Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported
The last-generation CMIP6 global circulation models (GCMs) are currently used to interpret past and future climatic changes and to guide policymakers, but they are very different from each other; for example, their equilibrium climate sensitivity (ECS) varies from 1.83 to 5.67 °C (IPCC AR6, 2021). E...
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ftunivnapoliiris:oai:www.iris.unina.it:11588/861919 2024-06-23T07:50:53+00:00 Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported Scafetta, Nicola Scafetta, Nicola 2021 http://hdl.handle.net/11588/861919 https://doi.org/10.3390/cli9110161 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000725386600001 volume:9 issue:11 firstpage:161 numberofpages:30 journal:CLIMATE http://hdl.handle.net/11588/861919 doi:10.3390/cli9110161 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85118936054 https://doi.org/10.3390/cli9110161 CMIP6 climate model temperature record equilibrium climate sensitivity global warming validation and testing info:eu-repo/semantics/article 2021 ftunivnapoliiris https://doi.org/10.3390/cli9110161 2024-06-10T14:58:52Z The last-generation CMIP6 global circulation models (GCMs) are currently used to interpret past and future climatic changes and to guide policymakers, but they are very different from each other; for example, their equilibrium climate sensitivity (ECS) varies from 1.83 to 5.67 °C (IPCC AR6, 2021). Even assuming that some of them are sufficiently reliable for scenario forecasts, such a large ECS uncertainty requires a pre-selection of the most reliable models. Herein the performance of 38 CMIP6 models are tested in reproducing the surface temperature changes observed from 1980–1990 to 2011–2021 in three temperature records: ERA5-T2m, ERA5-850mb, and UAH MSU v6.0 Tlt. Alternative temperature records are briefly discussed but found to be not appropriate for the present analysis because they miss data over large regions. Significant issues emerge: (1) most GCMs overestimate the warming observed during the last 40 years; (2) there is great variability among the models in reconstructing the climatic changes observed in the Arctic; (3) the ocean temperature is usually overestimated more than the land one; (4) in the latitude bands 40° N–70° N and 50° S–70° S (which lay at the intersection between the Ferrel and the polar atmospheric cells) the CMIP6 GCMs overestimate the warming; (5) similar discrepancies are present in the east-equatorial pacific region (which regulates the ENSO) and in other regions where cooling trends are observed. Finally, the percentage of the world surface where the (positive or negative) model-data discrepancy exceeds 0.2, 0.5 and 1.0 °C is evaluated. The results indicate that the models with low ECS values (for example, 3 °C or less) perform significantly better than those with larger ECS. Therefore, the low ECS models should be preferred for climate change scenario forecasts while the other models should be dismissed and not used by policymakers. In any case, significant model-data discrepancies are still observed over extended world regions for all models: on average, the GCM predictions ... Article in Journal/Newspaper Arctic Climate change Global warming IRIS Università degli Studi di Napoli Federico II Arctic Pacific Climate 9 11 161 |
institution |
Open Polar |
collection |
IRIS Università degli Studi di Napoli Federico II |
op_collection_id |
ftunivnapoliiris |
language |
English |
topic |
CMIP6 climate model temperature record equilibrium climate sensitivity global warming validation and testing |
spellingShingle |
CMIP6 climate model temperature record equilibrium climate sensitivity global warming validation and testing Scafetta, Nicola Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
topic_facet |
CMIP6 climate model temperature record equilibrium climate sensitivity global warming validation and testing |
description |
The last-generation CMIP6 global circulation models (GCMs) are currently used to interpret past and future climatic changes and to guide policymakers, but they are very different from each other; for example, their equilibrium climate sensitivity (ECS) varies from 1.83 to 5.67 °C (IPCC AR6, 2021). Even assuming that some of them are sufficiently reliable for scenario forecasts, such a large ECS uncertainty requires a pre-selection of the most reliable models. Herein the performance of 38 CMIP6 models are tested in reproducing the surface temperature changes observed from 1980–1990 to 2011–2021 in three temperature records: ERA5-T2m, ERA5-850mb, and UAH MSU v6.0 Tlt. Alternative temperature records are briefly discussed but found to be not appropriate for the present analysis because they miss data over large regions. Significant issues emerge: (1) most GCMs overestimate the warming observed during the last 40 years; (2) there is great variability among the models in reconstructing the climatic changes observed in the Arctic; (3) the ocean temperature is usually overestimated more than the land one; (4) in the latitude bands 40° N–70° N and 50° S–70° S (which lay at the intersection between the Ferrel and the polar atmospheric cells) the CMIP6 GCMs overestimate the warming; (5) similar discrepancies are present in the east-equatorial pacific region (which regulates the ENSO) and in other regions where cooling trends are observed. Finally, the percentage of the world surface where the (positive or negative) model-data discrepancy exceeds 0.2, 0.5 and 1.0 °C is evaluated. The results indicate that the models with low ECS values (for example, 3 °C or less) perform significantly better than those with larger ECS. Therefore, the low ECS models should be preferred for climate change scenario forecasts while the other models should be dismissed and not used by policymakers. In any case, significant model-data discrepancies are still observed over extended world regions for all models: on average, the GCM predictions ... |
author2 |
Scafetta, Nicola |
format |
Article in Journal/Newspaper |
author |
Scafetta, Nicola |
author_facet |
Scafetta, Nicola |
author_sort |
Scafetta, Nicola |
title |
Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
title_short |
Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
title_full |
Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
title_fullStr |
Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
title_full_unstemmed |
Testing the CMIP6 GCM Simulations versus Surface Temperature Records from 1980–1990 to 2011–2021: High ECS Is Not Supported |
title_sort |
testing the cmip6 gcm simulations versus surface temperature records from 1980–1990 to 2011–2021: high ecs is not supported |
publishDate |
2021 |
url |
http://hdl.handle.net/11588/861919 https://doi.org/10.3390/cli9110161 |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic Climate change Global warming |
genre_facet |
Arctic Climate change Global warming |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000725386600001 volume:9 issue:11 firstpage:161 numberofpages:30 journal:CLIMATE http://hdl.handle.net/11588/861919 doi:10.3390/cli9110161 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85118936054 https://doi.org/10.3390/cli9110161 |
op_doi |
https://doi.org/10.3390/cli9110161 |
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Climate |
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9 |
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11 |
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161 |
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