Over the last few years, intentionally manipulating Earth's climate on a planetary scale has gone from a fringe idea to a possibility debated by mainstream scientists. That's worried a lot of people, and last week the practice was informally placed off-limits by 193 nations.

The moratorium, enacted under authority of the international Convention on Biological Diversity treaty won't be legally binding for at least several more years. If it goes into effect, the United States – which has signed but not ratified the treaty – won't be bound to it. It would also allow small-scale, highly controlled research.

But even informally, the moratorium has teeth. It would make anyone who wants to try geo-engineering – feeding CO2-gobbling oceanic plankton with iron, pumping sunlight-blocking aerosols into the atmosphere, storing CO2 in underground rock deposits – an international pariah. And while research is technically possible, it would have to pass a regulatory gauntlet so challenging that it might as well be banned.

Not surprisingly, the moratorium is quite controversial. With each Russian heat wave or South Asian flood, and each finding that rising CO2 has historically triggered climate instability, the need for fixing the climate becomes more urgent. Without a profound and probably unlikely change in humanity's centuries-long reliance on burning fossil fuel, geo-engineering could represent a last-ditch chance at averting catastrophe, or at least buying a bit more time. If nothing else, geo-engineering research could help us learn more about the weather.

Supporters of a ban, however, say that climate and weather are too complex to engineer. Any intervention would have both winners and losers: What's good for China, say, might be bad for India, and vice versa. Geo-engineers could make a bad situation worse, and holding out for some nick-of-time rescue just distracts attention from hard, practical energy reforms that need to start now.

What do you think?

Image: Nattu/Flickr.

See Also:

Brandon's Twitter stream, reportorial outtakes and citizen-funded White Nose Syndrome story; Wired Science on Twitter.