Increasing partial carbon dioxide pressure (pCO2) and temperature in the world’s seas and oceans might strongly affect the world’s most important primary producers, i.e. microbial phytoplankton. Global climate change results increased inorganic carbon availability, which has been shown to affect phytoplankton host cellular stoichiometry and growth rates. At the same time warming of the ocean leads to stratification of the surface layers and consequently to phytoplankton nutrient (especially phosphorus) limitation, but also to a changed light climate. Changes in such ecologically relevant environmental factors induces physiological changes in phytoplankton, which are likely to affect virus growth characteristics upon infection. However, thus far only a limited number of studies are published and many questions remain unanswered. Here we provide an overview of how elevated pCO2, phosphorus (P), nitrogen (N), and light availability affect algal host-virus interactions. Moreover, we will show examples of how combined changes in these environmental factors interplay, e.g. light level drastically affects the inhibiting effects of P-limitation on viral burst sizes. We furthermore show how viruses themselves influence the response of the host to a changing environment (i.e. lipid remodeling under P-limitation). These studies provide new insights into how virally induced mortality of phytoplankton is affected by the environment in general (e.g. seasonally and with depth), but particularly also in the long term in the future oceans.