https://www.frontiersin.org/articles/10.3389/fsufs.2019.0008...
Looking at yields only (which is a small part of the study; sustainability depends on many other factors) it looks like log response ratio for organic vs conventional is -0.4 (but depends on crop type, etc, see figs 5,6). This response ratio means organic yields were typically ~2/3rds of conventional across US, EU for most produce types.
I think a real path forward is reduction of pesticide/herbicide usage through highly targeted techniques, as well as greater embrace of biodiversity in the field (even at some cost to yield). However it is also not reasonable to switch to all organic right now, since we would then produce only 2/3rds the food we have now.
I think where move from conventional is most critical is for animal products. “Conventional” in the US comes with lots of cruelty. Even if we net eat less meat supporting meat sources that treat animals better is important, and will not likely cause net decrease in calories produced.
They looked at yields on a longer term and discovered, that after a transition phase of around 5 years the numbers were comparable, but with organic agriculture realizing better yields in times of draught.
Additionally they looked at caloric yields per acre. I just grabbed an explanatory blog post from said institute:
https://rodaleinstitute.org/blog/can-organic-feed-the-world/
Edit: Looking a bit further rodale has rest years that they don’t count for their organic fields. 25% of the years they literally don’t grow anything on a given plot, but they only compare the growth years.
It I am totally aware of studies like Verena Seufert et al. showing reduced yields between 5 to 39% depending on the context and used methodologies.
Edit: Regarding rest years. At least were I live both, organic or non organic farmers do that. Not sure how it is in other parts of the world.