'This Earth of yours will be reduced to a burned-out cinder.'The hapless 2008 remake didn't seem to know what it was saying by the end, but it had two basic novel ideas:
- Extend the galactic police force's powers so that they can kill all the humans without toasting (and in fact pointedly, pristinely preserving) the rest of the planet
- Broaden the aliens' essential interests from galactic order to order down on Earth as well, i.e., the remake's aliens damn humans not just (or even especially) as unrepentantly aggressive and dangerous generally but also as environmentally cavalier/dangerous to other life on Earth specifically
expresses the same genocidal fascist fantasy/temptation as the two DtESS films, and even shares the 2008 remake's exact emphasis. Yet reactions to the DtESSs have always been muted, whereas Curtis's film was an overnight, sensational disaster. Why?
On the one hand, the details almost certainly make a difference: we don't see Klaatu and Gort et al. butchering kids. And presumably the lifespan of Curtis's film would have been extended if Curtis had eschewed direct, Cronenberg-style explosion shots in favor of, say, just 'horrified reaction' shots (thereby leaving us to infer what happened), let alone if Curtis had told a much less (or even non-)violent story. On the other hand, genocidal violence, whether eco-inspired or not, just does seem easier to take when the Final Solution-bearer is external/impartial rather than one/some-of-us. We've plenty of cultural practice with the former case from the Torah and Old Testament generally, but that practice absolutely doesn't transfer to righteous, eliminationist forces that are one/some-of-us. Rather, it's conventional wisdom that some-among-us will always fancy themselves as Jehovah/Yahweh-figures judging and damning us all, and that such people always have to be monitored and, if necessary, stopped. The moral seems to be that while environmentalists can try to point to Nature's judgment on human civilization, say, they can't, with profit, be caught imagining that they are avenging angels of that judgment. That said:
or even this. Slightly illicit, avenging angel fantasies are big business, and a big part of the business in which Richard Curtis makes a living in particular.
 Update: imdb's ecarle reminds me that Klaatu depicts his home world as ruled by pervasive terror of summary execution:
"For our policemen, we created a race of robots...In matters of aggression, we have given them absolute power over us. This power cannot be revoked. At the first sign of violence, they act automatically against the aggressor... The result is, we live in peace, without arms or armies"Dirty Harry raised to the power of Robo-cop on every corner. Very peaceful, no fire-power in that picture, no sir.
 E.g., suppose the 'no pressure' speeches mention the superheated, acidic surface of Venus as a model for a high-GHG earth. When the red-buttons are pushed, people simply disappear. Later it's revealed that they've been teleported to:
INTERIOR OF ROOM ON VENUS
The 20-25 people inside the room, including many of those we've earlier seen disappear, are gathered nervously around the room's single large window. 3/4 of the room is fairly empty, but every few seconds, a new person pops into existence including - Bing! - one of the schoolchildren from earlier.
EXTERIOR VENUS HELLSCAPE
Close up on an external digital thermometer with dual Celsius and Fahrenheit displays. It ticks over from 460 to 461 °C, 860 to 861 °F. Some more droplets of sulphuric acid rain hit the thermometer's exterior, melting part of the Fahrenheit display. Focus drops back (or Cut) to regretful faces of climate change skeptics of various ages pressed up against the large window. We hear the sound of another person popping into existence behind them. Bing! The heavily accented Tottenham Football coach from earlier starts in mid-prattle.
CLOSE UP LOOKING IN THROUGH LOWER HALF OF WINDOW
Faces of horrified school-children, including the child who just materialized pushing in past adult legs to get a view out. Their eyes widen as more sulphuric acid rain and smouldering, dissolving crud spatters and slides down the window in front of them while, from somewhere behind them, the adult, know-nothing, Football coach voice prattles on...
 To be sure, lefties, let alone enviro-lefties in particular, are probably a minority of apocalyptic fantasists, especially in the US. The Timothy McVeigh/far-Right/quasi-secessionist end of US political life is currently booming, much as it did during the Clinton years.