Whether cloud seeding is effective in producing a statistically significant increase in precipitation is a matter of academic debate, with contrasting results depending on the study in question and contrasting opinion among experts.[12]
A study conducted by the United States National Academy of Sciences failed to find statistically significant support for cloud seeding's effectiveness. Based on its findings, Stanford University ecologist Jerry Bradley said: "I think you can squeeze out a little more snow or rain in some places under some conditions, but that's quite different from a program claiming to reliably increase precipitation."