The idea that we might be able to "geoengineer" the planet to purposefully change the climate has clearly moved from the fringes into the mainstream. Momentum has been building in recent years: an essay in an academic journal by a Nobel Prize winning scientist in 2006, articles in the Wall Street Journal and Foreign Policy, a largely private gathering of researchers at Harvard.

Recently things have really broken out. In addition to multiple articles and books in the popular media, the United Kingdom's Royal Society, the authoritative national academy of science there, issued an in-depth review of geoengineering and President Obama's science advisor, John Holdren, has repeatedly stated that geoengineering must be on the table as a possible approach to addressing climate change.

Yesterday, the House of Representatives' Committee on Science and Technology held a hearing that its chairman, Bart Gordon (D-TN), said was, "the first time that a congressional committee has undertaken a serious review of proposals for climate engineering."

Gordon was quick to say that this doesn't mean he supported geoengineering, and that the consensus at the hearing seemed to be that no one should deploy geoengineering until we've done a lot more research. But the very fact of the hearing confirmed that influential people are starting to take geoengineering very seriously. It's no longer just a subject for gee-whiz fascination, with science-fiction-like scenarios such a vast parasol launched into space to shield the earth from the sun. Now scientists are formulating detailed research plans, start-ups are inventing new geoengineering technologies, and politicians and foreign policy experts are considering what all of this might mean for international relations.

So, why the sudden enthusiasm for proposals to tinker with the climate? These ideas aren't new, but until recently they've been largely kept under wraps while attention has been focused on reducing greenhouse gas emissions. There are probably three main reasons for the change. First, some view geoengineering as a cheap way to avoid costly conversions to zero-emissions technology, a potential technological fix that could help them stave off climate legislation. With geoengineering as an option, they argue, there's less of a rush. We'll just cool the planet until we can get around to switching to cleaner forms of energy.

But this could be mind-blowingly stupid. One of the most popular geoengineering approaches--shading the earth with a haze of sulfate particles in the upper atmosphere--would very likely lead to severe droughts. There are other potential side effects, but a purposeful act that causes the failure of crops for potentially hundreds of millions or billions of people could also lead to international conflict. Even geoengineering enthusiasts have admitted there's a chance of war.

The second reason why geoengineering is getting a serious hearing is that scientists are growing increasingly concerned that, even if we commit to drastically cutting emissions, we've already waited too long. By the time we actually reduce emissions, enough greenhouse gases will have accumulated to cause serious climate disasters. We may need geoengineering, then, in addition to fast cuts in emissions.

The third reason is that geoengineering is cheap, so cheap that a wealthy individual could do it. There's growing concern that unless we develop a science-based international consensus about the real dangers of geoengineering, someone will go off and do it on their own.

These last two reasons seem to have been in the back of Gordon's head during his opening remarks. "Geoengineering carries with it a tremendous range of uncertainties, ethical and political concerns, and the potential for catastrophic environmental side-effects. But we are faced with the stark reality that the climate is changing, and the onset of impacts may outpace the world's political and economic ability to avoid them," he said. "This issue is too important for us to keep our heads in the sand. We must get ahead of geoengineering before it gets ahead of us."

Not everyone is taking things seriously though. Just before the committee got underway, the ranking Republican on the committee, Ralph Hall (Texas), turned to Gordon and asked, "You can stand a little fun about that outrageous thing we're going to talk about today?" Then, during the hearing he compared geoengineering to "flying elephants."