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.
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.
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."
A GEO-ENGINEERING PRIMER
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.
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.