Please use this identifier to cite or link to this item:
AuthorsEtiope, G.* 
Milkov, A. V.* 
Derbyshire, E.* 
TitleDid geologic emissions of methane play any role in Quaternary climate change?
Issue Date2008
Series/Report no.1-2 / 61 (2008)
Keywordsclimate change
greenhouse gas emissions
Subject Classification03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases 
AbstractThe “methane-led hypotheses” assume that gas hydrates and marine seeps are the sole geologic factors controlling Quaternary atmospheric and climate changes. Nevertheless, a wider class of geologic sources of methane exist which could have played a role in past climate changes. Beyond offshore seepage, relevant geologic emissions of methane (GEM) are from onshore seepage, including mud volcanism, microseepage and geothermal flux; altogether GEM are the second most important natural source of atmospheric methane at present. The amount of methane entering the atmosphere from onshore GEM seems to prevail on that from offshore seepage. Onshore sources inject a predominantly isotopically heavy (13C-enriched) methane into the atmosphere. They are controlled mainly by endogenic (geodynamic) processes, which induce large-scale gas flow variations over geologic and millennial time scales, and only partially by exogenic (surface) conditions, so that they are not affected by negative feedbacks. The eventual influence on atmospheric methane concentration does not necessarily require catastrophic or abrupt releases, as proposed for the “clathrate gun hypothesis”. Enhanced degassing from these sources could have contributed to the methane trends observed in the ice core records, and could explain the late Quaternary peaks of increased methane concentrations accompanied by the enrichment of isotopically heavy methane, as recently observed. This hypothesis shall be tested by means of robust multidisciplinary studies, mainly based on a series of atmospheric, biologic and geologic proxies.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
Eti-Mil-Der-GPC-2008.pdf703.61 kBAdobe PDFView/Open
Show full item record

Page view(s)

Last Week
Last month
checked on Jul 27, 2017


checked on Jul 27, 2017

Google ScholarTM