Tree-ring width serves as a key proxy for assessing environmental change and ontogenetic growth trends. However, dendroecological studies often overlook the effects of ontogenetic stage and the fundamental growth-lifespan trade-off that governs radial growth. This oversight introduces substantial uncertainty into predictions of forest carbon sequestration, particularly in the climate-sensitive region of the Tibetan Plateau, where how this trade-off is modulated by climate and ontogeny remains unclear. Here, tree-ring width datasets from the Tibetan Plateau were exploited to analyze this issue. The results revealed a universal growth-lifespan trade-off, identifying an optimal mean radial growth rate of 0.66 mm/y (lifespan: 614 years; maximum potential radius: 408 mm). This trade-off implies that climate change will primarily alter growth rates rather than ultimate tree size, due to compensatory lifespan adjustments. Under current climate conditions, this optimum occurs at an annual precipitation of 568 mm and a mean annual temperature of 4.40 degrees C. Projections indicate that future global warming will expand the areas where tree radial growth potential is constrained. Furthermore, the trade-off was found to be influenced by climate type and ontogenetic stage. It was steeper in semi-arid regions than in semi-humid regions, and it was further intensified in over-mature stands compared to mature ones. These steeper trade-offs corresponded to heightened climatic sensitivity. Our findings provide new insights into evaluating the effects of climate change on tree growth. In conclusion, integrating the growth-lifespan trade-off and its modulators is essential for accurately assessing the impact of climate change on forest ecosystems.