The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models
Experiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface-air-temperature change is nonlinear in Coupled Model Intercomparison Project phase 5 (CMIP5) Atmosphe...
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ftunivreading:oai:centaur.reading.ac.uk:38318 2024-06-23T07:56:43+00:00 The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models Andrews, Timothy Gregory, Jonathan M. Webb, Mark J. 2015-02-04 text https://centaur.reading.ac.uk/38318/ https://centaur.reading.ac.uk/38318/1/AGW_revised.pdf https://centaur.reading.ac.uk/38318/8/jcli-d-14-00545%252E1.pdf en eng American Meteorological Society https://centaur.reading.ac.uk/38318/1/AGW_revised.pdf https://centaur.reading.ac.uk/38318/8/jcli-d-14-00545%252E1.pdf Andrews, T., Gregory, J. M. <https://centaur.reading.ac.uk/view/creators/90000874.html> orcid:0000-0003-1296-8644 and Webb, M. J. (2015) The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models. Journal of Climate, 28 (4). pp. 1630-1648. ISSN 1520-0442 doi: https://doi.org/10.1175/JCLI-D-14-00545.1 <https://doi.org/10.1175/JCLI-D-14-00545.1> Article PeerReviewed 2015 ftunivreading https://doi.org/10.1175/JCLI-D-14-00545.1 2024-06-11T15:02:59Z Experiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface-air-temperature change is nonlinear in Coupled Model Intercomparison Project phase 5 (CMIP5) Atmosphere-Ocean General Circulation Models (AOGCMs). The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving pattern of surface warming. In 23 out of the 27 AOGCMs examined the climate feedback parameter becomes significantly (95% confidence) less negative – i.e. the effective climate sensitivity increases – as time passes. Cloud feedback parameters show the largest changes. In the AOGCM-mean approximately 60% of the change in feedback parameter comes from the topics (30N-30S). An important region involved is the tropical Pacific where the surface warming intensifies in the east after a few decades. The dependence of climate feedbacks on an evolving pattern of surface warming is confirmed using the HadGEM2 and HadCM3 atmosphere GCMs (AGCMs). With monthly evolving sea-surface-temperatures and sea-ice prescribed from its AOGCM counterpart each AGCM reproduces the time-varying feedbacks, but when a fixed pattern of warming is prescribed the radiative response is linear with global temperature change or nearly so. We also demonstrate that the regression and fixed-SST methods for evaluating effective radiative forcing are in principle different, because rapid SST adjustment when CO2 is changed can produce a pattern of surface temperature change with zero global mean but non-zero change in net radiation at the top of the atmosphere (~ -0.5 Wm-2 in HadCM3). Article in Journal/Newspaper Sea ice CentAUR: Central Archive at the University of Reading Pacific Journal of Climate 28 4 1630 1648 |
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CentAUR: Central Archive at the University of Reading |
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English |
description |
Experiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface-air-temperature change is nonlinear in Coupled Model Intercomparison Project phase 5 (CMIP5) Atmosphere-Ocean General Circulation Models (AOGCMs). The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving pattern of surface warming. In 23 out of the 27 AOGCMs examined the climate feedback parameter becomes significantly (95% confidence) less negative – i.e. the effective climate sensitivity increases – as time passes. Cloud feedback parameters show the largest changes. In the AOGCM-mean approximately 60% of the change in feedback parameter comes from the topics (30N-30S). An important region involved is the tropical Pacific where the surface warming intensifies in the east after a few decades. The dependence of climate feedbacks on an evolving pattern of surface warming is confirmed using the HadGEM2 and HadCM3 atmosphere GCMs (AGCMs). With monthly evolving sea-surface-temperatures and sea-ice prescribed from its AOGCM counterpart each AGCM reproduces the time-varying feedbacks, but when a fixed pattern of warming is prescribed the radiative response is linear with global temperature change or nearly so. We also demonstrate that the regression and fixed-SST methods for evaluating effective radiative forcing are in principle different, because rapid SST adjustment when CO2 is changed can produce a pattern of surface temperature change with zero global mean but non-zero change in net radiation at the top of the atmosphere (~ -0.5 Wm-2 in HadCM3). |
format |
Article in Journal/Newspaper |
author |
Andrews, Timothy Gregory, Jonathan M. Webb, Mark J. |
spellingShingle |
Andrews, Timothy Gregory, Jonathan M. Webb, Mark J. The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
author_facet |
Andrews, Timothy Gregory, Jonathan M. Webb, Mark J. |
author_sort |
Andrews, Timothy |
title |
The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
title_short |
The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
title_full |
The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
title_fullStr |
The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
title_full_unstemmed |
The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
title_sort |
dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models |
publisher |
American Meteorological Society |
publishDate |
2015 |
url |
https://centaur.reading.ac.uk/38318/ https://centaur.reading.ac.uk/38318/1/AGW_revised.pdf https://centaur.reading.ac.uk/38318/8/jcli-d-14-00545%252E1.pdf |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
https://centaur.reading.ac.uk/38318/1/AGW_revised.pdf https://centaur.reading.ac.uk/38318/8/jcli-d-14-00545%252E1.pdf Andrews, T., Gregory, J. M. <https://centaur.reading.ac.uk/view/creators/90000874.html> orcid:0000-0003-1296-8644 and Webb, M. J. (2015) The dependence of radiative forcing and feedback on evolving patterns of surface temperature change in climate models. Journal of Climate, 28 (4). pp. 1630-1648. ISSN 1520-0442 doi: https://doi.org/10.1175/JCLI-D-14-00545.1 <https://doi.org/10.1175/JCLI-D-14-00545.1> |
op_doi |
https://doi.org/10.1175/JCLI-D-14-00545.1 |
container_title |
Journal of Climate |
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28 |
container_issue |
4 |
container_start_page |
1630 |
op_container_end_page |
1648 |
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1802650024675377152 |