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The World : CHANGING CLIMATE, CHANGING LIVES : In case of environmental panic, read this : Amid dire warnings about global warming, some odd ideas are in the mix -- such as fake trees that devour CO2.

Changing Climate, Changing Lives / One in a series of occasional articles about the effects of climate change on people's lives around the world.

November 15, 2009|Henry Chu

LONDON — If there were some kind of panic button to stop global warming, what would it look like?

How about billions of tiny mirrors, launched into orbit to deflect solar rays away from Earth? Or big, fluffy clouds, artificially whitened so they reflect more sunlight back into space? Or maybe mechanical trees, ugly but effective at sucking carbon dioxide from the air along busy highways?

Outlandish as some of these proposals may seem, scientists and engineers are paying increasing attention to such ideas amid mounting evidence that human-caused climate change is wreaking havoc in some parts of the world.

The proposals belong to a field known as geo-engineering, or manipulation of the environment on a grand scale.

As a solution to global warming, it remains a highly controversial concept, dismissed as a dangerous distraction by critics or embraced as a quick, if temporary, fix by enthusiasts such as the authors of the bestselling book "Freakonomics."

Regardless, decision-makers are beginning to take notice. The U.S. House Committee on Science and Technology held its first hearing on the topic this month.

"It's too soon to think about actually doing any of these things, but it's the right time for some serious research and for some funding from the government," said John Shepherd, a professor of Earth science at the University of Southampton in southern England, who testified at the hearing.

Shepherd is a member of the prestigious Royal Society, a fellowship of scientists that released a highly publicized report in September identifying various geo-engineering solutions and assessing their feasibility.

The ideas usually fall into either of two categories. In one, the goal is to decrease the amount of sunshine hitting and warming Earth -- one eye-popping proposal calls for unfurling a space-based gigantic shade made of a super-thin mesh of aluminum threads. A more reasonable and promising alternative, according to the Royal Society, would be to spray sulfate aerosols into clouds to make them brighter, whiter and therefore more reflective.

The other type of idea calls for removing carbon dioxide already in the atmosphere, whether by trapping and storing it via artificial trees or converting it to something else -- for example, tapping the ability of the oceans' algae to convert CO2 into oxygen through photosynthesis.

In general, the "solar radiation management" techniques would offer quick, emergency relief from rising temperatures, a dose of cosmic aspirin to bring down Earth's fever. The carbon-capture methods, though taking longer to be effective, would get at the cause of the infection.

But Shepherd, along with virtually all scientists, engineers and other experts here, emphasizes that none of these solutions is a substitute for the paramount task of getting people, and countries, to slash their carbon emissions.

That's why, at next month's global summit in Denmark on reducing greenhouse gas emissions, he hopes that policymakers don't pay too much attention to a talk he's scheduled to give on geo-engineering ideas.

"Geo-engineering is not a magic bullet, and it's not a viable alternative to carbon reduction," Shepherd said. "I hope that this is not going to be any serious component of the discussions in Copenhagen, because it would be premature for any of it to be taken into account."

Many of the ideas are "still at the back-of-the-envelope stage," he said, and the technologies some would require are years, if not decades, away. For instance, no one knows yet how to catapult 1 million tiny mirrors into space every minute for 30 years.

Critics worry that too much focus on geo-engineering will divert attention and resources from the immediate need to reduce carbon footprints, or could cause people to become complacent.

"A lot of this is just pie-in-the-sky compared to the clear and obvious things and most cost-effective things that we can be doing straightaway," said Doug Parr, a spokesman for the environmental organization Greenpeace.

In addition to the unproven technologies, he said, there are side effects that could be just as harmful to the environment as climate change. One proposal, pouring iron into the ocean to stimulate the growth of CO2-gobbling algae, would significantly alter the marine ecosystem. Spraying aerosol into clouds would set back the healing of the ozone layer.

This raises questions of ethics and international governance. Who gets to decide which techniques are used and at what cost? What happens if a U.S.-driven solution creates new problems for people in Asia, or vice versa?

"For example, the sulfate aerosols: The consequence of that would almost certainly be to affect rainfall patterns, and when you affect rainfall patterns, there are going to be winners and losers," Parr said. "How do the losers feel about these experiments?"

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