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During a year marked by startlingly unsettled weather, the world's leaders - preoccupied as they are by economic storms - have had conspicuously little to say about global warming. Indeed, when the Kyoto Protocol, once touted as the big climate fix, expires next year, will anyone notice?

In the absence of meaningful international progress on a workable emissions-reduction strategy, some climate experts have begun to ponder more radical Plan B solutions designed to prevent a torrid future filled with fierce hurricanes, vanishing glaciers and flooded lowlands.

These "geo-engineering" technologies (see sidebar), some seemingly plucked from the realm of science fiction, propose techniques to artificially reduce global temperatures and soak up excess carbon as an alternative to traditional fixes, such as green power and energy-efficient buildings. The proposals run the gamut from whitening clouds to capturing airborne carbon and deploying vast quantities of reflective materials into the orbit around Earth to deflect incoming solar rays.

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About 60 scientists and international relations experts gathered this week in Lima to contemplate the rapidly growing body of geo-engineering science and, in effect, consider a once-unthinkable question: Should the United Nations Framework Convention on Climate Change, which oversees Kyoto (and its eventual successor), seriously consider geo-engineering as part of its arsenal for fighting global warming?

The meeting in Lima is an indication that the science of geo-engineering is gaining a new aura of legitimacy on the world stage, even though few would dispute that it represents a drastic response to arresting climate change. Not only is it rife with complicated legal and ethical questions, there is also the terrifying prospect of what could happen if one of these global-scale interventions fails or has unforeseen consequences.

Indeed, many environmentalists and social justice groups are dead set against costly technical schemes to manipulate global temperatures and the atmosphere.

But the bracing question geo-engineering proponents pose is a valid one: What's the alternative, given the lack of progress with conventional fixes?

Jason Blackstock, a senior fellow at the Centre for International Governance Innovation in Waterloo, Ont., and a member of the steering committee that organized the meeting in Lima, frames the emerging debate in terms of "risk versus risk." With emissions at record levels and little hope of co-ordinated international mitigation efforts, the perils of inaction are equally troublesome, he says. "I don't think it's reasonable right now to take any option off the table."

This week certainly wasn't the first time experts have gathered to debate these almost unimaginably grandiose proposals, some of which could take decades or even centuries to deliver results. The British Parliament held extensive hearings in 2009 and the signatories of the Convention on Biological Diversity last fall hashed out a toughly worded resolution banning commercial ocean fertilization, a form of geo-engineering meant to sequester carbon by artificially promoting algae growth. Networks of geo-engineering experts have also formed to hash out voluntary research protocols and approaches for regulating these systems.

This week's session was different, however. Hosted by the UN-chartered Intergovernmental Panel on Climate Change (IPCC), the meeting marked the first time the Nobel Prize-winning organization has turned its scholarly attention to a set of ideas many critics dismiss as fanciful, and possibly destructive.

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In response, Montreal-based ETC Group, a social justice non-governmental organization that has focused intensively on geo-engineering, predicted that the IPCC will "squander its credibility" by evaluating technologies that aspire to re-engineer Earth's climate.

And some environmentalists argue that such schemes represent a distraction from the pressing business of emissions reduction. Even geo-engineering experts acknowledge that no one really understands the full ecological impact of large-scale interventions in the global climate system.

A detailed overview by Britain's Royal Society in 2009 noted that techniques such as cloud whitening and aerosol reflectors could alter local climate conditions and even damage the ozone layer. Other technologies would involve enormous amounts of mining activity or could pose risks to global food crops.

The IPCC plans to assess geo-engineering as part of its next evaluation of climate science and mitigation technology, says the Carnegie Institution's Chris Field, a global ecologist who co-chairs the panel's Working Group II. The IPCC will release its next set of climate change assessments in 2013-14; those intensely scrutinized reports inform global-climate negotiations.

Proposals for engineering Earth's climate have been circulating for decades, and some trace their origins to military applications as scientists toyed with methods to alter weather patterns for tactical reasons. Indeed, in the wake of top-secret attempts by the U.S. military to use cloud seeding in the Vietnam war, the international community negotiated a global treaty to ban such activity.

Long relegated to the margins of climate science, geo-engineering has enjoyed a kind of second life since 2005, when Paul Crutzen, a Nobel Prize-winning Dutch scientist, called for more research into global-temperature manipulation techniques as a kind of backup to chronically stalled climate negotiations.

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A rapidly growing number of scientists and international relations experts have picked up Prof. Crutzen's call to arms. "The increase in scientific papers in the last couple of years has been very fast," Mr. Blackstock says.

