The decadal response of soil carbon to a changing climate remains uncertain. Radiocarbon measurements of respired CO₂ can provide insights into the actively cycling soil carbon pool. Here we evaluate the extent to which temperature and moisture drive latitudinal differences in the age of respired carbon. We synthesize for the first time heterotrophic respiration data from over 50 incubation studies, which measure the radiocarbon content of the respired CO₂. These measurements are an indicator of the age of carbon leaving the system and correspondingly, the transit time of carbon in soils. The compiled dataset spans a complete latitudinal gradient, from the arctic to the tropics, allowing us to analyze gradients in temperature and precipitation. Additionally, this global dataset provides a valuable tool for constraining rates of active carbon cycling in global models, since models are increasingly providing predictions of the age of respired carbon. To demonstrate this approach, we compare our dataset against the COMISSION model and the E3SM land model (ELM-ECA). An improved representation of the age of respired carbon globally will allow us to better predict the climate response and carbon storage potential of actively cycling soil carbon in the coming decades.