According to the Polluter Pays Principle, excessive emitters of greenhouse gases have special obligations to remedy the problem of climate change, because they are the ones who have caused it. But what kind of problem is climate change? In this paper I argue that as a moral problem, climate change has a more complex causal structure than many proponents of the Polluter Pays Principle seem to recognize: it is a problem resulting from the interaction of anthropogenic climate effects with the (...) underlying vulnerability and exposure of human communities and other things of value. This means that we should acknowledge more pathways by which human agency contributes to the climate problem and, accordingly, a different landscape of contribution-based remedial responsibilities. (shrink)