Viral infections mediate microbial food web controls on the global carbon cycle under warming

Climate warming will likely disrupt the flow of matter and energy within ecosystems, threatening the global carbon balance. Microorganisms are fundamental components of carbon cycling and are thus integral to ecosystem climate responses. However, ecosystem responses to warming are uncertain due to the functional and trophic complexity of microbial food webs. Here, we expose two major black boxes hindering our ability to anticipate ecosystem climate responses: viral infection and predation by microbial predators. We review current knowledge and uncover critical gaps in knowledge about how warming will impact these important top-down controls on the global carbon cycle. Understanding and predicting ecosystem responses to climate change will require disentangling complex direct and indirect responses within microbial food webs.