Background and aims <p>The Qinghai-Tibet Plateau, a climate-sensitive alpine region warming at twice the global rate, exhibits pronounced diurnal and seasonal temperature asymmetry, yet its impacts on soil greenhouse gas dynamics remain poorly quantified. The study investigated how diurnal asymmetric warming regulated soil CO₂ and CH₄ fluxes in alpine meadow on the northeastern QTP edge, a critical zone for understanding climate-carbon feedbacks.</p> Methods <p>The open-top chambers were used to simulate asymmetric diurnal warming, and greenhouse gas flux series were observed from 2023 to 2024 using long-sequence monitoring system, and soil microclimate and biogeochemistry properties were investigated based on ecological plots.</p> Results <p>The results indicated that experimental warming the average respiration rate from 3.9 µmol C m^− 2s^− 1 to 5.7 µmol C m^− 2s^− 1 (W1) and 5.4 µmol C m^− 2s^− 1 (W2), and the warming effect of W1 and W2 during the growing season was 54.4% and 26.3%, with 75.9% and 51.0% during non-growing season, and the promoting effect on respiration at daytime was 36.7% and 31.8%, while the effect at nighttime was 25.5% and 22.2%. The ecosystem functioned as a net CH₄ sink, but warming induced dual effects-enhancing CH₄ oxidation by 29.7% during the growing season while increasing emissions by 30% in the non-growing season.</p> Conclusion <p>The findings underscored that diurnal warming asymmetry disproportionately amplifies respiration and altered greenhouse gas dynamics. In the context of accelerating alpine warming, these results emphasized the need to integrate diurnal and seasonal temperature regimes into predictions of terrestrial carbon-climate feedbacks to refine mitigation strategies for vulnerable high-altitude ecosystems.</p>