Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation.

Hai Xu,Hai Xu,Hai Xu,Jianghu Lan,Jianghu Lan,Keke Yu,Keke Yu,Keke Yu,Bin Liu,Bin Liu,Yuanda Ye,Enguo Sheng,Yong Liu,Xulong Wang,Xulong Wang,Fengyan Lu,Yuanda Ye,Yuanda Ye,Enguo Sheng,Xiaoke Qiang,Xiaoke Qiang,Peng Cheng,Peng Cheng

doi:10.1038/srep30431

Abstract

Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated ‘peat deposit-lake sediment’ alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles.

Highlights

Ice core records indicate that the global methane concentration varied rapidly and periodically on orbital/suborbital timescales[1,2]
The δ13C values of atmospheric methane in Antarctic ice cores showed large differences between glacial stadial and interstadial periods, which could not be explained by temperature variations; rather, the different values pointed to the possibility that tropical wetland methane emissions could have accounted for a higher fraction during the stadial periods than during the interstadial periods[16,17]
Because most parameters remain relatively constant, whereas the soil temperature, soil water table, as well as soil biological communities are linked to climatic changes, it seems that the factors that influence climatic changes, e.g., the atmospheric circulations, monsoon intensity, etc., should modulate the long term variations in wetlands methane emissions

Summary

Introduction

Ice core records indicate that the global methane concentration varied rapidly and periodically on orbital/suborbital timescales[1,2]. How is the relative contribution of wetlands methane emission from tropical/subtropical zone as compared to those from the northern high hemisphere during the glacial stadial periods (cold phases in glacial times)?

Results

Conclusion