Figure 22: Summary data from 279 published experiments in which plants of all types were grown under paired stressed (open circles) and unstressed (closed circles) conditions (66). There were 208, 50, and 21 sets at 300, 600, and an average of about 1350 ppm CO2, respectively. The plant mixture in the 279 studies was slightly biased toward plant types that respond less to CO2 fertilization than does the actual global mixture and therefore underestimates the expected global response. CO2 enrichment also allows plants to grow in drier regions, further increasing the expected global response.