@AndrewDessler Droughts are WORSE with low CO2. The 1876-78 global drought & famine killed ≈3.7% of world population! Thankfully, elevated CO2 mitigates drought impacts by making plants more drought resilient, thru reduced stomatal conductance.
sealevel.info/learnmore.html…
@AndrewDessler The fact that elevated CO2 makes crops more water-efficient and drought resilient, by reducing stomatal conductance, is well-established. The effect has been measured by many rigorous studies. E.g.
sciencedirect.com/science/articl…
@AndrewDessler That's why thousands of studies have found that under dry conditions elevated CO2 (eCO2) is especially beneficial, for ALL important crops.
eCO2 also beneficial under other conditions, but it is ESPECIALLY beneficial under dry conditions.
@AndrewDessler Periodic droughts have always been a grave threat to many important crops, but eCO2 helps mitigate drought damage. Here's how eCO2 benefits wheat:
ncbi.nlm.nih.gov/pubmed/26929390
@AndrewDessler Sorghum & millet are C4 crops, yet they benefit greatly from eCO2. C4 plants withstand low CO2 levels better than do C3 plants. But agronomists have found that, like C3 crops, C4 crops benefit enormously from extra CO2, in dry conditions.
@AndrewDessler Most crops use the C3 photosynthesis pathway. C3 crops have long been known to benefit greatly from eCO2.
But here's a paper about how eCO2 greatly benefits corn. Like sorghum & millet, corn (maize) is a C4 grain. (It's the most important C4 crop, by far.)
tandfonline.com/doi/abs/10.108…
@AndrewDessler Legumes are grown for their high protein content, and they fix their own nitrogen — a boon where N fertilizer is unavailable or unaffordable. (That's almost everywhere, these days, thanks to restricted natural gas supplies.)
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