Carbon (C) storage allows a plant to support growth whenever there is a temporal asynchrony between supply (source strength) and demand of carbon (sink strength). This asynchrony is strongly influenced by changes in light and temperature.Traditionally, C storage is considered as a passive process that occurs whenever there is an excess of C from photosynthesis compared with the demand of C for metabolism. However, the role of C storage may vary from being a passive overflow to being an active process as a strategy of the plant to buffer climate fluctuations and support long-term growth. Despite numerous experiments that have advanced our knowledge in the role of C storage in plants, the exact mechanisms and the consequences at whole-plant level are still limited. We propose that an active C pool needs to be included in simulation models for a better understanding of plant growth patterns under fluctuating environment. The insights gained here are important to optimize crop performance under fluctuating conditions and thus for developing more resource-efficient crop production systems.