This question resolves true if, looking back in 15 years, it's obviously the case that:

"In 2023, the marginal smart, ethical person should have gone into AI rather than climate"

This question resolves false if it's obviously the case that:

"In 2023, the marginal smart, ethical person should have gone into climate rather than AI"

Resolves n/a otherwise.

I'll assume that in either field the person would work on the top 5% of most effective interventions, as judged post-hoc, and that we're only evaluating impact (not salary, personal fit, other idiosyncratic factors).

How could this be obvious? E.g. if most climate innovations are the products of AI systems and human labor on climate in the 2020s turned out obsolete; if an enormous avoidable-in-retrospect catastrophe or near miss happened in either of these fields.

If in doubt I'll resolve n/a.