Mirrors in space? Salty clouds? Scientists weigh drastic cures for climate change

The Canadian Press ~ The News
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MONTREAL - While world leaders gear up to discuss reducing emissions, a growing community of scientists is looking to far more drastic solutions they say could one day save the world from the impact of global warming.
The field of geoengineering has spawned a host of Earth-cooling ideas to deliberately meddle with Mother Nature and stave off the potential effects of melting permafrost and rising sea levels.
One idea being bounced around involves launching mirrors into outer space to reflect sunlight.
Another would block out solar radiation by blanketing blue skies with perpetually overcast conditions.
But tricky questions remain: Will the remedies further endanger the Earth? Will humans be tempted to use geoengineering solutions as a quick fix instead of curbing greenhouse-gas emissions?
As countries prepare for a UN climate conference in Copenhagen next month, these are some of the thorny questions about to be addressed at a much smaller gathering in Montreal.
A panel of climate-change experts will gather at McGill University on Thursday to debate the potential ethical, political, and scientific impacts of geoengineering.
"My first idea (about geoengineering) - like everybody's first idea - was that it was crazy," said David Keith, Canada Research Chair in Energy and the Environment at the University of Calgary.
"That we should put more pollution in the stratosphere to compensate for the pollution that we've already put in the rest of the atmosphere - it's just insane."
Geoengineering ideas have been around for decades, but they took off in 2006 after Nobel laureate Paul Crutzen wrote about sending sulfate aerosols into the stratosphere to block out the sun's rays.
Earlier this month, the U.S. Congress - in conjunction with the British Parliament - held its first-ever hearing on geoengineering.
When Keith, who first heard about geoengineering in 1989, took a closer look at some of the ideas, he realized that humans have the capacity to manage some of the "very real" climate threats.
"The central reason why we need (geoengineering) is the risks of climate change are quite uncertain," said Keith, who has served on advisory panels for the U.K.'s Royal Society geoengineering study and the Intergovernmental Panel on Climate Change.
But Keith has also long feared that geoengineering proposals could entice world leaders to abandon existing efforts against climate change.
"Of course I think it's dangerous - I think that's also a widely shared view," he said.
"But I do think that if we are serious about managing climate risk, we do need to develop - over decades, not years - the capability to do it."
In the last few years, more and more scientists have been running models on possible last-ditch options if current efforts fail.
Some believe they could also come in handy if climate change hits the planet harder than expected.
Alan Robock, a climatologist who testified this month before U.S. Congress, said humans might be able to cool the Earth by mimicking the after-effects of a volcanic eruption - either by firing particles into the stratosphere with artillery or through a 40-kilometre hose strapped to a balloon.
Another prominent proposal to manage solar radiation involves brightening clouds above the oceans by spewing salt particles into the bottom of them from ships.
But models have shown that some ideas pose major risks themselves. One suggested the Amazon forest would die from drought if clouds over the Atlantic Ocean were brighter.
Robock said that although geoengineering creates a "moral hazard," more research is necessary in case humans fail to curb emissions or adapt to rising temperatures.
"Our response should be mitigation - geoengineering will not solve the problem for us," said Robock, a climatology professor at Rutgers University.

Organizations: U.S. Congress, UN, McGill University University of Calgary British Parliament Intergovernmental Panel on Climate Change Rutgers University

Geographic location: MONTREAL, Copenhagen, U.K. Amazon forest Atlantic Ocean

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