Methane emission from tropical/subtropical wetlands contributed about 78% global methane emission from nature wetlands. Decreased wetland CH4 emissions could act as a negative feedback to future climate warming and vice versa. Recent study suggested that powerful warming events in the eastern equatorial region, known as El Niños, are likely to double as greenhouse-gas emissions rise this century. However, the impact of ENSO on wetland emission variability has been paid less attention and remained poorly quantified at both regional and global scales. Here, we used an improved global greenhouse gases dynamic model of TRIPLEX-GHG to investigate the impacts of interannual variations on CH4 emissions in tropical wetlands during the period 1950 to 2012.
Results/Conclusions
Our modeled results suggest that CH4 emissions from tropical wetlands respond strongly, with larger negative anomalies during El Niño years and larger positive anomalies in La Niña years, to repeated ENSO events throughout 1950s- 2000s, which has probably contributed to the recent decrease in the atmospheric growth rate of CH4 concentration during 1980s-1990s and stabilized observed atmospheric CH4 concentrations during 1999-2006.