TY - JOUR
T1 - Water vapour adjustments and responses differ between climate drivers
AU - Hodnebrog, Oivind
AU - Myhre, Gunnar
AU - Samset, Bjorn H.
AU - Alterskjær, Kari
AU - Andrews, Timothy
AU - Boucher, Olivier
AU - Faluvegi, Gregory
AU - Fläschner, Dagmar
AU - M Forster, Piers
AU - Kasoar, Matthew
AU - Kirkeväg, Alf
AU - Lamarque, Jean Francois
AU - Olivié, Dirk
AU - B Richardson, Thomas
AU - Shawki, Dilshad
AU - Shindell, Drew
AU - P Shine, Keith
AU - Stier, Philip
AU - Takemura, Toshihiko
AU - Voulgarakis, Apostolos
AU - Watson-Parris, Duncan
N1 - Funding Information:
Financial support. This research has been supported by the
Funding Information:
This research has been supported by the Research Council of Norway (grant nos. 229778, 207711, and 229771)
Funding Information:
Acknowledgements. Supercomputer facilities were provided by NOTUR (NCAR-CESM1-CAM4 and NorESM1 simulations), the Climate Simulation Laboratory at NCAR’s Computational and Information Systems Laboratory, sponsored by the National Science Foundation and other agencies (ark:/85065/d7wd3xhc; NCAR-CESM1-CAM5 simulations), the NASA High-End Computing Program through the NASA Center for Climate Simulation at Goddard Space Flight Center (GISS-E2-R simulations), the MONsooN system (HadGEM2/3 simulations), the German Climate Computing Center (DKRZ) in Hamburg (MPI-ESM simulations), the ARCHER UK National Supercomputing Service (ECHAM-HAM simulations), by GENCI at the TGCC under allocation gen2201 (IPSL-CM5A simulations), and the supercomputer system of the National Institute for Environmental Studies, Japan, the Environment Research and Technology Development Fund (S-12-3) of the Ministry of the Environment, Japan (MIROC-SPRINTARS simu- lations). Dirk Olivié and Alf Kirkevåg were also supported through the Nordic Centre of Excellence eSTICC (57001). We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups for producing and making available their model output. For CMIP the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We thank Adriana Bailey for comments and Camilla Stjern for comments on an earlier version of the paper. We further thank the three anonymous reviewers for valuable comments.
Publisher Copyright:
© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
PY - 2019/10/17
Y1 - 2019/10/17
N2 - 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 ĝ1/47% 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±0.7d 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.
AB - 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 ĝ1/47% 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±0.7d 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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U2 - 10.5194/acp-19-12887-2019
DO - 10.5194/acp-19-12887-2019
M3 - Article
AN - SCOPUS:85073709505
VL - 19
SP - 12887
EP - 12899
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
SN - 1680-7316
IS - 20
ER -
