This is compelling evidence summarized by Kathleen Willcox in Wine Searcher:
Multiple studies of scores from Robert Parker, Wine Enthusiast and Wine Spectator have shown that organic wines perform better than their peers.
In 2016, Magali Delmas and Olivier Gergaud, professors at UCLA and the KEDGE Business School in Bordeaux looked at 74,000 scores of wine produced in California from the trio above, and found that organically and/or biodynamically certified wines earned 4.1 percent higher than the rest of the pack.
The duo returned in 2021 with the results from a study that considered 128,000 wines scored by top French guides Gault Millau, Gilbert Gaillard and Bettane Desseauve, showing that organically certified wines scored 6.2 percent higher scores on average than the rest. Biodynamically certified wines – which don’t just eschew chemicals, but also require growers to plant and harvest at certain times and integrate animals and native plants into a holistic and closed-loop farming system – earned 11.8 percent higher scores.
Most of these wines were likely tasted under at least single-blind conditions meaning the critic doesn’t know the producer of the wine they are evaluating. Thus it is unlikely the results are skewed by a bias the critics might have toward environmentally-sound farming practices. The 11.8% higher scores for biodynamic wines is especially impressive.
The article goes on to probe the reasons why sustainable farming practices might lead to better wines. The hypotheses range from greater resistance to oxidation, higher acidity, better disease resistance, greater efficiency in absorbing nutrients, increased microbial activity in the soil, etc. Or it may just be that farming biodynamically requires that the winemaker think more deeply about viticulture and pay a lot more attention to each individual vine thus allowing them to identify problems more quickly.
There is a debunking hypothesis that can’t be ruled out.
Joshua Greene, editor and publisher of Wine & Spirits, isn’t convinced that organic and biodynamic farming practices make wine taste better.
“It’s an illusion,” Greene says. “I don’t think that organic and biodynamic farming make the wine better, I think that there are just a lot more high-level vineyards using organic and biodynamic farming methods.
Perhaps. But that could be tested by looking at scores for wineries before and after converting to sustainable farming methods (although score inflation would be a confounding variable.)
In any case, this is a purely hedonistic reason for seeking out wines produced with environmentally sound farming practices.
Exploring the Philosophy of Food and Wine 