I've read a few of KSR's more recent books but I'm just now getting around to the one he's most known for. It's interesting to see that his environmentalist mindset and hatred of capitalism were already present in the early 90s. I guess he skipped the libertarian / ancap phase that many sci-fi authors seemed to go through (or maybe that's just a bubble I was in?).
The character Ann represents the most extreme environmentalist viewpoint: she is desperate to preserve Mars in its natural state, inconsolably depressed by the prospect of any terraforming. I think you could draw a connection between this impulse and, for example, NIMBYism in contemporary politics: when we come to know and love something beautiful (be it a rugged alien landscape, or a quaint low-density neighborhood of historic buildings), we can become fixated on preserving it, insensitive to the costs we impose on others by doing so. But in a universe subject to the first law of thermodynamics, the creation of something new must always be paid for by the transformation of something old. It isn't reasonable to try to hang on to every piece of beauty forever; we have to make space for new people, and for the new beauty they will embody and create.
Certainly it's worth preserving some - much! - of the past, but there has to be balance. There are, to put it mildly, a lot of planets out there. Demanding that they all be preserved untouched would be about as reasonable as demanding that every single meadow on Earth be declared a state park.
In Ministry for the Future Robinson imagines a cryptocurrency paid out for the prevention or negation of carbon emissions. Red Mars likewise gestures (vaguely) at a proposal for remaking the economy on a more ecologically-aware basis: "eco-economics" where calories are the fundamental unit of value. This doesn't sound promising to me. For one thing, calories don't even capture all of humanity's physical needs (how should this system value nutrients that are needed for full health but not survival, for example?). And as the book notes, a caloric value would have to be assigned to things like art arbitrarily. Assigning such value by fiat of a central authority sounds much more dystopian than our current system.
The character Arkady makes an interesting plea for engineering a new social order, pointing out the discrepancy between our control over the physical world and the haphazard nature of our social world:
...we have technology to manipulate matter right down to the molecular level. This is an extraordinary ability! Think of it! And yet some of us here can accept transforming the entire physical reality of this planet without doing a single thing to change ourselves or the way we live.
But I think the analogy fails in two obvious ways. Reshaping the physical world can be done unilaterally (by an individual or group) as long as nobody more powerful cares enough to stop them; social change depends on a greater degree of consensus, and achieving consensus is very difficult. It's also especially difficult to scientifically determine what the impact of social policies will be - you can't run rigorously controlled experiments in economics nearly as easily as you can in physics.
One amusing observation in the book is that the project of initial colonization needs to find people "crazy enough to want to leave Earth forever, but sane enough to disguise this fundamental madness, in fact defend it as pure rationality, scientific curiosity or something of the sort..." The screening process for the mission searches for a psychological profile so unrealistic that in practice they're selecting for liars.
I must admit I zoned out a lot during the audiobook and I don't know whether that's a symptom or a cause of me liking this less than other KSR novels I've read.
Unrelated to anything, here's a nice quote:
I suppose it's this that makes me somehow happy. Have we ever been so free of choices? The past is wiped out. All that matters is now. The present, and the future. ... And, you know, you never really summon all of your strength until you know that there's no way back, no way to go but onward.