Loren Pechtel wrote:wkernochan wrote:All right, I'll bite on this one. The reason I was disappointed was apparently very different from those featured in the thread. My objection is that in the aliens' plans to ethnically cleanse Earth, they failed to even consider the possibility of simply allowing the humans on Earth to implode due to failure to adequately handle climate change -- either by letting it happen or by surreptitious moves to increase carbon in the atmosphere.
This kind of concept is now such a presence in science fiction that at the least Peerless Author should have had the aliens consider it.
My kindest guess is that the original book was written at a time when climate change was not so widely understood, even in the scientific community, and that it simply didn't occur to PA that the new understanding changed the premise of the book.
I will also add that I'm perfectly comfortable with the deus ex machina. To me, the point is that even with the spunky, inventive humans being involved, successful resistance was not going to happen without that deus. It was a nice twist on the usual scifi trope whose ultimate absurdity was shown in the jawdropping handwavium of the movie Independence Day.
I think they want the planet to live on, they don't want the ecology destroyed.
OK, I am guessing that you are conceding that it isn't obvious why Peerless Author didn't discuss this.
Here's my answer(s) as to why that's probably not the aliens' motivation: There's a big difference between destroying most of the ecology of Earth and having nothing to live on. If I am not in a tearing hurry, as an alien I can simply let things happen, which might mean within a few hundred years destruction of 80-90 % of living beings, including taking human population below a billion (starvation, disease, etc.), with the survivors much less capable of resisting a takeover (and remember, serious xenobiologists and xenophysicists think there's a serious possibility that humanity will be wiped out entirely as a species, so this is not a worst-case scenario but a "middle-case" one). As in the terraforming of Safehold, I would then "xenoform" Earth, introducing my own plants and animals, a process made much easier by the preliminary die-off. If I have ways of sucking carbon out of the air and depositing it underground, restoring the climate to a "Goldilocks" state, then I would need to use them whether I invaded now or not, since 2-3 degrees C of global warming since 1850 are already baked in.
Now suppose I were to go ahead and invade and I succeeded (more or less the scenario until the final few pages). At minimum, I still have billions of people out there who I have to keep an eye on or terminate -- half the world is in cities and half not. As noted, I still have to do something about the fluctuating climate. Since humans are now intermixed with the ecology across most of the planet, simply eradicating humans will cause a huge die-off in the ecology, while likely creating the "rubble of war" in prime xenoforming locations. Failure to maintain dams will mean catastrophic flooding in some areas; failure to maintain sea-walls and levees plus sea-level rise will mean destruction of prime agricultural land. At the end of the day, the ecology will not be as degraded as in strategy 1, but the costs and difficulties of repair and upgrade to "alien liveable condition" are far greater.
