Abstract Variability in climate exerts a strong influence on vegetation productivity (gross primary productivity; GPP), and therefore has a large impact on the land carbon sink. However, no direct observations of global GPP exist, and estimates rely on models that are constrained by observations at various spatial and temporal scales. Here, we assess the consistency in GPP from global products which extend for more than three decades; two observation‐based approaches, the upscaling of FLUXNET site observations (FLUXCOM) and a remote sensing derived light use efficiency model (RS‐LUE), and from a suite of terrestrial biosphere models (TRENDYv6). At local scales, we find high correlations in annual GPP among the products, with exceptions in tropical and high northern latitudes. On longer time scales, the products agree on the direction of trends over 58% of the land, with large increases across northern latitudes driven by warming trends. Further, tropical regions exhibit the largest interannual variability in GPP, with both rainforests and savannas contributing substantially. Variability in savanna GPP is likely predominantly driven by water availability, although temperature could play a role via soil moisture‐atmosphere feedbacks. There is, however, no consensus on the magnitude and driver of variability of tropical forests, which suggest uncertainties in process representations and underlying observations remain. These results emphasize the need for more direct long‐term observations of GPP along with an extension of in situ networks in underrepresented regions (e.g., tropical forests). Such capabilities would support efforts to better validate relevant processes in models, to more accurately estimate GPP.

中文翻译：

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基于三种全球产品的近几十年来气候驱动的植物生产力变化和趋势


摘要 气候变化对植被生产力（总初级生产力；GPP）影响较大，进而对土地碳汇产生较大影响。然而，不存在对全球 GPP 的直接观测，并且估计依赖于受不同空间和时间尺度观测结果约束的模型。在这里，我们评估全球产品的GPP一致性，这些产品延续了三十多年；两种基于观测的方法，FLUXNET现场观测的升级（FLUXCOM）和遥感衍生的光利用效率模型（RS-LUE），以及一套陆地生物圈模型（TRENDYv6）。在局部范围内，我们发现产品之间的年度 GPP 具有高度相关性，但热带和北高纬度地区除外。在更长的时间尺度上，这些产品对超过 58% 的土地的趋势方向一致，在变暖趋势的推动下，北纬地区的趋势大幅增加。此外，热带地区的 GPP 表现出最大的年际变化，雨林和稀树草原的贡献都很大。稀树草原 GPP 的变异可能主要由可用水量驱动，尽管温度可能通过土壤湿度-大气反馈发挥作用。然而，对于热带森林变异的程度和驱动因素尚未达成共识，这表明过程表示和基本观察仍然存在不确定性。这些结果强调需要对 GPP 进行更直接的长期观测，并在代表性不足的地区（例如热带森林）扩展原位网络。这些功能将支持更好地验证模型中的相关过程，更准确地估计 GPP。