Atmospheric methane over the past 2000 years from a sub-tropical ice core,central Himalayas |
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Authors: | Jiule Li Baiqing Xu Tandong Yao Ninglian Wang MacClune Ken |
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Affiliation: | LI Jiule1*,XU Baiqing1,YAO Tandong1,2,WANG Ninglian2,Ken MacClune3 1 Laboratory of Tibetan Environment Changes and Land Surface Processes,Chinese Academy of Sciences,Beijing 100085,China 2 State Key Laboratory of Cryospheric Science,Lanzhou 730000,China 3 Stable Isotope Laboratory,Institute of Arctic and Alpine Research,University of Colorado,Boulder,Colorado,CO 80303,USA |
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Abstract: | A high-resolution 2000-year methane record has been constructed from an ice core recovered at 7200 m a.s.l. on the Dasuopu
Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend in the concentration of methane
during the industrial era that is similar to observations from polar regions. However, we also observed the differences in
the atmospheric methane mixing ratio between this monsoon record and those from polar regions during pre-industrial times.
In the time interval 0 ∼ 1850 A.D., the average methane concentration in the Dasuopu ice core was 782±40 ppbv and the maximum
temporal variation exceeded 200 ppbv. The difference gradient of methane concentration in Dasuopu ice core with Greenland
and Antarctica cores are 66±40 ppbv and 107±40 ppbv, respectively. This suggests that the tropical latitudes might have acted
as a major global methane source in preindustrial times. In addition, the temporal fluctuation of the pre-industrial methane
records suggests that monsoon evolution incorporated with high methane emission from south Asia might be responsible for the
relatively high methane concentration observed in the Dasuopu ice core around A.D. 800 and A.D. 1600. These results provide
a rough understanding of the contribution of tropical methane source to the global methane budget and also the relationship
between atmospheric methane and climate change. |
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Keywords: | climate change ice core air bubble atmospheric methane Dasuopu Glacier central Himalayas |
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