Intensifying negative asymmetry in gross primary productivity response to precipitation anomalies across the Northern Hemisphere: evidence and drivers - Jiaxuan Chen; Zongsen Wang; Zijun Wang; Yangyang Liu; Tingyi Xue; Zhongming Wen; Haijing Shi; Zhenqian Wang; Ercha Hu; Stephen Sitch; Wenping Yuan (Journal of Hydrology, 2026)