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Implication of strongly increased atmospheric methane concentrations for chemistry–climate connections

Winterstein, Franziska and Tanalski, Fabian and Jöckel, Patrick and Dameris, Martin and Ponater, Michael (2019) Implication of strongly increased atmospheric methane concentrations for chemistry–climate connections. Atmospheric Chemistry and Physics, 19, pp. 7151-7163. Copernicus Publications. doi: 10.5194/acp-19-7151-2019. ISSN 1680-7316.

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Official URL: http://www.atmos-chem-phys.net/19/7151/2019/


Methane (CH4) is the second-most important directly emitted greenhouse gas, the atmospheric concentration of which is influenced by human activities. In this study, numerical simulations with the chemistry–climate model (CCM) EMAC are performed, aiming to assess possible consequences of significantly enhanced CH4 concentrations in the Earth's atmosphere for the climate. We analyse experiments with 2×CH4 and 5×CH4 present-day (2010) mixing ratio and its quasi-instantaneous chemical impact on the atmosphere. The massive increase in CH4 strongly influences the tropospheric chemistry by reducing the OH abundance and thereby extending the CH4 lifetime as well as the residence time of other chemical substances. The region above the tropopause is impacted by a substantial rise in stratospheric water vapour (SWV). The stratospheric ozone (O3) column increases overall, but SWV-induced stratospheric cooling also leads to a enhanced ozone depletion in the Antarctic lower stratosphere. Regional patterns of ozone change are affected by modification of stratospheric dynamics, i.e. increased tropical upwelling and stronger meridional transport towards the polar regions. We calculate the net radiative impact (RI) of the 2×CH4 experiment to be 0.69 W m−2, and for the 5×CH4 experiment to be 1.79 W m−2. A substantial part of the RH is contributed by chemically induced O3 and SWV changes, in line with previous radiative forcing estimates. To our knowledge this is the first numerical study using a CCM with respect to 2- and 5-fold CH4 concentrations and it is therefore an overdue analysis as it emphasizes the impact of possible strong future CH4 emissions on atmospheric chemistry and its feedback on climate.

Item URL in elib:https://elib.dlr.de/128087/
Document Type:Article
Title:Implication of strongly increased atmospheric methane concentrations for chemistry–climate connections
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Winterstein, FranziskaDLR, IPAhttps://orcid.org/0000-0002-2406-4936
Jöckel, PatrickDLR, IPAhttps://orcid.org/0000-0002-8964-1394
Ponater, MichaelDLR, IPAhttps://orcid.org/0000-0002-9771-4733
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.5194/acp-19-7151-2019
Page Range:pp. 7151-7163
Publisher:Copernicus Publications
Keywords:methane, radiative impact, chemistry-climate interaction, stratospheric ozone, stratospheric water vapour
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Transport System
DLR - Research area:Transport
DLR - Program:V VS - Verkehrssystem
DLR - Research theme (Project):V - Transport und Klima
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Ponater, Dr.rer.nat. Michael
Deposited On:28 Jun 2019 11:33
Last Modified:02 Feb 2020 19:59

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