There are good arguments to be made for allowing duplexes in neighborhoods zoned for single family use. Climate change is not one of them.
If the city of Bloomington, Indiana poured all of its energy into fighting climate change, we could not change the temperature by one billionth of one percent of one degree. A single small city in the Midwest cannot do that.
Citing “climate change” as an argument for duplexes is virtue signaling, not serious public policy.