Human-induced westerly jet shifts coordinate terrestrial productivity at the hemispheric scale

Previous studies have established how regional climate variability regulates local terrestrial gross primary productivity (GPP), yet the hemispheric-scale spatial organization of GPP, coordinated by large-scale atmospheric circulation, remains poorly understood. Here, using multi-source observations and numerical simulations, we show that anthropogenic shifts in Northern Hemisphere westerlies fundamentally reorganize terrestrial GPP patterns. Around 2000, westerly curvature reversed from a southward to a northward bend over eastern Europe, Northeast Asia, and western North America, while exhibiting opposite changes over central Asia and central North America. Spatial patterns of GPP trends during 1982-2018 closely match GPP responses to westerly curvature variations. Sensitivity analyses using CESM1 large-ensemble simulations and single-forcing experiments identify greenhouse gas forcing as the dominant driver of these changes, thereby reshaping GPP through surface climatic factors. Under the RCP8.5 scenario, continued curvature changes are projected to enhance GPP growth across northern Europe, Northeast Asia, and western North America, while suppressing productivity in southern Europe and central North America. These results reveal anthropogenic forcing influences terrestrial carbon uptake via large-scale atmospheric circulation, with important implications for predicting future carbon-climate feedback.