Assessing the impacts of urban expansion and climate change on net primary productivity over the past three decades in Beijing, China

Urban expansion and climate change have profoundly affected terrestrial net primary production (NPP), but their relative contributions to NPP changes across varied stages of urban development remain unclear. Furthermore, many studies were conducted at a low resolution (250–1000 m), which may increase the uncertainty of NPP estimates due to mixed pixels. This study used improved multisource data synergized quantitative (MuSyQ) NPP model to estimate NPP in Beijing during 1990–2020 at a 30 meters (m) resolution, and quantified the effects induced by urban expansion and climate change across different urban expansion stages and functional zones. The urban area in Beijing increased by 1823.91 km² over the study period, the fastest expansion rate occurred between 2000 and 2013, resulting in great NPP loss (18.21 GgCyear⁻¹) (1 Gg = 10⁹ g). The increasingly severe climate change has also led to a reduction in NPP, but this impact is much smaller than the direct loss of NPP caused by urban expansion. Especially between 2000 and 2013, the average annual NPP loss attributed to urban expansion is approximately 22.66 times greater than that caused by climate change. Our findings highlight the urgent need to develop regional strategies to address urban expansion, enhance natural carbon sinks, and achieve sustainable development.