Tag Archives: CO2. crops

A Disquieting Possibility

Could climate change be making us fat? Politico has published an article from a series on the future of health that suggests the answer may be yes.

The article began by describing a 1998 experiment in which scientists made algae grow faster in order to provide more food for zooplankton. They increased the algae by shining more light onto them, and gave the  zooplankton more to eat. But rather than flourishing, as expected, they began struggling just to survive.

The increased light was making the algae grow faster, but they ended up containing fewer of the nutrients the zooplankton needed to thrive. By speeding up their growth, the researchers had essentially turned the algae into junk food. The zooplankton had plenty to eat, but their food was less nutritious, and so they were starving.

A mathematician and biologist named Loladze was intrigued–and spent the next 17 years exploring the obvious question:

Could the same problem affect grass and cows? What about rice and people? “It was kind of a watershed moment for me when I started thinking about human nutrition,” he said.

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?

What Loladze found is that scientists simply didn’t know. It was already well documented that CO2levels were rising in the atmosphere, but he was astonished at how little research had been done on how it affected the quality of the plants we eat. For the next 17 years, as he pursued his math career, Loladze scoured the scientific literature for any studies and data he could find. The results, as he collected them, all seemed to point in the same direction: The junk-food effect he had learned about in that Arizona lab also appeared to be occurring in fields and forests around the world. “Every leaf and every grass blade on earth makes more and more sugars as CO2 levels keep rising,” Loladze said. “We are witnessing the greatest injection of carbohydrates into the biosphere in human history―[an] injection that dilutes other nutrients in our food supply.”

Evidently, agricultural researchers have known for some time that many foods have been getting less nutritious. The mineral, vitamin and protein content of fruits and vegetables has dropped steadily over the past 50 years. Researchers had attributed the drop to the fact that farmers have been breeding crops for higher yields, rather than nutrition–that the “significant” decline in everything from protein to calcium, iron and vitamin C could mostly be explained by the varieties farmers were choosing to grow.

More recent research suggests otherwise.

Across nearly 130 varieties of plants and more than 15,000 samples collected from experiments over the past three decades, the overall concentration of minerals like calcium, magnesium, potassium, zinc and iron had dropped by 8 percent on average. The ratio of carbohydrates to minerals was going up. The plants, like the algae, were becoming junk food.

Even climate change deniers concede that CO2 levels have risen. Plants require CO2, so the assumption has been that these higher levels were actually good for agriculture. The emerging research suggest that at certain levels, CO2 depletes the nutritional value of the crops–which contributes to the obesity epidemic, among other things.

The Politico article is lengthy, but it’s well worth reading. And pondering.