The biggest technology needed is actually excavators so we can dig ditches everywhere to soak up rain water and refill aquifers. Also building retaining walls, terraces and swales using permaculture style water management to reforest degraded grazing lands.
By "the 50s," do you mean the 1850s, when Eunice Newton Foote discovered the greenhouse effect, and calculated that CO2 emissions would change the climate? And when John Tyndall published the same thing, because the scientific community ignored her because she was a woman? Yeah, we could have started 170 years ago, but people just aren't wise enough to do anything about climate change until it's too late.