Enhanced seasonal CO_2 exchange caused by amplified plant productivity in northern ecosystems, link to model results

Atmospheric monitoring of high northern latitudes (> 40°N) has shown an enhanced seasonal cycle of carbon dioxide (CO2) since the 1960s but the underlying mechanisms are not yet fully understood. The much stronger increase in high latitudes compared to low ones suggests that northern ecosystems are experiencing large changes in vegetation and carbon cycle dynamics. Here we show that the latitudinal gradient of the increasing CO2 amplitude is mainly driven by positive trends in photosynthetic carbon uptake caused by recent climate change and mediated by changing vegetation cover in northern ecosystems. Our results emphasize the importance of climate-vegetation-carbon cycle feedbacks at high latitudes, and indicate that during the last decades photosynthetic carbon uptake has reacted much more strongly to warming than carbon release processes.

自20世纪60年代以来，针对北纬40°以上高纬度地区的大气监测显示，二氧化碳（CO₂）的季节循环显著增强，但其背后的作用机制尚未完全阐明。高纬度地区的二氧化碳浓度增幅远高于低纬度地区，这表明北半球生态系统的植被与碳循环动态正经历剧烈变化。本研究表明，二氧化碳增幅的纬度梯度主要由近期气候变化引发的光合碳吸收正向趋势所驱动，并受北半球生态系统植被覆盖变化的调控。本研究结果凸显了高纬度地区气候-植被-碳循环反馈机制的重要性，并表明近几十年来，光合碳吸收对气候变暖的响应强度远高于碳释放过程。