A footnote in this good discussion of discounting
Similarly, discounting for opportunity costs is also inappropriate if one is comparing outcomes that cannot be invested. For example, although money can be invested and (perhaps) be used to save future lives, a life itself cannot be "invested" to offset or negate lives lost in the future. Consider the following thought experiment: Two asteroids are threatening to collide with earth. The smaller asteroid is projected to collide with earth in 10 years, killing a few hundred people. The larger asteroid is projected to collide with earth in 1000 years, killing a few billion people. NASA can blow up one of the asteroids, but not both. If future deaths were discounted at the market interest rate, blowing up the small asteroid may be judged to be more worthwhile. However, defending that choice with an opportunity cost argument requires an account of how the people who are saved from the smaller asteroid can be "invested" to compensate for the much larger loss of life that will later occur when the larger asteroid collides. It is difficult to understand how that would work. (The people who are saved by preventing the impact of the small asteroid could, through reproduction, create more people, but it would be strange to interpret this as compensation for the later loss of life.)
(I'm not sure why the interpretation in the ending parenthetical is strange. Comparing the lives of actual living people to hypothetical not-yet living people isn't strange.)
Wouldn't the technology that NASA invents in order to blow up the first asteroid be used to build better technology to blow up the second asteroid? "Blowing up an asteroid" isn't consumption and I don't see why there's any problem with time preference for technology
Rhetorical note: if the hippies (I kid!) want me to care about this whole save my great grand kids from the CO2 monster thing, they should engage my inner geek. They shouldn't be asking for "reductions in consumption" (boring!) they should be asking for "investments in crazy mind blowing biosphere-engineering gadgets." If they mention robots and drilling holes to the planet's core, I'm so in.
The industrial-military complex folks got us geeks behind the cold war by, literally, promising the moon. And look, now we have Teflon to show for it.