Unfortunately there is little evidence that cloud seeding is actually able to increase the overall precipitation in most cases [0 - response to NRC report on cloud seeding].
There are spectacular results when glaciating individual clouds [1] and there is some evidence of glaciogenic cloud seeding (the kind done with silver iodide) working in mountainous regions where supercooled clouds are common [2 - paywalled unfortunately]. However, much of the Tibetan plateau has high amounts of dust, which means that the clouds already form ice at relatively warm temperatures [3]. In this case, silver iodide might not be expected to have a large effect on precipitation formation.
It is also very difficult to detect a change in precipitation, as it varies strongly in both space and time, requiring long averaging periods to detect a change. This will be an very useful experiment if it goes forward, but I suspect that concerns over rain-stealing are rather overblown, as are hopes that it could significantly enhance rainfall in arid regions.
There are spectacular results when glaciating individual clouds [1] and there is some evidence of glaciogenic cloud seeding (the kind done with silver iodide) working in mountainous regions where supercooled clouds are common [2 - paywalled unfortunately]. However, much of the Tibetan plateau has high amounts of dust, which means that the clouds already form ice at relatively warm temperatures [3]. In this case, silver iodide might not be expected to have a large effect on precipitation formation.
It is also very difficult to detect a change in precipitation, as it varies strongly in both space and time, requiring long averaging periods to detect a change. This will be an very useful experiment if it goes forward, but I suspect that concerns over rain-stealing are rather overblown, as are hopes that it could significantly enhance rainfall in arid regions.
[0] - https://journals.ametsoc.org/doi/abs/10.1175/BAMS-86-5-647
[1] - https://www.ge.com/reports/snow-men-cometh-kurt-vonnegut-ice...
[2] - http://www.pnas.org/content/115/6/1168
[3] - http://www.pnas.org/content/107/25/11211