Modeling CH4 Emissions from Natural Wetlands on the Tibetan Plateau over the Past 60 Years: Influence of Climate Change and Wetland Loss

The natural wetlands of the Tibetan Plateau (TP) are considered to be an important natural source of methane (CH4) to the atmosphere. The long-term variation in CH4 associated with climate change and wetland loss is still largely unknown. From 1950 to 2010, CH4 emissions over the TP were analyzed using a model framework that integrates CH4MODwetland, TOPMODEL, and TEM models. Our simulation revealed a total increase of 15% in CH4 fluxes, from 6.1 g m ́2 year ́1 to 7.0 g m ́2 year ́1. This change was primarily induced by increases in temperature and precipitation. Although climate change has accelerated CH4 fluxes, the total amount of regional CH4 emissions decreased by approximately 20% (0.06 Tg—i.e., from 0.28 Tg in the 1950s to 0.22 Tg in the 2000s), due to the loss of 1.41 million ha of wetland. Spatially, both CH4 fluxes and regional CH4 emissions showed a decreasing trend from the southeast to the northwest of the study area. Lower CH4 emissions occurred in the northwestern Plateau, while the highest emissions occurred in the eastern edge. Overall, our results highlighted the fact that wetland loss decreased the CH4 emissions by approximately 20%, even though climate change has accelerated the overall CH4 emission rates over the last six decades.