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This article is from the In-Depth Report Copenhagen and Climate Change

Is geoengineering humanity's last hope to avoid catastrophic global warming?

earth's atmosphereDo you really want to start messing with the atmosphere? If not, then stop emitting so much CO2. Or so argues the U.K.-based Royal Society, the same people who brought you Isaac Newton, Charles Darwin and Stephen Hawking. A new report by the Society analyzes so-called geoengineering—"the deliberate large-scale manipulation of the planetary environment," or consciously tweaking Earth's climate in an attempt to stave off global warming—and finds that it is feasible and worth studying carefully, but probably not something we want to get involved in.

Artificial volcanoes, mirrors in space or other climate-altering schemes might be the last, best hope for mankind if we don't get started reducing greenhouse gas emissions pronto—specifically a 50 percent reduction (at minimum) in global emissions from 1990 levels by mid-century, according to a 12-member panel convened by the Society. "Geoengineering and its consequences are the price we may have to pay for failure to act on climate change," said report chair and climate modeler John Shepherd of the University of Southampton in a prepared statement. "Used irresponsibly or without regard for possible side effects, geoengineering could have catastrophic consequences similar to those of climate change itself."

After a year spent examining various ideas, the Society panel split geoengineering into two camps—dubbed Carbon Dioxide Removal and Solar Radiation Management—and opted primarily for the former. Examples include artificial trees to suck CO2 out of the atmosphere or even real trees in restored forests. After all, taking CO2 out of the atmosphere is simply reversing the climate experiment we've been engaged in since, well, at least the founding of the Royal Society in 1663.

Of course, that more sensible solution is also more costly. It would be cheaper to simply go the route of managing solar radiation—for instance, by pumping sulfate and other aerosols into the atmosphere, thereby mimicking the cooling blanket of a major volcanic eruption, and keeping that up continuously until the underlying problem resolves itself, however long that might take. This approach might have a few significant side effects, potentially including, but not limited to acid rain, the elimination of the ozone layer in the stratosphere, and years without summers.

So why even consider it? "If we are confronted with a climate emergency and decide we cannot tolerate any more warming, engineering some system to deflect more sunlight back to space would likely be the primary option available to cool the Earth quickly," said report coauthor and climate scientist Ken Caldeira of the Carnegie Institution's Department of Global Ecology at Stanford University in a prepared statement. "We need to study these options now so that we can understand the pluses and minuses in case we need to deploy them."

Already marked as minuses, according to the report, are the charcoal soil amendment known as biochar, fertilizing the ocean with iron to promote plankton blooms, and schemes to make Earth more reflective by putting mirrors across deserts (or, for that matter, painting roofs white) because, in the latter case, it's just not deemed to be very effective. A similar report from the U.K.'s Institution of Mechanical Engineers, however, found a little more merit in the white roofs technique as well as the aforementioned artificial trees or carbon dioxide-sucking algae turned to biofuel.

My personal favorite is what I call the fleet of Flying Dutchmans—crewless ships spraying saltwater into the air to increase cloud cover. According to research from the University of Texas and the American Enterprise Institute, a conservative think-tank, global warming could be solved by spending a mere $9 billion on such ships.

Nevertheless, as the report states: "The safest and most predictable method of moderating climate change is to take early and effective action to reduce emissions of greenhouse gases. No geoengineering method can provide an easy or readily acceptable alternative solution to the problem of climate change." And shading the Earth one way or another from the sun would do nothing to stop climate change's other major impact: more acidic oceans.

But geoengineering is serious business. Everyone from the American Meteorological Society to Obama's science advisor John Holdren—and now the Royal Society whose motto is "Take nobody's word for it"—has endorsed further study of these seemingly mad scientist schemes because we may need them. And that's because mankind's most massive geoengineering scheme to date—climate change courtesy of greenhouse gas emissions—is already going gangbusters.

Image: Courtesy of NASA

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