there’s still that nasty 50 year lag between emissions and atmospheric outcome

Are you sure about that?

Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries. There is a time lag between what we do and when we feel it, but that lag is less than a decade.
https://climate.nasa.gov/faq/16/is-it-too-late-to-prevent-climate-change/