The tricky question now is how to conduct experiments to see if the nascent geo-engineering technologies actually work. After all, there's only one Earth, and humans have already done a lot to mess up the climate system.

The scholarly work on geo-engineering to date has been largely theoretical, with scientists modelling different solutions using climate and atmospheric data. But in recent years, a handful of privately financed ocean fertilization research projects generated international controversy as critics questioned why for-profit entities should be allowed to gamble with sensitive marine ecosystems.

For that reason, the participants at the Lima meeting included environmentalists and international-relations experts who want to ensure that the emerging research activity surrounding geo-engineering is accountable to some kind of international governance body.

"We see geo-engineering as not just a climate issue, but an emerging international relations issue," says Arunabha Ghosh, chief executive officer of India's Council on Energy, Environment and Water. His goal: push the IPCC to think about ethical and legal questions, such as what would happen if one country chose to unilaterally deploy a geo-engineering system without consulting its neighbours.

Mr. Blackstock offers another scenario: What happens if the island nations in the Pacific find themselves facing catastrophic flooding due to rising sea levels associated with global warming? Does the international community have an obligation to protect those vulnerable populations, even if it means relying on extreme technologies? "It's definitely a question we need to ask," he says.

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Clarisse Kehler Siebert, a Canadian research fellow at the Stockholm Environment Institute who attended the session, adds that environmental and civil-society groups must engage in such debates so the discussion about the regulation of research isn't dominated by scientists and technical considerations. "Geo-engineering is here, it's on the table. Banning big powerful things doesn't work. [Like nuclear weapons] it needs to be governed within a transparent framework."


Geo-engineering approaches fall into two broad categories: carbon-dioxide removal (CDR) techniques and solar-radiation management (SRM).

A detailed overview prepared in 2009 by Britain's Royal Society describes CDR as "large-scale engineering approaches which use either chemical or physical processes to remove the greenhouse gas, and biologically based methods which aim to simulate or enhance natural carbon storage processes." Time frame: decades or even centuries.

SRM describes futuristic technologies intended to reflect the sun's rays and lower temperatures, even as emissions continue to build. Time frame: years, once the technologies are deployed.

Carbon-dioxide removal

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Biomass-related methods and biochar: The combustion of crops as fuel prevents the release of carbon stored in fossil fuels. Other variations include the burial of waste wood, agricultural matter and charcoal to sequester carbon.

Verdict: It would be moderately effective and affordable, but slow, with a high potential to interfere with the global food system.

Ocean fertilization: The oceans absorb atmospheric carbon, and the resulting acidification has threatened marine ecosystems. Fertilization proposes the use of agents such as iron filings, nitrogen or phosphorous to promote the growth of algae, which absorb carbon. The algae sink, with the carbon sequestered in the depths.

Verdict: The impact on the ocean environment is highly unpredictable. Also it is seen to be slow and costly. It can at best play a "moderate role in carbon sequestration."

Chemical air capture with carbon removal: Some scientists have been developing prototype devices that soak up ambient airborne carbon and fix it in various chemical or mineral compounds, which must then be transported and stored.

Verdict: It is seen to have lots of potential, but storage venues for the captured carbon must be identified. It's slow and expensive, but low-risk.

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Solar-radiation management

Cloud whitening: Cloud cover over the oceans can be increased by spraying tiny saltwater particles into the sky. This idea has received a lot of public attention and doesn't depend on sci-fi technology.

Verdict: Cloud-whitening efforts, carried out by special flotillas, can be turned off quickly in case of problems. The impact on marine ecosystems is not known.

Increasing Earth's surface reflectivity: Making Earth's surface more reflective could bring down temperatures. Measures include painting roofs, roads and other man-made surfaces white. Other ideas: large-scale desert reflectors.

Verdict: Surface whitening is straightforward, but it would take time to paint a sufficient area to achieve a result. The Royal Society estimates that all of the world's desert areas would have to be covered with reflectors to achieve a meaningful effect.

Stratospheric aerosols: Inspired by cooling after the 1991 eruption of Mount Pinatubo, some experts have proposed jettisoning various aerosols into the stratosphere to replicate the impact of a major volcanic explosion.

Verdict: The quantity of aerosols needed to reduce temperatures is estimated to weigh less than a 10th of the cargo shipped by air each year. But scientists don't yet understand the impact on the ozone layer and other climatic systems.

Space-based solar reflectors: Reflective or refractive surfaces - everything from orbiting mirrors to dust particles or trillions of metallic disks - could be deployed in Earth's orbit.

Verdict: Besides the cost, technical complexity and time involved (decades to deploy), the obvious question is what happens if something goes wrong after all that stuff is sent into orbit.

Source: Royal Society

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