Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions
Abstract The transient climate response to cumulative carbon emissions (TCRE) is a key metric in estimating the remaining carbon budget for given temperature targets. However, the TCRE has a small scenario dependence that can be non-negligible for stringent temperature targets. To investigate the pa...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2020-12-01
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| Series: | Progress in Earth and Planetary Science |
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| Online Access: | https://doi.org/10.1186/s40645-020-00392-6 |
| _version_ | 1831637201139531776 |
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| author | Kaoru Tachiiri |
| author_facet | Kaoru Tachiiri |
| author_sort | Kaoru Tachiiri |
| collection | DOAJ |
| description | Abstract The transient climate response to cumulative carbon emissions (TCRE) is a key metric in estimating the remaining carbon budget for given temperature targets. However, the TCRE has a small scenario dependence that can be non-negligible for stringent temperature targets. To investigate the parametric correlations and scenario dependence of the TCRE, the present study uses a 512-member ensemble of an Earth system model of intermediate complexity (EMIC) perturbing 11 physical and biogeochemical parameters under scenarios with steady increases of 0.25%, 0.5%, 1%, 2%, or 4% per annum (ppa) in the atmospheric CO2 concentration (pCO2), or an initial increase of 1% followed by an annual decrease of 1% thereafter. Although a small difference of 5% (on average) in the TCRE is observed between the 1-ppa and 0.5-ppa scenarios, a significant scenario dependence is found for the other scenarios, with a tendency toward large values in gradual or decline-after-a-peak scenarios and small values in rapidly increasing scenarios. For all scenarios, correlation analysis indicates a remarkably large correlation between the equilibrium climate sensitivity (ECS) and the relative change in the TCRE, which is attributed to the longer response time of the high ECS model. However, the correlations of the ECS with the TCRE and its scenario dependence for scenarios with large pCO2 increase rates are slightly smaller, and those of biogeochemical parameters such as plant respiration and the overall pCO2–carbon cycle feedback are larger, than in scenarios with gradual increases. The ratio of the TCREs under the overshooting (i.e., 1-ppa decrease after a 1-ppa increase) and 1-ppa increase only scenarios had a clear positive relation with zero-emission commitments. Considering the scenario dependence of the TCRE, the remaining carbon budget for the 1.5 °C target could be reduced by 17 or 22% (before and after considering the unrepresented Earth system feedback) for the most extreme case (i.e., the 67th percentile when using the 0.25-ppa scenario as compared to the 1-ppa increase scenario). A single ensemble EMIC is also used to indicate that, at least for high ECS (high percentile) cases, the scenario dependence of the TCRE should be considered when estimating the remaining carbon budget. |
| first_indexed | 2024-12-19T06:47:06Z |
| format | Article |
| id | doaj.art-67ff8b28a2aa48c994cb3a34ea9fc1e9 |
| institution | Directory Open Access Journal |
| issn | 2197-4284 |
| language | English |
| last_indexed | 2024-12-19T06:47:06Z |
| publishDate | 2020-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Progress in Earth and Planetary Science |
| spelling | doaj.art-67ff8b28a2aa48c994cb3a34ea9fc1e92022-12-21T20:31:52ZengSpringerOpenProgress in Earth and Planetary Science2197-42842020-12-017111210.1186/s40645-020-00392-6Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissionsKaoru Tachiiri0Research Center for Environmental Modeling and Application, Research Institute for Global Change, Japan Agency for Marine-Earth Science and TechnologyAbstract The transient climate response to cumulative carbon emissions (TCRE) is a key metric in estimating the remaining carbon budget for given temperature targets. However, the TCRE has a small scenario dependence that can be non-negligible for stringent temperature targets. To investigate the parametric correlations and scenario dependence of the TCRE, the present study uses a 512-member ensemble of an Earth system model of intermediate complexity (EMIC) perturbing 11 physical and biogeochemical parameters under scenarios with steady increases of 0.25%, 0.5%, 1%, 2%, or 4% per annum (ppa) in the atmospheric CO2 concentration (pCO2), or an initial increase of 1% followed by an annual decrease of 1% thereafter. Although a small difference of 5% (on average) in the TCRE is observed between the 1-ppa and 0.5-ppa scenarios, a significant scenario dependence is found for the other scenarios, with a tendency toward large values in gradual or decline-after-a-peak scenarios and small values in rapidly increasing scenarios. For all scenarios, correlation analysis indicates a remarkably large correlation between the equilibrium climate sensitivity (ECS) and the relative change in the TCRE, which is attributed to the longer response time of the high ECS model. However, the correlations of the ECS with the TCRE and its scenario dependence for scenarios with large pCO2 increase rates are slightly smaller, and those of biogeochemical parameters such as plant respiration and the overall pCO2–carbon cycle feedback are larger, than in scenarios with gradual increases. The ratio of the TCREs under the overshooting (i.e., 1-ppa decrease after a 1-ppa increase) and 1-ppa increase only scenarios had a clear positive relation with zero-emission commitments. Considering the scenario dependence of the TCRE, the remaining carbon budget for the 1.5 °C target could be reduced by 17 or 22% (before and after considering the unrepresented Earth system feedback) for the most extreme case (i.e., the 67th percentile when using the 0.25-ppa scenario as compared to the 1-ppa increase scenario). A single ensemble EMIC is also used to indicate that, at least for high ECS (high percentile) cases, the scenario dependence of the TCRE should be considered when estimating the remaining carbon budget.https://doi.org/10.1186/s40645-020-00392-6Transient climate response to cumulative carbon emissionsScenario dependenceEarth system models of intermediate complexityEquilibrium climate sensitivityZero-emission commitmentCarbon budget |
| spellingShingle | Kaoru Tachiiri Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions Progress in Earth and Planetary Science Transient climate response to cumulative carbon emissions Scenario dependence Earth system models of intermediate complexity Equilibrium climate sensitivity Zero-emission commitment Carbon budget |
| title | Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| title_full | Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| title_fullStr | Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| title_full_unstemmed | Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| title_short | Relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| title_sort | relationship between physical and biogeochemical parameters and the scenario dependence of the transient climate response to cumulative carbon emissions |
| topic | Transient climate response to cumulative carbon emissions Scenario dependence Earth system models of intermediate complexity Equilibrium climate sensitivity Zero-emission commitment Carbon budget |
| url | https://doi.org/10.1186/s40645-020-00392-6 |
| work_keys_str_mv | AT kaorutachiiri relationshipbetweenphysicalandbiogeochemicalparametersandthescenariodependenceofthetransientclimateresponsetocumulativecarbonemissions |