The scale of your perspective is of little importance.

There exists objective, observable evidence of the fact that life has cycled continuously throughout the existence of this planet and there is none to suggest that this will change at any significant point in the future.

Well, you are correct that Earth’s nuclear weapons are literally a poofing fart compared to the energy we could potentially get from the sun, and we do have precedent for the sun creating extremely hostile conditions due to greenhouse gasses in one of our nearest neighbors, Venus.

But we need to examine what we’re talking about here specifically. I am not a geophysicist so I don’t have the numbers, but in order for your “concern” to have teeth you would need to show that there’s anything we can do here and no or even in the next thousand years that could change the nature of Earth’s atmosphere enough to replicate the kinds of conditions that created Venus’s current conditions.

And not only that, you need to compare what we could possibly do, even intentionally, that would come remotely close to some of the other greenhouse heating events that we’ve experienced in the past, and we’ve had some real doozies. We’ve had Earth heat up to scorching conditions from the planet turning inside-out several times, we’ve had Earth become a giant ice-ball. We’ve had impacts in the distant past that make the Chicxulub impactor look like a bottle-rocket misfire. And still, Earth regained equilibrium enough to support life. Over the last 4.5 billion years or so it doesn’t appear we’ve experienced anything that turned Earth’s surface and subsurface hostile to all forms of life, so it’s pretty safe to say that unless we start deliberately steering planetoids into our crust, which isn’t out of the question knowing our warlike ways, we’re probably not going to unintentionally create Venus-like conditions on Earth.

And of course we have to address the fact that we’re not even sure if Venus is sterile, there are increasing signs of bacterial life in the atmosphere so it’s quite possible that once life gets a foothold it may be incredibly hard to dislodge.

This isn’t an argument against the serious threat that we pose to the ecosystem, or to say that we’re not in extreme danger of ruining the current biosphere of the planet, we are in fact in the middle of a human-made mass-extinction. It’s not good. Our worst-case scenario sees a planet completely devoid of ice, no clouds, an atmosphere that consists of a hot haze that heat can’t escape from for thousands of years and an ecosystem collapse killing off most land animals. But it won’t be the end of life. Just another setback.

This is important to make clear because truth is important, speculation is not helpful when it points out unlikely extremes, it gives ammunition to deniers when you proclaim factually improbable extremes. Things are absolutely going to get bad, but there’s no reason at all to hype it to an extreme or you shoot yourself and your cause in the face.