What? Says what? Their research was only looking at the nutritional differences.
As for environmental impact of organic farming, from what I know, in order to get the same amounts of produce we'd need to expand existing farms much more because organic farms give lower yields. If people ate less, that might help the situation and others, but that's unfortunately unrealistic. Instead given our track record, if we all switched to organic, we'd just destroy some forests. The other alternative is shrinking the human population quite a lot, but I do not like that idea at all.
I think that many people who champion organic have some crazy superstitious assumption beneath many of their claims, and that this assumption is that nature is benevolent, some kind of caring mother, probably called Gaia. Unfortunately nature is not benevolent, and our lives are so much better now because we've managed to subdue much of nature. During all the time we've been evolving we've had to adapt to fit in with nature. We've finally, in the last hundred years or so, been able to change things and make nature fit in with us instead. Though there are still many natural events that we can't control.
