## 3 Results
### Spatial Distribution Characteristics of the Projected Terrestrial GPP Variations  
The spatial distribution of GPP across China in 2060 is significantly influenced by global climate change, as illustrated in Figure 2. In January, the regions experiencing a decrease in GPP are predominantly located in eastern China under the SSP126 scenario and gradually diminish with worsening climate conditions. The proportion of regions with declining GPP drops from 86% under the SSP126 scenario to 53% under the SSP585 scenario. Conversely, areas exhibiting an increase in GPP are primarily found in Yunnan Province and also appear along the southeastern coastal area under the SSP245 scenario. In April, contrasting spatial patterns emerged with decreasing GPP observed in Yunnan Province and increasing GPP observed elsewhere. In July, regions experiencing a decline in GPP are concentrated over the North China Plain (NCP), while significant increases occur over the Tibetan Plateau and southern China. The trend of GPP variation shifts from growth to decline for northeastern China between the SSP126 and SSP585 scenarios. In October, most regions of China witnessed an increase in GPP, accounting for approximately 70% of the study area; however, this does not hold true for southern China under both SSP245 and SSP585 scenarios. The reduction of GPP in southern China during October is consistent with the results projected by a machine learning method [45] and might be caused by the rising VPD in this region as shown in Figure S1 and discussed in Section 3.3 because extremely high VPD inhibits photosynthesis through closing plants' stomata [46].  
Figure 3 depicts the spatial distribution of GPP changes resulting from PER in China. Notably, PER enhances GPP across most regions of China, with increasing areas accounting for at least 77% of the study area, particularly in January and October with the proportion exceeds 90%. The Sichuan Basin (SCB) in southwestern China exhibits a relatively high increase in GPP throughout all seasons under the influence of PER. Additionally, higher GPP-increasing regions cover southern China in January and October, the NCP and northeastern China in July, regions between the Yangtze River and the Yellow River in April, and the Yunnan-Guizhou Plateau (YGP) in October. The main decreasing regions appear over Yunnan Province in April and southern China as well as eastern Inner Mongolia during July.  
In terms of the coupling effect of PER and global climate change (see Table S4 and Figure S1), Yunnan Province emerges as the primary region for GPP increase in January, accounting for 72% of the total GPP increment. However, it becomes the primary region for GPP reduction in April, with a decrease of 58.35 TgC. GPP growth is concentrated in the Hunan, Jiangxi, Heilongjiang, Henan provinces, and Inner Mongolia during this month. In July, the Tibet and Qinghai provinces contribute to over half of the total increase. Most provinces exhibit GPP growth under all SSP scenarios in October, with the highest increases observed in the SCB, Heilongjiang Province, and Inner Mongolia.  
Figure 3: Impact of PER on GPP in gC/m\({}^{2}\). Pie charts indicate the percentage of GPP change areas.  
Figure 2: (**a–p**) Impact of global climate change on GPP. Pie charts indicate the proportions of the region with increasing and decreasing GPP.