A question: why anything about global warming gets downvoted, even popularly readable explanation of the fairly mainstream scientific consensus? edit: Okay, this is loaded. I should put it more carefully: why is the warming discussion generally considered inappropriate here? That seems to be the case; and there are pretty good reasons for this. But why can't AGW debate be invoked as example controversy? The disagreement on AGW is pretty damn unproductive, and so it is a good example of argument where productivity may be improved.
The global warming is a pretty damn good reason to build FAI. It's quite seriously possible that we won't be able to do anything else about it. Even mildly superhuman intelligence, though, should be able to eat the problem for breakfast. Even practical sub-human AIs can massively help with the space based efforts to limit this issue (e.g. friendly space-worthy von Neumann machinery would allow to almost immediately solve the problem). We probably will still have extra CO2 in atmosphere, but that is overall probably not a bad thing - it is good for plants.
For that to be important it is sufficient to have 50/50 risk of global warming Even probabilities less than 0.5 for the 'strong' warning scenarios still are a big factor - in terms of 'expected deaths' and 'expected suffering' considering how many humans on this planet lack access to air conditioning. I frankly am surprised that the group of people fascinated with AI would have such a trouble with the warming controversy, as to make it too hot of a topic for an example of highly unproductive arguments.
I do understand that LW does not want political controversies. Politics is a mind killer. But this stuff matters. And I trust it has been explained here that non-scientists are best off not trying to second guess the science, but relying on the expert opinion. The global warming is our first example of the manmade problems which are going to kill us if there is no AI. The engineered diseases, the gray goo, that sort of stuff comes later, and will likely be equally controversial. For now we have coal.
The uFAI risk also is going to be extremely controversial as soon as those with commercial interests in the AI development take notice - way more controversial than AGW, for which we do have fairly solid science. If we cannot discuss AGW now, we won't be able to discuss AI risks once Google - or any other player - deems those discussions a PR problem. The discussions at any time will be restricted to the issues about which no-one really has to do anything at the time.
There's a three-pronged answer to this, as I see it.
First: there's a tacit moratorium on partisan-coded issues around here which do not directly concern the science of rationality or (to a lesser extent) AI. Even those on which a broad consensus exists: the reasoning most often given is that a vocally partisan position on such topics would position LW to attract like-minded partisans and thus dilute its rationality focus. The politics of religion is something of an exception; it's essentially treated as a uniquely valuable example of certain biases, though I suspect that status in practice has more to do with the grandfather clause. Anthropogenic global warming is not a uniquely valuable example of any bias I can think of; it's a salient one, but salience often comes with drawbacks.
Second: LW is not a debunking blog, nor a forum dedicated to cheering scientific consensus over folk wisdom, and it should not be except insofar as doing so serves the art and science of rational thinking. There's considerable overlap between LW's natural audience and that of sites which are devoted to those topics, which has on occasion misled (often ideologically opposed) newcomers into thinking it's such a site, but even if a general consensus exists that LW's theory and practice tends to lead to certain positions, it behooves us to guard against adopting those positions as markers of group identity. The easiest way to do that is not to talk about them.
Third, and probably most embarrassingly from the standpoint of healthy group epistemology: by the last census/survey LW is disproportionately politically libertarian, though adherents of that ideology are an absolute minority ([left-]liberalism is slightly more popular, socialism slightly less, other political theories much less). The severity of, proper response to, and to a lesser extent existence of anthropogenic global warming remains an active topic of debate in libertarian circles, though less so in recent years. Higher sensitivity to AGW than to other conservative-coded positions may in part be a response to these demographics.