]]>There's a lot of R&D going on right now on heat pumps that don't use harmful refrigerants, or use alternatives to the common compression/expansion models. But heat pumps all dump waste heat somewhere, so using an air conditioner to cool one place means heating up another place.
Contrast that to older methods of cooling spaces that have no such downside. I'm thinking of things as simple as shading buildings with deciduous plants, or building them tall and close together to minimize solar gain, or building for cooling air flow using stack effects, or even going so far as using airflow over cisterns or building qanats and wind towers or wind catchers.