Biological N₂ fixation sustains the global inventory of nitrogenous nutrients essential for the productivity of terrestrial and marine ecosystems. Like most metabolic processes, rates of biological N₂ fixation vary strongly with temperature, making it sensitive to climate change, but a global projection across land and ocean is lacking. Here we use compilations of field and laboratory measurements to reveal a relationship between N₂ fixation rates and temperature that is similar in both domains despite large taxonomic and environmental differences. Rates of N₂ fixation increase gradually to a thermal optimum around ~25°C, and decline more rapidly toward a thermal maximum, which is lower in the ocean than on land. In both realms, the observed temperature sensitivities imply that climate warming this century could decrease N₂ fixation rates by ~50% in the tropics while increasing rates by ~50% in higher latitudes. We propose a conceptual framework for understanding the physiological and ecological mechanisms that underpin and modulate the observed temperature dependence of global N₂ fixation rates, facilitating cross-fertilization of marine and terrestrial research to assess its response to climate change.

生物 N ₂固定维持了陆地和海洋生态系统生产力所必需的全球氮养分库存。与大多数代谢过程一样，生物 N ₂固定速率随温度变化很大，使其对气候变化敏感，但缺乏跨陆地和海洋的全球预测。_{在这里，我们使用现场和实验室测量的汇编来揭示 N 2}固定率和温度之间的关系，尽管分类学和环境差异很大，但在两个领域中该关系相似。_{N 2}固定速率逐渐增加至约 25°C 左右的热最佳值，并更快地下降至热最大值，海洋中的热最大值低于陆地上的热最大值。在这两个领域，观测到的温度敏感性表明，本世纪气候变暖可能会使热带地区的N _{2固定率降低约 50%，而在高纬度地区，N 2 固定率会增加约 50%。}我们提出了一个概念框架，用于理解支撑和调节观察到的全球 N ₂固定率的温度依赖性的生理和生态机制，促进海洋和陆地研究的交叉融合，以评估其对气候变化的响应。