I suspect that unless there is a consensus or at least a large majority in favor of it, nothing will be done.
Lets say the EU does geoengineering and then there are crop failures in India the next year. Their fault or not, they are going to get blamed for it and actions taken. The EU would become the scapegoat for any kind of weather/climate issues in future.
This is the trolley problem done at a global scale.
>Lets say the EU does geoengineering and then there are crop failures in India the next year.
Who cares? Tell them to go pound sand or stop burning so much coal.
Countries are already water seeding. This kind of worry that someone might complain about the eu trying to save itself is so low on the list of things that matter. Let them complain, and the eu can complain about all the other countries geoengineering by burning fossil fuels.