Moderate climate sensitivity due to opposing mixed-phase cloud feedbacks
Abstract Earth’s climate sensitivity quantifies the ultimate change in global mean surface air temperature in response to a doubling of atmospheric CO2 concentrations. Recent assessments estimate that Earth’s climate sensitivity very likely lies between 2.3 °C and 4.7 °C, with the representation of...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-03-01
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| Series: | npj Climate and Atmospheric Science |
| Online Access: | https://doi.org/10.1038/s41612-025-00948-7 |
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| Summary: | Abstract Earth’s climate sensitivity quantifies the ultimate change in global mean surface air temperature in response to a doubling of atmospheric CO2 concentrations. Recent assessments estimate that Earth’s climate sensitivity very likely lies between 2.3 °C and 4.7 °C, with the representation of clouds in climate models accounting for a large portion of its uncertainty. Here, we adjust the climate sensitivity of individual contemporary climate models after using satellite observations to alleviate biases in their representation of mixed-phase clouds. A resulting moderate average climate sensitivity of 3.63 ± 0.98(1σ) °C arises due to opposing responses of clouds. While increasing the proportion of liquid within cold clouds prior to CO2 doubling increases climate sensitivity via transitions from solid to liquid hydrometeors, a strongly opposing increase in reflective cloud cover decreases climate sensitivity. This emphasizes the need to reconsider the role of mixed-phase cloud cover changes in climate sensitivity assessments. |
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| ISSN: | 2397-3722 |