Organisms often exhibit transgenerational phenotypic changes in response to an increased risk of parasitism or predation. Shifts in global atmospheric composition could modify these phenotypic effects through changes in either nutrient quantity/quality or altered interactions with higher trophic levels. Here we show that future atmospheric conditions alter a natural enemy-induced wing polyphenism in aphids. Winged offspring production by Uroleucon nigrotuberculatum aphids on goldenrod (Solidago canadensis var. scabra) does not differ in enriched CO2 and/or O3 atmospheres. However, proportionally more winged offspring are produced in response to search cues from both coccinellid predators (Coccinella septempunctata) and hymenopteran parasitoids (Aphidius polygonaphis) relative to plants not searched by natural enemies. Moreover, the magnitude of this response differs under enriched CO2 and O3 environments. Aphids produce more winged offspring in response to predators under elevated CO2, but produce more winged offspring in response to parasitoids under elevated O3. Thus, global atmospheric changes influence natural enemy-mediated phenotypic expression, with potentially far-reaching consequences for trophic dynamics. General morphology; Appendages; Nutrition; Diet; Prey; Genetics; Evolution; Variation; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Predators; Abiotic factors; Chemical factors Coccinella septempunctata (Coccinellidae); Insect prey; Uroleucon nigrotuberculatum (Hemiptera); Prey wing polyphenism induction, future atmospheric conditions effects; Gases; Future atmospheric conditions Aphidius polygonaphis (Aphidiidae); Hemipteran hosts; Uroleucon nigrotuberculatum; Host wing polyphenism induction, future atmospheric conditions effects; Gases; Future atmospheric conditions Uroleucon nigrotuberculatum (Aphidoidea); Wings; Phenotype; Future atmospheric conditions effects; Morphological variation; Natural enemy induced wing polyphenism; Hymenopteran parasites; Aphidius polygonaphis; Plant hosts; Solidago canadensis var. scabra; Insect predators; Coccinella septempunctata (Coleoptera); Gases; Future environmental conditions none