 Consider the first two questions. Very often these are treated together, but they are not necessarily the same. One might think, for example, that one agent has a responsibility to mitigate (on the grounds that doing so would be an effective way of making a significant reduction of greenhouse gas emissions) but that others have a duty to bear some, or all, of the costs. In such a case, then, our answer to the Climate Action Question might be that X should mitigate, but our answer to the Burden-Sharing Question might be that Y should bear the cost involved in X’s mitigating. To illustrate: one might think that developing countries should mitigate and should use clean technology instead of fossil fuels, but one might also think that the cost of the clean technology should be shouldered by others.