What if it's only 99.99% sure that CO2 is the reason for climate change? What about 90%? No need to act until we bring that up to 100%?
What's with the fixation on 0.04% as a number? Things can't have huge impact unless numbers are also big? I don't want to offend, but that's honestly third grade mentality.
There's surprise about small things having little impact, and then there's denial hidden as feigned curiosity. Especially when the answers are directly available from much more credible sources than random internet posters.
Compare with:
"Has it yet been absolutely proven 100% that the lead comprising 0.03% [hypothetically - for reference, this is 100000x the FDA limit] of our food intake is the main culprit/control knob which controls brain development?"
No, it actually isn't the "main" control knob. And our bodies are also complex with many feedback loops. And no study will ever reach p = 0. And it's a really small number. And yet we have made "extremely huge decisions" regarding what fuels we allow, what tests food have to undergo etc...
This is a loaded question ( https://en.wikipedia.org/wiki/Loaded_question ), since it implies that this question-asking is honest and straightforward.
On the contrary, it seems like OP is "jaqing off" ( https://rationalwiki.org/wiki/Just_asking_questions ); unless, of course, they can absolutely prove 100% that they're acting in good faith.
In contrast, OP's hunch about the climate emergency either not existing because the concentration of anthropogenic CO2 in the atmosphere is "small" (according to some unspecified criteria), and/or fixing itself due to plant growth, run counter to the consensus position of the world scientific community, and hence the burden of proof is on OP https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)
It was their choice to raise that burden to the unachievable height of '100% absolute proof' :)