[Illustrations, footnotes and references available in PDF version]
Environmental stresses induced by exposure to pollutants, drought, intense solar radiation and high air or water temperatures generate highly-reactive oxygenated compounds that damage both terrestrial and aquatic plants. Ameliorating these stresses typically involves the production of antioxidant enzymes that scavenge and detoxify the highly-reactive oxygenated compounds. Hence, when stresses are present, concentrations and/or activities of antioxidants in plants are generally observed to be high; and a good question to ask, therefore, is how atmospheric CO2 enrichment impacts this relationship and what the observed results imply. A number of researchers have done just that, and in this summary we highlight what they have learned.