Carbon emissions from fires in savannas and forests play a key role in the global carbon cycle. As climates change and fires become more frequent and intense, it will be critical to understand what factors determine the resilience of ecosystems to fire. Here, I will present work from tropical savannas in Africa and South America that tests how fire changes ecosystem carbon storage, and the role that climate, nutrients, and plant traits play in mediating the response of savannas to fire. By sampling fire manipulation experiments that have been ongoing for half a century, I found that fire depleted carbon and nutrient pools in soils and vegetation, but that the degree of the effect and the regulating mechanisms depended on climate. The fire-driven nutrient losses filtered the plant community towards more nutrient conservative slow-growing species, suggesting nutrient limitation may limit the recovery of vegetation. Along similar lines, particular plant traits regulated whether species could avoid mortality during fire and were significant determinants of carbon losses at the landscape scale. These results raise new questions about how nutrient losses may limit carbon sequestration, and whether the distribution of plant functional traits can be used to predict resilience across different ecosystems, which I will discuss in the context of my current and future work.