Politicizing science is always bad. But James Hansen seemed quite determined to do that. It's even possible to note that NASA has an interest in Mars missions.... although that seems extremely farfetched. But who knows?

If iron seeding works and causes no calamity we can't handle, we'd be derned fools not to do it at some point, assuming we need to of course.

Then again, what is the preferred equilibrium for the planet and how do we know that? There wasn't always widespread environmentalism and I've heard the idea that environmentalism in its present form emerged only after computers became more widespread ( from "All Watched Over By Machines..." by Adam Curtis.)

Is that crackpottery or is it a salient observation? I can't even tell any more.

I don't really get to term myself an environmentalist at all, because I'm absolutely in favor of a "stewardship" model of using the earth's resources- meaning, in this case, that if we see fit to set the equilibrium point to some other level, then we should do so guiltlessly- however, my major concern is that we haven't successfully managed to create long-term viable ecologies via planning yet. We don't understand the many complexities associated with organisms yet -we understand a LOT, but there is a LOT MORE to understand before we can replicate nature through artifice!

Under that view, things like biodiversity are valuable because they contribute to systemic stability - we can exterminate a species if we need to, nobody has to give us any further 'right' to do so (as in a typical attidue, "What gives you the right to play God with Nature?!")- but it is wise to take a preservationist attitude until we have a proven track record of creating long-term, moderately stable ecological systems - until we can replicate our 'Starship Earth,' we'd do well to keep from destroying it! In other words, at least for me, the currently preferred equilibrium point is one that maintains a semblance of the historical ecology's relative balance, because that's the kind of point where I and my descendants get to not go extinct, and once we can reliably replicate and control such ecologies, it won't matter much anymore, we'll be in a position to choose what happens to which things - right now is the tender point where can destroy naturally developed situations, but cannot reliably replicate them.

But we have much about which to be humble. It's always the sort of thing where - if we can do it and it causes less harm ( and we're dead certain that this is true ), then do it.

The shock from "All Cared..." is - what stability? Which equilibrium? If we choose them, how do we defend our choices? Obviously, nobody was doing this 70,000 years ago ( at least presumably not consciously ) and here we are, so...

To a single-digit approximation, all species are extinct. Is it hubris to think we're smart enough to keep from destroying ourselves, or that we're powerful enough to destroy ourselves?

Suppose we add Pigou carbon taxes. Does that mean poor people suffer more? So can we exempt them? Then isn't that sort of ... Empire-ey, the sort of thing a 19th Century Brit like Rudyard Kipling wrote about?

I find the various anthropic principles to be of good use for this sort of thing.