[A]doption of GMOs does, in fact, increase ultimate crop yield. The myth that they don’t is mostly due to the persistent anti-GMO smear campaign, largely funded by the organic industry, but is helped by several layers of confusion on this issue.
[I]t is clear that Bt [insect-resistant crop] varieties have decreased pesticide use, and herbicide tolerant varieties have increased glyphosate use but decreased the use of more toxic herbicides. They have also increased yield – but indirectly …. These early GMO traits were never designed to directly increase yield. They were designed to help farmers by reducing their need to apply pesticide, or by making it easier to apply herbicide and reduce the need for tilling or expensive hand weeding. So it is a non-sequitur to say that traits never designed to increase yield did not increase yield.
But even more importantly – these traits did increase crop yield, indirectly. A recent review found:
The analysis of over 6,000 peer-reviewed studies covering 21 years of data found that GMO corn increased yields up to 25 percent and dramatically decreased dangerous food contaminants. The study, published in Scientific Reports, analyzed field data from 1996, when the first GMO corn was planted, through 2016 in the United States, Europe, South America, Asia, Africa and Australia.