B066-0015
Observation of CH4 emission at the proglacial land surface, Gulkana Glacier, Alaska
Observation of CH4 emission at the proglacial land surface, Gulkana Glacier, Alaska
Friday, 11 December 2020
Poster
Abstract:
Methane is one of the greenhouse gases, and its global warming potential is 25 times of carbon dioxide. Currently, most of the methane emission occurs in low and mid-latitudes, while high-latitude land area is considered to be a potential source of a rapid increase in future emissions. A more accurate estimation of the methane emission is therefore required in the Arctic regions. So far, the water-logged active layer and further thawing of the permafrost have been considered the dominant source of methane emission, and the glacier area has been ignored in the discussion of methane balance. Recently, large emissions of methane were observed in the proglacial area in Greenland and Iceland (e.g., Lamarche-Gagnon et al., 2019). It becomes crucial to verify if the similar methane emissions in the proglacial regions can be found in other glaciers, as it can significantly contribute to the methane balance.
This study aims to verify whether methane emissions could be observed in the proglacial area of a small mountain glacier. We conducted preliminary in-situ measurement of methane flux and the isotope analysis of the air sample at the terminus ground of the Gulkana Glacier in the Alaska Range in mid-July, 2019. The methane flux was measured by the chamber method (Morishita et al., 2015). Slight emissions were observed at seven observation sites, most of which were from wet sediment or in the small pond. The amount of methane export was smaller than the general forest area but more than that in the atmosphere. The reason for small emission can be attributed to that the observation was conducted one month after the start of ground thaw. Our limited measurement showed insignificant methane emissions from the proglacial ground, unlike the observations in Greenland and Iceland; however, the observation in the earlier ground thawing period may display higher emissions. The isotope analysis implies that the origin of methane is geogenic.
This study aims to verify whether methane emissions could be observed in the proglacial area of a small mountain glacier. We conducted preliminary in-situ measurement of methane flux and the isotope analysis of the air sample at the terminus ground of the Gulkana Glacier in the Alaska Range in mid-July, 2019. The methane flux was measured by the chamber method (Morishita et al., 2015). Slight emissions were observed at seven observation sites, most of which were from wet sediment or in the small pond. The amount of methane export was smaller than the general forest area but more than that in the atmosphere. The reason for small emission can be attributed to that the observation was conducted one month after the start of ground thaw. Our limited measurement showed insignificant methane emissions from the proglacial ground, unlike the observations in Greenland and Iceland; however, the observation in the earlier ground thawing period may display higher emissions. The isotope analysis implies that the origin of methane is geogenic.