Modeling CH 4 Emissions from Natural Wetlands on the Tibetan Plateau over the Past 60 Years: Influence of Climate Change and Wetland Loss

摘要

The natural wetlands of the Tibetan Plateau (TP) are considered to be an important natural source of methane (CH 4 ) to the atmosphere. The long-term variation in CH 4 associated with climate change and wetland loss is still largely unknown. From 1950 to 2010, CH 4 emissions over the TP were analyzed using a model framework that integrates CH4MOD wetland , TOPMODEL, and TEM models. Our simulation revealed a total increase of 15% in CH 4 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 CH 4 fluxes, the total amount of regional CH 4 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 CH 4 fluxes and regional CH 4 emissions showed a decreasing trend from the southeast to the northwest of the study area. Lower CH 4 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 CH 4 emissions by approximately 20%, even though climate change has accelerated the overall CH 4 emission rates over the last six decades.