Yes the environmental impact of an AI agent performing a given task is lower. However we will not simply replace every programmer with an agent: in the process we will use more agents exceeding the previous environmental impact of humans. This is the rebound effect [0].
Your reasoning could be effective if we bounded the computing resources usable by all AI in order to meet carbon reduction goals.
Your reasoning could be effective if we bounded the computing resources usable by all AI in order to meet carbon reduction goals.
[0] https://en.wikipedia.org/wiki/Rebound_effect_(conservation)