For those who didn't read Brendan's link:
It pointed out that candles most likely contribute to CO2 production moreso than burning coal. There was the counter-argument that environmentally friendly candles exist, but Coblin the Economist thinks this didn't happen. Why?
Fossil fuel based candles are cheaper than environmentally friendly candles. It's easy to flick off a switch and feel involved in an environmental revolution, but people wouldn't make the effort to buy environmentally friendly candles. People want to do it at a low cost to themselves, while feeling the benefit of the sense of pride or achievement. Just like how people will make an uninformed vote to feel they have completed their "duty," or to avoid a fine (in the case of Australia), people will make an uninformed trade-off to feel environmental. The unintended consequence (as there always is!) is that more CO2 emissions are produced.
But I always say that people are rational! Why haven't they acted so rationally now? It's because the incentives are missing, or diluted. In a typical market, people have an incentive to do well for themselves. In voting, you know (almost certainly) that your vote will not make the difference - your vote is only symbolic. There has never been a election decided by a single vote. So you make a vote to feel proud, but you certainly won't feel the need to research every candidate's policies and past voting records. Such an action simply won't bring much more benefits than the costs of seeking that information. By the same principle, the incentives are diluted for the environment, the costs of polluting are shared by the entire population. This is analogous to splitting the bill in a large dinner. You will feel less hesitant to pick the more costly dishes, because you know when it comes to splitting the bill, the costs are shared and you've only paid for one sixteenth of your lobster.
People won't mind participating in a show of hands for their support for environmentalism, but they don't want it if it comes at a high cost (whether it be time, effort or money). Sometimes this kind of rational stupidity can cost.