Quantifying the irreducible uncertainty in near-term climate projections
If the Paris agreement at the Conference of Parties 21 is implemented very effectively, greenhouse-gas emissions might decrease after year 2020. Whether this would lead to identifiable near-term responses in “iconic” climate quantities of wide scientific and public interest is unclear, because the c...
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ftpubman:oai:pure.mpg.de:item_3003838 2023-08-27T04:08:08+02:00 Quantifying the irreducible uncertainty in near-term climate projections Marotzke, J. 2019-01-24 application/zip application/pdf http://hdl.handle.net/21.11116/0000-0002-5A51-E http://hdl.handle.net/21.11116/0000-0002-708D-1 http://hdl.handle.net/21.11116/0000-0002-B6CF-8 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1002/wcc.563 http://hdl.handle.net/21.11116/0000-0002-5A51-E http://hdl.handle.net/21.11116/0000-0002-708D-1 http://hdl.handle.net/21.11116/0000-0002-B6CF-8 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Wiley Interdisciplinary Reviews - Climate Change info:eu-repo/semantics/article 2019 ftpubman https://doi.org/10.1002/wcc.563 2023-08-02T01:15:04Z If the Paris agreement at the Conference of Parties 21 is implemented very effectively, greenhouse-gas emissions might decrease after year 2020. Whether this would lead to identifiable near-term responses in “iconic” climate quantities of wide scientific and public interest is unclear, because the climate response would be obscured by quasi-random internal variability. I define the climate response as an increase or decrease in a linear climate trend over the period 2021–2035, compared to 2006–2020, and establish the probability of such a trend change being caused by an assumed policy shift toward emissions reductions after 2020. I quantify the irreducible uncertainty in projecting such a trend change through very large (100-member) ensembles of the state-of-the-art climate model MPI-ESM-LR. Trends in global-mean surface temperature (GMST) are higher over the period 2021–2035 than over 2006–2020 in one-third of all realizations in the mitigation scenario RCP2.6, interpreted as implementing the Paris agreement, compared to around one-half in the no-mitigation scenario RCP4.5. Mitigation is sufficient to cause a GMST trend reduction with a probability of 0.40 and necessary with a probability of 0.33. Trend increases in Arctic September sea-ice area and the Atlantic meridional overturning circulation are caused by the emissions reductions with a probability of only around 0.1. By contrast, emissions reductions are necessary for a trend decrease in upper-ocean heat content with a probability of over one-half. Some iconic climate quantities might thus by year 2035 exhibit an identifiable response to a successful Paris agreement but sometimes with low probability, creating a substantial communication challenge. This article is categorized under: Climate Models and Modeling > Knowledge Generation with Models. © 2018 The Authors. WIREs Climate Change published by Wiley Periodicals, Inc. Article in Journal/Newspaper Arctic Climate change Sea ice Max Planck Society: MPG.PuRe Arctic Wiley Interdisciplinary Reviews: Climate Change 10 1 e563 |
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English |
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If the Paris agreement at the Conference of Parties 21 is implemented very effectively, greenhouse-gas emissions might decrease after year 2020. Whether this would lead to identifiable near-term responses in “iconic” climate quantities of wide scientific and public interest is unclear, because the climate response would be obscured by quasi-random internal variability. I define the climate response as an increase or decrease in a linear climate trend over the period 2021–2035, compared to 2006–2020, and establish the probability of such a trend change being caused by an assumed policy shift toward emissions reductions after 2020. I quantify the irreducible uncertainty in projecting such a trend change through very large (100-member) ensembles of the state-of-the-art climate model MPI-ESM-LR. Trends in global-mean surface temperature (GMST) are higher over the period 2021–2035 than over 2006–2020 in one-third of all realizations in the mitigation scenario RCP2.6, interpreted as implementing the Paris agreement, compared to around one-half in the no-mitigation scenario RCP4.5. Mitigation is sufficient to cause a GMST trend reduction with a probability of 0.40 and necessary with a probability of 0.33. Trend increases in Arctic September sea-ice area and the Atlantic meridional overturning circulation are caused by the emissions reductions with a probability of only around 0.1. By contrast, emissions reductions are necessary for a trend decrease in upper-ocean heat content with a probability of over one-half. Some iconic climate quantities might thus by year 2035 exhibit an identifiable response to a successful Paris agreement but sometimes with low probability, creating a substantial communication challenge. This article is categorized under: Climate Models and Modeling > Knowledge Generation with Models. © 2018 The Authors. WIREs Climate Change published by Wiley Periodicals, Inc. |
format |
Article in Journal/Newspaper |
author |
Marotzke, J. |
spellingShingle |
Marotzke, J. Quantifying the irreducible uncertainty in near-term climate projections |
author_facet |
Marotzke, J. |
author_sort |
Marotzke, J. |
title |
Quantifying the irreducible uncertainty in near-term climate projections |
title_short |
Quantifying the irreducible uncertainty in near-term climate projections |
title_full |
Quantifying the irreducible uncertainty in near-term climate projections |
title_fullStr |
Quantifying the irreducible uncertainty in near-term climate projections |
title_full_unstemmed |
Quantifying the irreducible uncertainty in near-term climate projections |
title_sort |
quantifying the irreducible uncertainty in near-term climate projections |
publishDate |
2019 |
url |
http://hdl.handle.net/21.11116/0000-0002-5A51-E http://hdl.handle.net/21.11116/0000-0002-708D-1 http://hdl.handle.net/21.11116/0000-0002-B6CF-8 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Climate change Sea ice |
genre_facet |
Arctic Climate change Sea ice |
op_source |
Wiley Interdisciplinary Reviews - Climate Change |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1002/wcc.563 http://hdl.handle.net/21.11116/0000-0002-5A51-E http://hdl.handle.net/21.11116/0000-0002-708D-1 http://hdl.handle.net/21.11116/0000-0002-B6CF-8 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/wcc.563 |
container_title |
Wiley Interdisciplinary Reviews: Climate Change |
container_volume |
10 |
container_issue |
1 |
container_start_page |
e563 |
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1775348847917137920 |