Scientists have seen the future, and it is neither delicious nor satisfying. Or at least that’s the considered judgment of a panel of distinguished doctors and researchers, who recently published the “Planetary Health Diet," in the British medical journal Lancet. By 2050, the world population is expected to hit 10 billion, and with the threats posed by climate change and other environmental concerns, the scientists say we’re going to have to radically change our diet to save the earth. Accordingly, they make exacting recommendations about what we can eat if we want the planet to continue to accommodate us. The most restrictive aspect of the diet is that a person of average size is graciously allowed 78 grams of meat a day, which works out to be a little more than a pound of meat...