SULFUROUS SOLUTION?: Climate scientists urge for research into geoengineering schemes, like injecting sulfur into the atmosphere, to thwart climate change.
ISTOCKPHOTO/ZVOZDOCHKA

Failure to make difficult choices to cut greenhouse gas emissions exposes humanity to an increasingly dire set of climate scenarios. But there is a way to buy time: Geoengineering.

The idea of tinkering with planetary controls is not for the faint of heart. Even advocates acknowledge that any attempt to set the Earth's thermostat is full of hubris and laden with risk.

Some ideas are the stuff of science fiction: 15 trillion mirrors positioned in orbit to shield the planet from the sun's rays; a fleet of blimps 20 kilometers up feeding a constant stream of sulfur into the stratosphere; a navy of robot-controlled ships prowling the world's oceans, spraying seawater skyward to generate reflective clouds.

Others are more mundane: Plant trees to soak up carbon dioxide or paint roofs white to reflect sunlight. Most are unproven. All have major drawbacks. None offset ocean acidification.

But the concept is gaining more traction as politicians, confronted with the ugly reality of trying to wean economies off fossil fuels, cast about for a strategy that will work if climate changes quickly or in nasty ways.

"Most analysts who examined the options closely had concluded that it would be reckless to mess with the planet," said David Victor, a professor of international relations at the University of California, San Diego, who specializes in energy and climate policy. "That is changing."

It's changing, in large part, because the chances of any sort of international agreement on radical emissions cuts are plummeting even as scientists find evidence that these emissions have the potential to destabilize the Earth's climate to a degree unforeseen in human history.

If those predictions come true, scientists fear any hand-wringing over the consequences of planet-wide mitigation will pale in comparison to the inconsolable pleas of populations facing rising seas, searing dust storms and savage famines, scientists warn. The world needs to know of geoengineering's pitfalls before desperate leaders turn to an untested technology.

Practical applications date to the Cold War, when both Russian and American military started seeding clouds in an attempt to induce rain. When President Lyndon Johnson was briefed about the dire effects of global warming, geoengineering was the only solution prescribed by his scientific advisors.

For years, however, it was taboo - on the fear that, if climate control was seen as a viable option, pressure on world leaders to reduce emissions might ease.

That changed in 2006 with the publication of a seminal essay in the journal Climatic Change by Nobel laureate Paul Crutzen, emeritus professor at the Institute for Marine and Atmospheric Systems at Utrecht University in the Netherlands.

Emissions cuts are the first priority, Crutzen repeated throughout his eight-page essay. But given climate change's catastrophic implications for ecosystems - and the "grossly disappointing" international political response to necessary emissions cuts - geoengineering must be explored as a potential escape route.

"Its possibility should not be used to justify inadequate climate policies," he wrote, "but merely to create a possibility to combat potentially drastic climate heating."

Crutzen and other climate scientists draw a bright bold line between the need to undertake geoengineering research and the decision to engage in actual geoengineering.