Climate-change activists are blasting gonzo economist Steven Levitt — co-author of Freakonomics and, now, SuperFreakonomics — for the heresy of writing that bigger, crazier technologies may be the cheapest way to save us from global warming, with the added benefit of letting us go about our consumerist lives without a concern.

He mentions space mirrors to reflect sunlight and other concepts, but his cornerstone science project? A perforated garden hose stretching into the stratosphere that will disperse a mist of sulphur dioxide, creating a layer that will drive down surface temperatures, much as ash from volcanic eruptions blocks sunlight and cools the planet.

It would also create acid rain, but by Levitt's reasoning that may be the lesser of the environmental evils we face. Interesting reasoning, but I say it's just a Trojan horse for rampant apathy. Continue reading for my full analysis.

Define the problem, then the solution

This theory has an impressive pedigree. Levitt's original Freakonomics is an eye-opening, accessible guide to economics in our everyday lives. And I'm not an engineer, so I can't evaluate the actual technological feasibility or relative costs of these various geo-engineering ideas.

But in a recent radio interview, the error in Levitt's reasoning behind his outlandish ideas became apparent. No problem has ever been solved by changing human behavior, he said.

Really? Sorry, Dr. Levitt. I call bullshit.

The issue is — as it is with anything as huge, thorny, and cross-disciplinary as climate change— in how you describe the problem. Is it one big problem, or a confluence of a few thousand smaller ones? Because we like to think that big problems require big solutions, we're in danger of overlooking a more sophisticated analysis.

You can see this played out in our quest for greener energy. How do I replace a giant coal-fired plant with a wind farm? The wind farm needs to be huge, way bigger than the coal-fired plant. And it needs to be maintained. And wind doesn't blow all the time. So instead, let's just look at continuing to burn coal and find big new ways to handle the waste, like carbon sequestration in underground mines or pipelines. Or let's pursue useless technologies, like clean coal. That's cheaper when I add it all up, right?

What we forget what we were thinking when that 30-, 40- or 50-year-old coal-fired plant got built. We didn't set out to build a coal-fired plant; we set out to solve small problems, like how to end the hassle of using wood to heat our homes, or how to make electricity more reliable.

Sorry, behavior does change

I would counter that I've seen human behavior change in a thousand small ways over the past few years, especially where environmental concerns are involved. Let me give you an example of how small behavior changes can create real change for the environment via the art of unintended consequences: the war on plastic bags.

Identified as an environmental hazard in a lot of ways — they fill solid waste sites, they kill wildlife, they're made from expensive oil — the goal of driving down the use of plastic bags began as an exhortation from environmentalists.

That turned into action, for better or worse, from governments. Out here in San Francisco, a small fee was levied on to use plastic and forced used of paper bags. But paper was worse for the planet, people argued. And they may have been right, on that one economic decision.

But the change created awareness. And you started seeing more and more paper bags being reused. More stores handed out free sturdier reusable plastic bags, preferring to have their logo few hundred "green" bags than on a million bags that weren't.

Then the unintended consequences happened. San Francisco collects curbside compost — all of your yard trimmings and food scraps — if you separate them yourself. Paper bags were promoted as being compostable as well. And so, having paper bags lying around gave people a convenient way to schlep last week's stale pizza and apple cores down to their green bins.

The recovery rate of compostables began to rise. And at a conference here in October, the whisper around the room was about a green gold rush, about how energy companies were quietly securing the rights to 20 years worth of curbside compost from city governments, to use those compostables in making green power.

This new market for our trash may up-end the way cities pay for solid waste removal. Gone will be the costly contracts that may be slightly defrayed because the trash collectors could pull out metals and paper, to be replaced with a new energy firms that might pick everything up, sort it, recycle what you can, and turn a lot of what remains into green energy — and paying the city for the access to their trash resource.

The economic model is changing, and none of the technologies required for this are new or crazy. Now, banning plastic bags doesn't get all the credit, but it forced behavioral change that may have kicked off something much bigger.

Dr. Levitt is brilliant, and he's both right and wrong on geo-engineering.

Big ideas are always welcome, and we ought to think outside the box whenever we can. But taking a thousand small actions will work too, and may create the massive change we didn't expect.