How to think about the clear-sky shortwave water vapor feedback

Abstract Earth’s climate feedback quantifies the response of Earth’s energy budget to temperature changes and thus determines climate sensitivity. The climate feedback is largely controlled by water vapor which absorbs both longwave radiation emitted by Earth and shortwave radiation from the Sun. Fo...

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Main Authors: Florian E. Roemer, Stefan A. Buehler, Kaah P. Menang
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:npj Climate and Atmospheric Science
Online Access:https://doi.org/10.1038/s41612-025-01144-3
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author Florian E. Roemer
Stefan A. Buehler
Kaah P. Menang
author_facet Florian E. Roemer
Stefan A. Buehler
Kaah P. Menang
author_sort Florian E. Roemer
collection DOAJ
description Abstract Earth’s climate feedback quantifies the response of Earth’s energy budget to temperature changes and thus determines climate sensitivity. The climate feedback is largely controlled by water vapor which absorbs both longwave radiation emitted by Earth and shortwave radiation from the Sun. For the clear-sky shortwave water vapor feedback λ SW, a gap remains between process understanding and estimates from comprehensive climate models. Therefore, we present a hierarchy of simple models for λ SW. We show that λ SW is proportional to the change with temperature in the square of atmospheric transmissivity that depends on the atmospheric concentration of water vapor and its ability to absorb shortwave radiation. The global mean λ SW is well captured by a simple analytical model that approximates the strong spectral variations in water vapor absorption, whereas its temperature dependence results from spectral details in water vapor absorption. With this study, we expand the conceptual understanding of an important but understudied feedback component.
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issn 2397-3722
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publishDate 2025-07-01
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series npj Climate and Atmospheric Science
spelling doaj-art-014b25ad2858472fb2ffd92ce2e720be2025-08-20T03:42:30ZengNature Portfolionpj Climate and Atmospheric Science2397-37222025-07-018111010.1038/s41612-025-01144-3How to think about the clear-sky shortwave water vapor feedbackFlorian E. Roemer0Stefan A. Buehler1Kaah P. Menang2Center for Earth System Research and Sustainability (CEN), Meteorological Institute, Universität HamburgCenter for Earth System Research and Sustainability (CEN), Meteorological Institute, Universität HamburgCenter for Earth System Research and Sustainability (CEN), Meteorological Institute, Universität HamburgAbstract Earth’s climate feedback quantifies the response of Earth’s energy budget to temperature changes and thus determines climate sensitivity. The climate feedback is largely controlled by water vapor which absorbs both longwave radiation emitted by Earth and shortwave radiation from the Sun. For the clear-sky shortwave water vapor feedback λ SW, a gap remains between process understanding and estimates from comprehensive climate models. Therefore, we present a hierarchy of simple models for λ SW. We show that λ SW is proportional to the change with temperature in the square of atmospheric transmissivity that depends on the atmospheric concentration of water vapor and its ability to absorb shortwave radiation. The global mean λ SW is well captured by a simple analytical model that approximates the strong spectral variations in water vapor absorption, whereas its temperature dependence results from spectral details in water vapor absorption. With this study, we expand the conceptual understanding of an important but understudied feedback component.https://doi.org/10.1038/s41612-025-01144-3
spellingShingle Florian E. Roemer
Stefan A. Buehler
Kaah P. Menang
How to think about the clear-sky shortwave water vapor feedback
npj Climate and Atmospheric Science
title How to think about the clear-sky shortwave water vapor feedback
title_full How to think about the clear-sky shortwave water vapor feedback
title_fullStr How to think about the clear-sky shortwave water vapor feedback
title_full_unstemmed How to think about the clear-sky shortwave water vapor feedback
title_short How to think about the clear-sky shortwave water vapor feedback
title_sort how to think about the clear sky shortwave water vapor feedback
url https://doi.org/10.1038/s41612-025-01144-3
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