IN AGRICULTURALRESEARCH, it’s been understood for some
time that many of our most important foods have been getting less
nutritious. Measurements of fruits and vegetables show that their
minerals, vitamin and protein content has measurably dropped over the
past 50 to 70 years. Researchers have generally assumed the reason is
fairly straightforward: We’ve been breeding and choosing crops for
higher yields, rather than nutrition, and higher-yielding crops—whether
broccoli, tomatoes, or wheat—tend to be less nutrient-packed.
2004, a landmark study of fruits and vegetables found that everything
from protein to calcium, iron and vitamin C had declined significantly
across most garden crops since 1950. The researchers concluded this
could mostly be explained by the varieties we were choosing to grow.
Loladze and a handful of other scientists have come to
suspect that’s not the whole story and that the atmosphere itself may be
changing the food we eat. Plants need carbon dioxide to live the same
way humans need oxygen. And in the increasingly polarized debate about
climate science, one thing that isn’t up for debate is that the level of
CO2 in the atmosphere is rising. Before the industrial
revolution, the earth’s atmosphere had about 280 parts per million of
carbon dioxide. Last year, the planet crossed over the 400 parts per
million threshold; scientists predict we will likely reach 550 parts per
million within the next half-century—essentially twice the amount that
was in the air when Americans started farming with tractors.