Low clouds link equilibrium climate sensitivity to hydrological sensitivity
- 著者
- Watanabe M., Kamae Y., Shiogama H., DeAngelis A. M., Suzuki K.
- 雑誌名
- Nature Climate Change
- DOI
- 10.1038/s41558-018-0272-0
- 概要
-
Equilibrium climate sensitivity (ECS) and hydrological sensitivity describe the global mean surface temperature and precipitation responses to a doubling of atmospheric CO2. Despite their connection via the Earth’s energy budget, the physical linkage between these two metrics remains controversial. Here, using a global climate model with a perturbed mean hydrological cycle, we show that ECS and hydrological sensitivity per unit warming are anti-correlated owing to the low-cloud response to surface warming. When the amount of low clouds decreases, ECS is enhanced through reductions in the reflection of shortwave radiation. In contrast, hydrological sensitivity is suppressed through weakening of atmospheric longwave cooling, necessitating weakened condensational heating by precipitation. These compensating cloud effects are also robustly found in a multi-model ensemble, and further constrained using satellite observations. Our estimates, combined with an existing constraint to clear-sky shortwave absorption, suggest that hydrological sensitivity could be lower by 30% than raw estimates from global climate models.
この論文は2018年9月18日にプレスリリースされました。詳細は、https://www.nies.go.jp/whatsnew/20180914-2/20180914-2.htmlを参照して下さい。