Are carbon offsets like papal indulgences?

Today Ellen Goodman penned a column connecting fertility rates and women's to the environment, but it was this comment that caught my eye:

Well, I am not a fan of carbon offsets, which have been described as a get-out-of-jail-free card. I don't cotton to the idea that we can neutralize our wasteful ways by planting a tree in the rain forest. The idea that I can balance flying by preventing a few little carbon footprints smacks of an elitism I thought went out with the Raj

I've heard this sentiment before, although the comparison has usually been made to the old practice of selling indulgences.

I think the notion that a carbon offset is like "paying for a right to sin" or a "get-out-of-jail-free" misses the point entirely, and that belief can have dangerous consequences for policy discussions.

A sin is something you shouldn't do at all - that's why it's a sin (or if you prefer the get-out-of-jail analogy, something illegal is something you shouldn't do). Period. Hence an "offset" for sinful or unlawful behavior is anathema, and people like Goodman are absolutely right to view offsets such as indulgences or "get-out-of-jail" cards as a terrible thing.

But here's the key point: there is NOTHING WRONG with emitting carbon. The climate is not threatened by the emission of carbon. This is where Goodman and others get confused about offsets. The problem faced by the climate is the increase in CO2 concentration in the atmosphere. If you emit a ton of CO2 in one place and store or sequester it in another place, then you have added no net CO2 to the atmosphere, and thus truly have "offset" your "sin." Indulgences or get-out-of-jail-free-cards do not undo the harm to the world of the original sin, but carbon offsets do.

Of course, this all presumes that the offsets are real, measurable, etc. - that they truly are offsetting emissions, sequestering carbon, planting trees, etc. But there is no intrinsic reason why a carbon offset cannot truly negate the effects of one's emissions.

If we view carbon emissions as intrinsically sinful, we will not make practical progress on climate change. Not that the best offset isn't an emission reduction, but the fact is that we can reduce but not eliminate many sources of carbon emissions, and offsetting can be a practical and useful means for ensuring that those emissions that remain do not become a "sin" to the climate.