Though I tremble to do it, I have to agree with John Tierney, in a qualified fashion, contra Mark Kleiman:

1. The point of environmental management isn't to denounce sin, it's to get prices right. The problem with GHG-emitting activities is that they are artificially underpriced due to the lack of a carbon tax (or equivalent mechanism, such as cap-and-trade, for internalizing the external costs of those activities). With the right prices, the cost of conferences with physical attendance will rise, improving the competitive position of alternatives such as high-quality teleconferencing, which allows people to meet virtually rather than physically. But if people want or need to confer in person, and are willing to pay the full price including the price of the environmental damage their travel does, they can do so with a clear conscience.

2. Rich people use more goods and services than poor people. That's what "rich" means. Of course multi-millionaires have larger gross GHG footprints than you and I do. So what? If Tierney wants to work on decreasing income gradients, I'm all for it. But of course he's not. He just hates the idea that some rich people use their wealth to promote ideas he dislikes.

3. A large gross carbon footprint doesn't imply a large net carbon footprint. That's what offsets are about. Once GHG contributions are priced appropriately, there won't be any need for private offset purchases. But in the meantime someone who wants to be personally GHG-neutral can get there by writing checks for the activities necessary to offset his or her footprint.

1. We don't have an accurate price. We don't know how much the planet will warm. We don't know how much economic damage this will cause, or upon whom it will fall. We have not settled upon a way to price the interests of future generations in a cooler climate and a ready supply of fossil fuels. We have not even established an irrefutable argument for our status quo bias.

We will almost certainly establish the "correct" price by observation: does it make people do a lot less flying, driving, and power consumption? It therefore seems reasonable to me to evaluate whether your attendance at a conference actually leads to less flying, driving, and power consumption. An academic or journalist who flies for work five or six times a year spews more carbon than an SUV loving Texan who vacations at Grandma's.

2. Many wealthy environmentalists emit not merely much carbon, but tons of moral outrage. If they moralize about other peoples' cars, other people are entitled to moralize about their private jets.

3. Offsets are not the moral equivalent of indulgences--but they are just about as effective. I have no doubt that many who use them devoutly believe that they work, but I don't think many of them care to investigate the matter too closely. In some sense it's a technical question, but as far as I can tell, that technical question is not solveable.

Tree planting is risible unless you commit to keep the land planted forever. Shutting down third world pollution creates a rich market in polluting factories, and also does a lot of things that would have been done anyway. Other projects are even more questionable. None of them, as far as I can tell, attempt to account for rebound effects. I'm open to being convinced otherwise, but as far as I can see any cap and trade system that isn't global, and/or includes offsets, will do (to a first approximation) basically nothing to halt global warming.

I'm not saying this makes them wrong about climate change: hypocrites can speak the truth as easily as the virtuous. But I do think that if you are deeply committed to combatting climate change, you have to actually do your best to reduce your carbon footprint, not attempt to offset it. No one in Mark's or my demographic wants to hear this, because we like flying places, and we get to do a lot of it for work. No criticism of Mark implied--I'm just as guilty, or not. But we shouldn't get mad at Tierney for pointing it out, whatever his motives.