Over the last couple years, Greek yogurt has taken over supermarket shelves—what does that mean for the environment and for the cows producing it?

Mother Jones weighed in recently, pointing out that Greek yogurt "requires much more milk to make. For American-style yogurt, the ratio of milk to final yogurt product is about 1:1 (sometimes more like 1.3:1, since many manufacturers add in a little bit of condensed skim milk to improve the texture and protein content), while for Greek yogurt it's often as high as 4:1."

The main, and in theory only, difference between the two is that Greek yogurt involves straining out the liquid whey, which increases the thickness, whereas in regular yogurt, that's left in.

We already know how dairy production alone is responsible for almost three percent of global man-made greenhouse gas emissions. That's a lot for a single food product, so increasing the concentration of dairy required for every yogurt container also increases greenhouse gas emissions by a considerable amount.

I don't think I've ever seen Greek yogurt sold in containers larger than 500 grams—meaning any chance for reducing waste by buying in bulk is washed down the drain. So more milk and more plastic for every yogurt = more damage to the environment.

Increasing demand for milk also increases the suffering of cows producing it.

There's also more food waste involved: the whey that gets strained out is often discarded. The Mother Jones story said that some yogurt manufacturers give their whey to farmers for use as animal feed or fertilizer, but warns that yogurt whey is acidic (as opposed to sweet, the second type of whey), which farmers must be careful with because of its potential to pollute waterways.

To reduce this waste stream, Stonyfield Farm and Chobani are both working on anaerobic digesters to convert the whey into energy.