Publication Abstracts

Hodnebrog et al. 2019

Hodnebrog, Ø., G. Myhre, B.H. Samset, K. Alterskjær, T. Andrews, O. Boucher, G. Faluvegi, D. Fläschner, P.M. Forster, M. Kasoar, A. Kirkevåg, J.-F. Lamarque, D. Olivié, T.B. Richardson, D. Shawki, D. Shindell, K.P. Shine, P. Stier, T. Takemura, A. Voulgarakis, and D. Watson-Parris, 2019: Water vapour adjustments and responses differ between climate drivers. Atmos. Chem. Phys., 19, 12887-12899, doi:10.5194/acp-19-12887-2019.

Water vapour in the atmosphere is the source of a major climate feedback mechanism and potential increases in the availability of water vapour could have important consequences for mean and extreme precipitation. Future precipitation changes further depend on how the hydrological cycle responds to different drivers of climate change, such as greenhouse gases and aerosols. Currently, neither the total anthropogenic influence on the hydrological cycle nor that from individual drivers is constrained sufficiently to make solid projections. We investigate how integrated water vapour (IWV) responds to different drivers of climate change. Results from 11 global climate models have been used, based on simulations where CO2`, methane, solar irradiance, black carbon (BC), and sulfate have been perturbed separately. While the global-mean IWV is usually assumed to increase by ∼7% per Kelvin of surface temperature change, we find that the feedback response of IWV differs somewhat between drivers. Fast responses, which include the initial radiative effect and rapid adjustments to an external forcing, amplify these differences. The resulting net changes in IWV range from 6.4±0.9 % K-1 for sulfate to 9.8±2 % K-1 for BC. We further calculate the relationship between global changes in IWV and precipitation, which can be characterized by quantifying changes in atmospheric water vapour lifetime. Global climate models simulate a substantial increase in the lifetime, from 8.2±0.5 to 9.9±0.7 d between 1986-2005 and 2081-2100 under a high-emission scenario, and we discuss to what extent the water vapour lifetime provides additional information compared to analysis of IWV and precipitation separately. We conclude that water vapour lifetime changes are an important indicator of changes in precipitation patterns and that BC is particularly efficient in prolonging the mean time, and therefore likely the distance, between evaporation and precipitation.

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BibTeX Citation

  author={Hodnebrog, Ø. and Myhre, G. and Samset, B. H. and Alterskjær, K. and Andrews, T. and Boucher, O. and Faluvegi, G. and Fläschner, D. and Forster, P. M. and Kasoar, M. and Kirkevåg, A. and Lamarque, J.-F. and Olivié, D. and Richardson, T. B. and Shawki, D. and Shindell, D. and Shine, K. P. and Stier, P. and Takemura, T. and Voulgarakis, A. and Watson-Parris, D.},
  title={Water vapour adjustments and responses differ between climate drivers},
  journal={Atmos. Chem. Phys.},

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RIS Citation

ID  - ho01700t
AU  - Hodnebrog, Ø.
AU  - Myhre, G.
AU  - Samset, B. H.
AU  - Alterskjær, K.
AU  - Andrews, T.
AU  - Boucher, O.
AU  - Faluvegi, G.
AU  - Fläschner, D.
AU  - Forster, P. M.
AU  - Kasoar, M.
AU  - Kirkevåg, A.
AU  - Lamarque, J.-F.
AU  - Olivié, D.
AU  - Richardson, T. B.
AU  - Shawki, D.
AU  - Shindell, D.
AU  - Shine, K. P.
AU  - Stier, P.
AU  - Takemura, T.
AU  - Voulgarakis, A.
AU  - Watson-Parris, D.
PY  - 2019
TI  - Water vapour adjustments and responses differ between climate drivers
JA  - Atmos. Chem. Phys.
VL  - 19
SP  - 12887
EP  - 12899
DO  - 10.5194/acp-19-12887-2019
ER  -

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