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| Titel |
Possible reasons of the enhanced methane emission from the permafrost part of Russia |
| VerfasserIn |
Svetlana Reneva, Julia Strelchenko, Oleg Anisimov, Vasily Kokorev |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072014
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| Zusammenfassung |
| Our last study was focused on researching into the methane emission from Russian frozen
wetlands and evaluation of this effect on global radiative forcing. Results for the
mid-21st century indicate that the annual emission of methane from Russian permafrost
region may increase by 6–8 Mt y-1. Resulting from such an increase additional
radiative forcing may raise the global mean of annual air temperature by 0.012
oC.
In this research we developed a conceptual model explaining enhanced methane emission
at the shelf of the East Siberian Arctic Seas (ESAS). Although observations are infrequent in
time and space, they clearly indicate the presence of strong sources of methane at selected
locations on the ESAS-shelf. Natalia Shakhova with co-authors hypothesized in numerous
publications that enhanced methane emissions are attributed to recent thawing of sub-aquatic
permafrost at ESAS, and predicted catastrophic environmental changes in the nearest future,
which was called the “methane bomb” scenario. We don’t share this point of view. According
their results, the annual methane emission from ESAS is 7,9 Mt. But if we refer to our
research of emission from wetlands, we can see that this amount is not so catastrophic for
global temperature.
So we focused on the concept indicating that observed enhanced fluxes are not related to
recent changes in the subaquatic permafrost but are rather attributed to other mechanisms,
which are yet to be studied. In our primarily opinion those mechanisms are associated with
the geological history of ESAS. The ultimate goal is to combine them into conceptual model
that explains methane observations at ESAS in the context of the past, present, and future
environmental changes.
We shall explore the hypothesis which suggests that observed methane venting is mostly
bound to unfrozen bottom sediments surrounding fault zones and paleo river beds, while
elsewhere on the inner ESAS shelf sediments remain frozen and impermeable for gases since
the last glacial maximum. We checked this hypothesis by collecting published geological and
paleo data, including those on high resolution batimetry, analysing of genesis of
the bottom sediment samples, and constructing the digital high resolution map of
the fault zones and paleo river and lake beds at ESAS, which is compared with
locations of the hydrographic stations where enhanced methane fluxes have been
observed.
Our hypothesis suggests that the methane emission at ESAS is controlled by geological
factors rather than by recent changes in permafrost. This study made a step towards bridging
the gap between the two competing positions of Shakhova’s team and our group, and in the
follow-up discussion we agreed that the analysis of the geological history and paleo data from
bottom sediments is a key to understanding the mechanisms of methane venting at ESAS. |
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