The RealClimate guys report on a conference on the ethics of climate change. Here's their summary of Henry Shue's presentation:
Henry Shue, a Oxford philosopher well known for his work on such issues as the moral implications of torture and pre-emptive war, made the argument that the moral implications of not dealing with climate change should be thought of not only in terms of harm, but in terms of potential harm. Unfortunately for those of us that would like to keep burning fossil fuels at our current rate, Shue argues that uncertainty — the possibility that harm caused to future generations from anthropogenic climate change will be relatively small — does not get us out of our moral obligation to change our behavior. That is, one need only recognize that business as usual will increase the risk of significant harm – a point that almost nobody debates – for it to be clear that business as usual may be unethical.
Maybe this isn't what Shue actually said, and surely he said rather more, but I find this pretty uncompelling as stated.
First, the idea of obligations to distantly future generations strikes me as incoherent. These are people that do not actually exist, and the people who do eventually exist is a function of what we do and don't do now, which is surely a serious complication. Even if we can imagine determinate future persons to whom we might have duties, it remains that we stand outside the Humean circumstances of justice with them, and so don't in fact have duties with respect to them. I can make sense of an “intergenerational chain” conception of obligations to future generations: I have obligations to my children and grandchildren; my children and grandchildren have obligations to their children and grandchildren; etc. I think this can get us a few general principles, like “leave enough and as good for the kids,” but it's unclear how this can undergird any kind of significant sacrifice for indeterminate far-distant beneficiaries.
Second, even if we can find some ground for obligations to far-future generations, we'd need to be established that “business as usual” will in fact be a net harm to future generations. Suppose a small reduction in future warming requires a small reduction in economic growth every year from now to then. The longer the time frame, the greater the harm to future generations from reduced growth rates. At some point, the loss in standard of living will completely swamp the gains from reduced warming. And, of course, the longer the time frame for significant warming, the less likely it will be that dislocations from warming will be serious. Gradual changes in patterns of capital investment, migration, etc. will move many people out of harm's way, and perhaps move many other into areas that will benefit from warming. And, of course, the more rapid the rate of economic growth, the more likely it is that effective technologies that will retard warming, or mitigate its effects, will come on the scene. The allegedly obligatory deviation from “business as usual” may be in the direction of doing more to accelerate economic growth. It is by no means obvious that this isn't the best course.
Looking at the RealClimate summaries, it seems to me that there is a bit of a bias toward emphasizing the potential harms of warming while de-emphasizing — or even arguing down — anything that might prevent or mitigate those harms. RealClimate's Steig and Schmidt write:
one of the commentators at the conference made the argument that it was an open question whether we had any moral obligation towards future generations for our impact on the climate, since that impact could in principle be averted (for example through carbon dioxide removal via ocean iron fertilization). This is equivalent to saying that we will not have to address the issue of climate change if we address it, an argument that has no bearing whatsoever on whether we have a moral obligation. We were a bit surprised to hear it from a philosopher since it is a tautology (usually anathema to philosophers).
Sounds like the unnamed philosopher may have been saying something close to part of what I was saying above, and it doesn't sound like a tautology to me. It sounds to me like he was saying that if we're thinking about the probability of harm, then we also have to take into account the probability of the emergence of technologies that would prevent that harm because, otherwise, you can't calculate the total probability of harm. Why try to avoid the obvious force of that point? Steig and Schmidt's reply amounts to this, as far as I can tell: If the emergence of this technology is motivated by the recognition of a moral obligation to address the issue, then it weirdly self-defeating to argue that people therefore don't have a moral obligation to address the issue. Sure, but I truly doubt that was the argument. It is confused to talk about whether “we” do or don't address warming. Not everyone invents or even funds new technologies. If someone or other does this in the future, whatever their motivation, and that makes the problem go away, then the problem will have gone away. If the probability of this is high enough, and we know it, then the rest of us non-inventing, non-invention-financing folk, are obviously off the hook right now. Now, I don't know the probabilities of any of these things. And neither does Steig and Schmidt or Henry Shue.