[tome]

> This species at present could wipe out almost all life from the planet (if it wanted, which it doesn't) in multiple ways

That's interesting. How could it? Please present a plausible scenario (more plausible than "The US president decides to cover the globe with nuclear explosions, and everyone with any degree of influence over the process just lets him do it").

[cobaltblue]

My parenthetical is important. The "it doesn't [want to]" is precisely why many ideas won't work, because many adversaries within the species (the rest of us) will work against anyone trying, and getting enough people with the know-how and desire to try will be hard. In fact the hardest part of the fragment you pulled out is developing a strategy that will indeed end almost all life without first killing all humans. A lot of strategies are likely relatively long-term (and inplausible to actively work on because of adversaries, however some believe human activity is already an ongoing inadvertent mass-extinction event for other life and maybe ourselves eventually). However the thing in my mind when I wrote that was intentional asteroid impact. We've already demonstrated we can land on the things, NASA's been busy finalizing the details of a redirection mission, so redirecting a sufficient number of smaller ones or just one really big one (but why stop at one?) ought to do the trick for most plant and animal life.

[arethuza]

Cobalt salted hydrogen bombs are one fairly plausible route - how many and how large they'd need to be is another question.

https://en.wikipedia.org/wiki/Cobalt_bomb

[Of course, they don't exist at the moment - but they wouldn't be that difficult to make as one advantage of a Doomsday bomb is that you don't need to deliver it so it can be made as large as you want through staging].

[tome]

Interesting. So the idea is that a small group of people could unilaterally build and detonate one of these without anyone else being able to stop them?

[arethuza]

In David Brin's novel Earth World War 3 is basically the world vs Switzerland - with the Swiss threatening to detonate large cobalt bombs buried under the Alps.