Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade
The growth rate of atmospheric CO _2 on inter-annual time scales is largely controlled by the response of the land and ocean carbon sinks to climate variability. Therefore, the effect of CO _2 emission reductions to achieve the Paris Agreement on atmospheric CO _2 concentrations may be disguised by...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2020-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/abc443 |
| _version_ | 1797747718434586624 |
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| author | Aaron Spring Tatiana Ilyina Jochem Marotzke |
| author_facet | Aaron Spring Tatiana Ilyina Jochem Marotzke |
| author_sort | Aaron Spring |
| collection | DOAJ |
| description | The growth rate of atmospheric CO _2 on inter-annual time scales is largely controlled by the response of the land and ocean carbon sinks to climate variability. Therefore, the effect of CO _2 emission reductions to achieve the Paris Agreement on atmospheric CO _2 concentrations may be disguised by internal variability, and the attribution of a reduction in atmospheric CO _2 growth rate to CO _2 emission reductions induced by a policy change is unclear for the near term. We use 100 single-model simulations and interpret CO _2 emission reductions starting in 2020 as a policy change from scenario Representative Concentration Pathway (RCP) 4.5 to 2.6 in a comprehensive causal theory framework. Five-year CO _2 concentration trends grow stronger in 2021–2025 after CO _2 emission reductions than over 2016–2020 in 30% of all realizations in RCP2.6 compared to 52% in RCP4.5 without CO _2 emission reductions. This implies that CO _2 emission reductions are sufficient by 42%, necessary by 31% and both necessary and sufficient by 22% to cause reduced atmospheric CO _2 trends. In the near term, these probabilities are far from certain. Certainty implying sufficient or necessary causation is only reached after, respectively, ten and sixteen years. Assessments of the efficacy of CO _2 emission reductions in the near term are incomplete without quantitatively considering internal variability. |
| first_indexed | 2024-03-12T15:54:40Z |
| format | Article |
| id | doaj.art-55d71a6fcfa348ccbda387fc53ac1d9b |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T15:54:40Z |
| publishDate | 2020-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-55d71a6fcfa348ccbda387fc53ac1d9b2023-08-09T14:58:42ZengIOP PublishingEnvironmental Research Letters1748-93262020-01-01151111405810.1088/1748-9326/abc443Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decadeAaron Spring0https://orcid.org/0000-0003-0216-2241Tatiana Ilyina1https://orcid.org/0000-0002-3475-4842Jochem Marotzke2https://orcid.org/0000-0001-9857-9900Max Planck Institute for Meteorology , Hamburg, Germany; International Max Planck Research School of Earth System Modelling, IMPRS , Hamburg, GermanyMax Planck Institute for Meteorology , Hamburg, GermanyMax Planck Institute for Meteorology , Hamburg, GermanyThe growth rate of atmospheric CO _2 on inter-annual time scales is largely controlled by the response of the land and ocean carbon sinks to climate variability. Therefore, the effect of CO _2 emission reductions to achieve the Paris Agreement on atmospheric CO _2 concentrations may be disguised by internal variability, and the attribution of a reduction in atmospheric CO _2 growth rate to CO _2 emission reductions induced by a policy change is unclear for the near term. We use 100 single-model simulations and interpret CO _2 emission reductions starting in 2020 as a policy change from scenario Representative Concentration Pathway (RCP) 4.5 to 2.6 in a comprehensive causal theory framework. Five-year CO _2 concentration trends grow stronger in 2021–2025 after CO _2 emission reductions than over 2016–2020 in 30% of all realizations in RCP2.6 compared to 52% in RCP4.5 without CO _2 emission reductions. This implies that CO _2 emission reductions are sufficient by 42%, necessary by 31% and both necessary and sufficient by 22% to cause reduced atmospheric CO _2 trends. In the near term, these probabilities are far from certain. Certainty implying sufficient or necessary causation is only reached after, respectively, ten and sixteen years. Assessments of the efficacy of CO _2 emission reductions in the near term are incomplete without quantitatively considering internal variability.https://doi.org/10.1088/1748-9326/abc443internal variabilityatmospheric CO2fossil-fuel emission reductionsclimate policyuncertaintyParis Agreement |
| spellingShingle | Aaron Spring Tatiana Ilyina Jochem Marotzke Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade Environmental Research Letters internal variability atmospheric CO2 fossil-fuel emission reductions climate policy uncertainty Paris Agreement |
| title | Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade |
| title_full | Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade |
| title_fullStr | Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade |
| title_full_unstemmed | Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade |
| title_short | Inherent uncertainty disguises attribution of reduced atmospheric CO2 growth to CO2 emission reductions for up to a decade |
| title_sort | inherent uncertainty disguises attribution of reduced atmospheric co2 growth to co2 emission reductions for up to a decade |
| topic | internal variability atmospheric CO2 fossil-fuel emission reductions climate policy uncertainty Paris Agreement |
| url | https://doi.org/10.1088/1748-9326/abc443 |
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