Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 13067-13080, 2016
https://doi.org/10.5194/acp-16-13067-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
21 Oct 2016
The role of methane in projections of 21st century stratospheric water vapour
Laura E. Revell1,2, Andrea Stenke2, Eugene Rozanov2,3, William Ball2,3, Stefan Lossow4, and Thomas Peter2 1Bodeker Scientific, Christchurch, New Zealand
2Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
3Physical-Meteorological Observatory/World Radiation Center, Davos, Switzerland
4Karlsruhe Institute of Technology, Karlsruhe, Germany
Abstract. Stratospheric water vapour (SWV) is an important component of the Earth's atmosphere as it affects both radiative balance and the chemistry of the atmosphere. Key processes driving changes in SWV include dehydration of air masses transiting the cold-point tropopause (CPT) and methane oxidation. We use a chemistry–climate model to simulate changes in SWV through the 21st century following the four canonical representative concentration pathways (RCPs). Furthermore, we quantify the contribution that methane oxidation makes to SWV following each of the RCPs. Although the methane contribution to SWV maximizes in the upper stratosphere, modelled SWV trends are found to be driven predominantly by warming of the CPT rather than by increasing methane oxidation. SWV changes by −5 to 60 % (depending on the location in the atmosphere and emissions scenario) and increases in the lower stratosphere in all RCPs through the 21st century. Because the lower stratosphere is where water vapour radiative forcing maximizes, SWV's influence on surface climate is also expected to increase through the 21st century.

Citation: Revell, L. E., Stenke, A., Rozanov, E., Ball, W., Lossow, S., and Peter, T.: The role of methane in projections of 21st century stratospheric water vapour, Atmos. Chem. Phys., 16, 13067-13080, https://doi.org/10.5194/acp-16-13067-2016, 2016.
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Short summary
Water vapour in the stratosphere plays an important role in atmospheric chemistry and the Earth's radiative balance. We have analysed trends in stratospheric water vapour through the 21st century as simulated by a coupled chemistry–climate model following a range of greenhouse gas emission scenarios. We have also quantified the contribution that methane oxidation in the stratosphere makes to projected water vapour trends.
Water vapour in the stratosphere plays an important role in atmospheric chemistry and the...
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