In the outside world, the problem isn’t that plants are suddenly getting more light: It’s that for years, they’ve been getting more carbon dioxide. Plants rely on both light and carbon dioxide to grow. If shining more light results in faster-growing, less nutritious algae—junk-food algae whose ratio of sugar to nutrients was out of whack—then it seemed logical to assume that ramping up carbon dioxide might do the same. And it could also be playing out in plants all over the planet. What might that mean for the plants that people eat?