Vapor pressure deficit dominated the rate of greening and yellowing in the Northern Hemisphere

• RG and RY increased in parallel from 2001 to 2022. • VPD contributed the most to changes in RG and RY. • Direct impact of TMP on RG and RY was offseted by indirect effect of VPD. Variations in vegetation rate of greening (RG) and yellowing (RY) across the Northern Hemisphere (north of 30°N) are crucial to the terrestrial carbon cycle and ecological sustainability. However, previous studies mainly focused on instantaneous phenological phases, lacking a systematic assessment of the changes in RG and RY and their climatic drivers. Using solar-induced chlorophyll fluorescence (CSIF) data from 2001 to 2022, we employs trend analysis, multiple linear regression, and structural equation modeling to investigate the pathways and dominant factors through which temperature (TMP), precipitation (PRE), vapor pressure deficit (VPD), and soil moisture (SM) affect RG and RY. We found that RG and RY increased in parallel from 2001 to 2022, with VPD emerging as the primary driver (29.80 % and 30.06 %, respectively). The proportion dominated by TMP, PRE, VPD, and SM in controlling RG remained relatively stable, whereas VPD’s influence on RY increased significantly (0.175 % yr – 1) and SM’s contribution declined markedly (−0.215 % yr – 1). VPD exerted the strongest direct effects on RG and RY (0.69 and − 0.60), while TMP’s direct impacts on RG and RY were largely offset by VPD’s indirect mediation. Our study offers a scientific foundation to inform the adjustment and formulation of ecological protection policies for terrestrial ecosystems across the Northern Hemisphere.