Abstract Global changes strongly affect methane (CH 4 ) emissions and uptake. However, it is unclear how CH 4 emissions and uptake across rice paddy fields, uplands, and natural wetlands are affected by global change drivers, including nitrogen (N) addition, elevated carbon dioxide (eCO 2 ), warming (W), and precipitation (P). Here, we collected 1,250 observations of manipulated experiments from 303 publications during 1980–2020, encompassing 1,154 observations of single‐factor experiments and 96 observations of two‐paired experiments, and analyzed the effects of global change drivers on CH 4 emissions and uptake. Results showed CH 4 emissions were stimulated by eCO 2 , W, and increased P (IP). CH 4 uptake was inhibited by N and IP but significantly enhanced by W and decreased P. The combined effects of the four global change drivers significantly inhibited CH 4 uptake (−9[−12, −6] %) and stimulated CH 4 emissions (13[7, 19] %). Two‐factor interactions significantly reduced CH 4 emissions (−15[−27, −1] %) and insignificantly reduced uptake (−10[−19, 0] %). The interactive effects of any two global change drivers were mostly antagonistic. Random forest analysis indicated that the important factors affecting the responses of CH 4 emissions or uptake to different global change drivers varied. The structural equation model confirmed that climate, soil properties, and wetness index consistently played a remarkable role in regulating the responses of CH 4 emissions and uptake to global change drivers. This synthesis highlights an urgent need to consider the individual and interactive effects of multiple global change drivers on CH 4 emissions and uptake for a better understanding of the methane‐climate feedback.
Plain Language Summary In this study, 1,250 observations from manipulated experiments were used to analyze the impact of global changes on methane (CH 4 ) emissions and uptake across different ecosystems. Results showed that CH 4 emissions were stimulated by elevated carbon dioxide concentration, warming, and increased precipitation. CH 4 uptake was inhibited by nitrogen and increased precipitation but significantly enhanced by warming and decreased precipitation. Overall, these global change drivers inhibited CH 4 uptake and stimulated CH 4 emissions. The effects of the two‐factor interactions were mostly antagonistic, reducing CH 4 emissions and uptake. Responses of CH 4 emissions and uptake to these factors varied, depending on the treatment level, nitrogen fertilization type, plant and soil properties, climate factors, and warming method. Climate factors, soil properties, and wetness index consistently played significant roles in regulating the responses of CH 4 fluxes to global change drivers. This synthesis emphasized the importance of considering the individual and interactive effects of multiple global change drivers on CH 4 emissions and uptake for understanding the methane‐climate feedback.
Key Points The overall effects of nitrogen (N) addition, elevated carbon dioxide (eCO 2 ), warming (W), and precipitation (P) changes decreased CH 4 uptake (−9[−12, −6] %) and stimulated CH 4 emissions (13[7, 19] %) All two‐factor interactions (e.g., N + W, N + P and W + eCO 2 ) reduced CH 4 emissions (−15[−27, −1] %) with mostly antagonistic effects The structural equation model identified that climate, soil properties, and wetness index played a remarkable role in these responses of CH 4 emissions and uptake to global change drivers