Past rapid warmings as a constraint on greenhouse-gas climate feedbacks
Abstract There are large uncertainties in the estimation of greenhouse-gas climate feedback. Recent observations do not provide strong constraints because they are short and complicated by human interventions, while model-based estimates differ considerably. Rapid climate changes during the last gla...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2022-08-01
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| Series: | Communications Earth & Environment |
| Online Access: | https://doi.org/10.1038/s43247-022-00536-0 |
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| Summary: | Abstract There are large uncertainties in the estimation of greenhouse-gas climate feedback. Recent observations do not provide strong constraints because they are short and complicated by human interventions, while model-based estimates differ considerably. Rapid climate changes during the last glacial period (Dansgaard-Oeschger events), observed near-globally, were comparable in both rate and magnitude to current and projected 21st century climate warming and therefore provide a relevant constraint on feedback strength. Here we use these events to quantify the centennial-scale feedback strength of CO2, CH4 and N2O by relating global mean temperature changes, simulated by an appropriately forced low-resolution climate model, to the radiative forcing of these greenhouse gases derived from their concentration changes in ice-core records. We derive feedback estimates (95% CI) of 0.155 ± 0.035 W m−2 K−1 for CO2, 0.114 ± 0.013 W m−2 K−1 for CH4 and 0.106 ± 0.026 W m−2 K−1 for N2O. This indicates that much lower or higher estimates, particularly some previously published values for CO2, are unrealistic. |
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| ISSN: | 2662-4435 |