Balancing carbon storage under elevated CO2.

A global synthesis of experiments reveals that increases in plant biomass under conditions of elevated CO2 mean that plants need to mine the soil for nutrients, which decreases soil’s ability to store carbon. In forests, elevated CO2 generally seems to greatly increase plant biomass, but not soil carbon. In grasslands, by contrast, it causes small changes in biomass and large increases in soil carbon. Strategies to maximize carbon uptake by land should account for soil carbon storage.