Reconciling conflicting accounts of local radiative feedbacks in climate models
The literature offers conflicting findings about which regions contribute most to increases in the global radiative feedback after a forcing increase. This paper explains the disagreement by discriminating between two common definitions of the local feedback, which use either local temperature or gl...
Published in: | Journal of Climate |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2022
|
Subjects: | |
Online Access: | http://hdl.handle.net/21.11116/0000-0009-D2D1-D http://hdl.handle.net/21.11116/0000-0009-D485-1 http://hdl.handle.net/21.11116/0000-000A-8DD1-B |
id |
ftpubman:oai:pure.mpg.de:item_3363232 |
---|---|
record_format |
openpolar |
spelling |
ftpubman:oai:pure.mpg.de:item_3363232 2023-08-27T04:12:11+02:00 Reconciling conflicting accounts of local radiative feedbacks in climate models Hedemann, C. Mauritsen, T. Jungclaus, J. Marotzke, J. 2022-05-15 application/gzip application/pdf http://hdl.handle.net/21.11116/0000-0009-D2D1-D http://hdl.handle.net/21.11116/0000-0009-D485-1 http://hdl.handle.net/21.11116/0000-000A-8DD1-B eng eng info:eu-repo/grantAgreement/EC/H2020/820829 info:eu-repo/semantics/altIdentifier/doi/10.1175/JCLI-D-21-0513.1 http://hdl.handle.net/21.11116/0000-0009-D2D1-D http://hdl.handle.net/21.11116/0000-0009-D485-1 http://hdl.handle.net/21.11116/0000-000A-8DD1-B info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Journal of Climate info:eu-repo/semantics/article 2022 ftpubman https://doi.org/10.1175/JCLI-D-21-0513.1 2023-08-02T01:45:08Z The literature offers conflicting findings about which regions contribute most to increases in the global radiative feedback after a forcing increase. This paper explains the disagreement by discriminating between two common definitions of the local feedback, which use either local temperature or global temperature as their basis. Although the two definitions of feedback have been previously compared in aquaplanet models with slab oceans, here the definitions are compared for the first time in an atmosphere–ocean general circulation model (MPI-ESM1.2) integrated over four doublings of atmospheric CO2 concentrations. Large differences between the definitions can be seen in all feedbacks, but especially in the temperature and water vapor feedbacks. Differences of up to 10 W m22 K21 over the Southern Ocean can be explained by the pattern of surface warming, which weights the local feedbacks and reduces their contribution to the global mean. This finding is, however, dependent on the resolution of analysis, because the local-temperature definition is mathematically inconsistent across spatial scales. Furthermore, attempts to estimate the effect of “pattern weighting” by separating local feedbacks and warming patterns at the gridcell level fail, because the radiative change in key tropical regions is also determined by tropospheric stability via the global circulation. These findings indicate that studies of regional feedback change are more sensitive to methodological choices than previously thought, and that the tropics most likely dominate regional contributions to global radiative feedback change on decadal to centennial time scales. SIGNIFICANCE STATEMENT: Radiative feedbacks are processes that either intensify or damp global surface warming. We compare two ways to define local radiative feedbacks in a climate model and find that the choice of definition drastically impacts the results. Differences in feedback between the definitions are up to 10 W m22 K21 over the Southern Ocean; by comparison, the estimate of ... Article in Journal/Newspaper Southern Ocean Max Planck Society: MPG.PuRe Southern Ocean Journal of Climate 35 10 3131 3146 |
institution |
Open Polar |
collection |
Max Planck Society: MPG.PuRe |
op_collection_id |
ftpubman |
language |
English |
description |
The literature offers conflicting findings about which regions contribute most to increases in the global radiative feedback after a forcing increase. This paper explains the disagreement by discriminating between two common definitions of the local feedback, which use either local temperature or global temperature as their basis. Although the two definitions of feedback have been previously compared in aquaplanet models with slab oceans, here the definitions are compared for the first time in an atmosphere–ocean general circulation model (MPI-ESM1.2) integrated over four doublings of atmospheric CO2 concentrations. Large differences between the definitions can be seen in all feedbacks, but especially in the temperature and water vapor feedbacks. Differences of up to 10 W m22 K21 over the Southern Ocean can be explained by the pattern of surface warming, which weights the local feedbacks and reduces their contribution to the global mean. This finding is, however, dependent on the resolution of analysis, because the local-temperature definition is mathematically inconsistent across spatial scales. Furthermore, attempts to estimate the effect of “pattern weighting” by separating local feedbacks and warming patterns at the gridcell level fail, because the radiative change in key tropical regions is also determined by tropospheric stability via the global circulation. These findings indicate that studies of regional feedback change are more sensitive to methodological choices than previously thought, and that the tropics most likely dominate regional contributions to global radiative feedback change on decadal to centennial time scales. SIGNIFICANCE STATEMENT: Radiative feedbacks are processes that either intensify or damp global surface warming. We compare two ways to define local radiative feedbacks in a climate model and find that the choice of definition drastically impacts the results. Differences in feedback between the definitions are up to 10 W m22 K21 over the Southern Ocean; by comparison, the estimate of ... |
format |
Article in Journal/Newspaper |
author |
Hedemann, C. Mauritsen, T. Jungclaus, J. Marotzke, J. |
spellingShingle |
Hedemann, C. Mauritsen, T. Jungclaus, J. Marotzke, J. Reconciling conflicting accounts of local radiative feedbacks in climate models |
author_facet |
Hedemann, C. Mauritsen, T. Jungclaus, J. Marotzke, J. |
author_sort |
Hedemann, C. |
title |
Reconciling conflicting accounts of local radiative feedbacks in climate models |
title_short |
Reconciling conflicting accounts of local radiative feedbacks in climate models |
title_full |
Reconciling conflicting accounts of local radiative feedbacks in climate models |
title_fullStr |
Reconciling conflicting accounts of local radiative feedbacks in climate models |
title_full_unstemmed |
Reconciling conflicting accounts of local radiative feedbacks in climate models |
title_sort |
reconciling conflicting accounts of local radiative feedbacks in climate models |
publishDate |
2022 |
url |
http://hdl.handle.net/21.11116/0000-0009-D2D1-D http://hdl.handle.net/21.11116/0000-0009-D485-1 http://hdl.handle.net/21.11116/0000-000A-8DD1-B |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Journal of Climate |
op_relation |
info:eu-repo/grantAgreement/EC/H2020/820829 info:eu-repo/semantics/altIdentifier/doi/10.1175/JCLI-D-21-0513.1 http://hdl.handle.net/21.11116/0000-0009-D2D1-D http://hdl.handle.net/21.11116/0000-0009-D485-1 http://hdl.handle.net/21.11116/0000-000A-8DD1-B |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1175/JCLI-D-21-0513.1 |
container_title |
Journal of Climate |
container_volume |
35 |
container_issue |
10 |
container_start_page |
3131 |
op_container_end_page |
3146 |
_version_ |
1775356039331315712 |