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As the main solid waste disposal method in China, landfill sites are considerable sources of methane (CH 4 ) and carbon dioxide (CO 2 ). This study characterized the seasonal variation of CH 4 and CO 2 effluxes at a large and well-managed final covered landfill site in China. A three-year monitoring program was conducted. There were two different seasonal variation patterns for hotspot and non-hotspot' CH 4 and CO 2 effluxes. For non-hotspots, the CH 4 and CO 2 effluxes' seasonal variations were mainly affected by the seasonal change of the landfill's cover soil respiration activity, particularly the CH 4 oxidation capability. CH 4 had a higher efflux in winter; in other seasons, the CH 4 efflux fluctuated around 0; the CO 2 effluxes were (1) increased in spring and peaked in summer or early autumn; (2) then, they decreased to a minimum value in late autumn or early winter; and (3) fluctuated with the CH 4 efflux in winter. The CH 4 emissions in winter account for 60.4-84.4% of the all year outputs. For the hotspots', the CH 4 and CO 2 effluxes seasonal variations were mainly determined by the seasonal change of the landfill cover's soil gas permeability. The ratio of CH 4 emissions in winter to the all year outputs range from 17.4 to 68.7%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

The alpine wetlands on the Tibetan Plateau (TP) are ecosystems vulnerable to global climate change. It has been recognized that future climate change may have a significant impact on methane (CH 4 ) emissions from the plateau, while less attention has been paid to predicting temporal and spatial variations in CH 4 emissions from TP natural wetlands. In this study, we used an integrated model framework based on the CH4MOD wetland , TOPMODEL and TEM models to predict CH 4 emissions from potential natural wetlands on the TP under IPCC AR5 scenarios from 2006 to 2100. The model estimates suggest that the mean area-weighted CH 4 fluxes will increase from 4.45 ± 0.42 g m -2  yr -1 in 2006 to 4.79 ± 0.72, 5.99 ± 0.85 and 11.53 ± 1.33 g m -2  yr -1 under 3 Representative Concentration Pathway scenarios (RCP 2.6, RCP 4.5 and RCP 8.5 scenarios), respectively, by 2100. The dominant drivers stimulating CH 4 emissions are air temperature, precipitation and net primary productivity (NPP). Spatially, CH 4 fluxes and emissions showed a decreasing trend from south to north and from east to west. In response to climate change, a total of 0.42 ± 0.06, 0.54 ± 0.09 and 1.01 ± 0.12 Tg yr -1 of CH 4 emissions will be emitted from the TP's potential natural wetlands by the end of this century under the RCP 2.6, RCP 4.5 and RCP 8.5 scenarios, respectively., (Copyright © 2018 Elsevier B.V. All rights reserved.)