Implication of extreme atmospheric methane concentrations for chemistry-climate connections
| Autor: | Patrick Jöckel, Franziska Winterstein, Fabian Tanalski, Michael Ponater, Martin Dameris |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Ozone
010504 meteorology & atmospheric sciences Atmospheric methane Radiative forcing Atmospheric sciences 01 natural sciences Ozone depletion chemistry.chemical_compound chemistry Atmospheric chemistry Greenhouse gas Ozone layer Environmental science Stratosphere 0105 earth and related environmental sciences |
| DOI: | 10.5194/acp-2019-41 |
| Popis: | Methane (CH4) is the second most important greenhouse gas, which atmospheric concentration is influenced by human activities. In this study, numerical simulations with a chemistry-climate model (CCM) are performed aiming to assess possible consequences of significantly enhanced CH4 concentrations in the Earth's atmosphere for the climate. We analyze experiments with 2xCH4 and 5xCH4 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 hydroxyl radical (OH) abundance and thereby extending the CH4 lifetime as well as the residence time of other chemical pollutants. The region above the tropopause is impacted by a substantial rise in stratospheric water vapor (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 up-welling and stronger meridional transport towards the polar regions. We calculate the net radiative impact (RI) of the 2xCH4 experiment to be 0.69 W/m2 and for the 5xCH4 experiment to be 1.79 W/m2. A substantial part of the RI 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 two/fivefold 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. |
| Databáze: | OpenAIRE |
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