for Sustainable Energy, Environment and Economy and a Schulich School of Engineering professor.

Keith, a global leader in investigating this topic, says that geoengineering, or engineering the climate on a global scale, is an imperfect science. “It cannot offset the risks that come from increased carbon dioxide in the atmosphere. If we don’t halt man-made CO2 emissions, no amount of climate engineering can eliminate the problems — massive emissions reductions are still necessary.”

Nevertheless, Keith believes that research on geoengineering technologies, their effectiveness and environmental impacts needs to be expanded. “I think the stakes are simply too high at this point to think that ignorance is a good policy.”

Keith suggests two novel geoengineering approaches — “levitating” engineered nano-particles, and the airborne release of sulphuric acid — in two studies about to be published (see references below). One study was authored by Keith alone, and the other with scientists in Canada, the United States, and Switzerland.

Scientists investigating geoengineering 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.

Keith says that sulphates are blunt instruments for climate engineering. It is very difficult to achieve the optimum distribution and size of the aerosols in the atmosphere to reflect the most solar radiation and get the maximum cooling benefit.

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

A downside of both these new ideas is they would do something that nature has never seen before. It’s easier to think of new ideas than to understand their effectiveness and environmental risks,” says Keith.

In his study — to be published in the Proceedings of the National Academy of Sciences, a top-ranked international science journal — Keith describes a new class of engineered nano-particles that might be used to offset global warming