Most cost effective, I think, would be to engineer a particularly potent bacteriophage. Aren’t genetic scientists getting close to this ability? The virus would only need to target one or two bacterial types, e.g. rhizobacteria, essential for higher life.
In any scenario I’m afraid some bacteria and higher forms would survive. If plans required on-going destructive measures, the complete collapse of civilization might prevent execution. Still, eliminating a few major classes of organisms, e.g. the mammals, might be doable. Will this satisfy OP?
We don’t even know if this has managed to kill all life on Venus, let alone that it would do it here where life has had a few extra billion years to entrench. How would your plan kill, oh, say all of the life 10 or 20 kilometers underground? Or in the upper atmosphere (where life on Venus might still be holding on)? Even if you could recreate the exact same environment that is on Venus here on Earth I don’t think you’d kill everything. And, of course, it’s gonna be a bit harder to do, since the Earth is further away (as well as several other factors that Venus enjoys that the Earth doesn’t have).
No, you need to drop something big on the planet going really, really fast. Maybe figure out a way to shift Mercury in it’s orbit at just the right time and place to send it into the Earth. Or one of the really big moons or asteroids with a few gravity assist boosts in speed to get it up to a decent speed before crashing it into the planet.
You’re right, I didn’t plan for the life 20km underground. The only solution is to throw the Earth into the Sun somehow. How can we do this? Gravitational slingshot. One carefully aimed pebble thrown into the right part of our solar system could disrupt the orbit of a slighter bigger rock, which in turn moves a larger rock, which moves an astroid, which moves a bigger astroid, and so on until a small moon is moved in such a way as to move a bigger moon until planets are singing their way across the solar system before finally catapulting the Earth into the Sun. Pretty straight forward really. I’ll let others do the maths.
The gravitational and kinetic energies that must be converted in the amplifying slingshots to cause a major collision are stupendous. Yes, you can in principle use a cascade of slingshots to achieve high amplification but huge precision would be needed. (Errors would accumulate. And the orbits might take a while to line up — did OP impose a deadline?)
BTW, you desscribed an eight-ball combination, like in pool? When the topic comes up in How will we deflect the asteroid? threads a consensus (not me though!) seems to agree even a one-ball combo is very hard to do.
Two Orion spacecrafts one “north” and the other “south” of the earth, each using half of humanity’s nuke arsenal, crashing into each pole at the same time at maximum speed?
Watching the devastation of the wildfires in California, it got be thinking. If there is mass nuclear exchange using most of the world’s nuclear weapons, won’t the explosions ignite fires that will spread far beyond the blast radius of the bombs? Couldn’t these fires cause as much structural damage as the blast themselves? I can’t imagine there would be much firefighting infrastructure left intact after a nuclear exchange. I admit even this scenario would not be world ending.
That’d give you at most the same total energy as just setting the nukes off on Earth, actually much less because an Orion drive is really inefficient, and even of the energy you delivered most would just be wasted in sending a lot of debris away really fast. And even setting them all off on Earth, spaced for maximum dispersal, wouldn’t even remotely come close.
My tongue was in my cheek when I described it. Without doubt we don’t have anywhere close to even a fraction of a percent of the ability to do this. Yet.
The earth has survived extinction events of catastrophic proportions in the past and bounced back fabulously. As awful as we are, once the earth rids itself of us, it will be just fine.
Creation is a work in progress. I personally believe that, because of humanity’s fatal flaws, it is ultimately doomed to the same fate as its predecessors such as the Neanderthal. I just don’t think we can “cut the mustard” in terms of being the ultimate in intelligent life on this planet, in being the species that takes us to the limits of our solar system and beyond.
The fate of the Neanderthals was to get their butts kicked by us. Who do you think is going to kick our butts? We’ve already eliminated all of the likely contenders (like the Neanderthals and the Floriensians).
Cats. As soon as they evolve opposable thumbs, so they can open cat food without our help, we’re doomed.
Right, Floriensians, also known as hobbits. We’d better be sure there isn’t some undiscovered community of them somewhere, or it’s inevitable that a hero will arise among them and, with the aid of a magician, a mostly useless sidekick, and a romantic love interest, defeat the evil human empire. Happens every damn time.
It’s at least been hypothesized that life has survived even that, with some particularly hardy bugs hanging out in orbit until things cooled off. So however you go about it, you don’t want any orbital-velocity ejecta.