There are good reasons to oppose geo-engineering, it will cost billions, there will be unintended consequences and there are political issues. The sulphur dioxide idea in the upper atmosphere has been heavily criticised, but this is different.
But the alternative of not doing geo-engineering is worse and more expensive. If the AMOC collapses it is too late.
Global warming threatens to destroy our civilisation and the current situation is much worse than predicted. it is time to start geo-engineering.
A massive release of SO2 into the atmosphere has been suggested and, for the moment , rejected. The SO2 is a negative greenhouse gas. The clean up of marine oil fuels reduced the man made SO2 during the last decade. SO2 may destroy Ozone and cause acid rain.
Here a different simple idea is explained.