Emergent constraints on Earth’s transient and equilibrium response to doubled CO2 from post-1970s global warming
Jiménez-de-la-Cuesta, D.; Mauritsen, T. (2019). Emergent constraints on Earth’s transient and equilibrium response to doubled CO2 from post-1970s global warming. Nature Geoscience 12(11): 902-905. https://dx.doi.org/10.1038/s41561-019-0463-y
In: Nature Geoscience. Nature Publishing Group: London. ISSN 1752-0894; e-ISSN 1752-0908, more
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| Authors | | Top |
- Jiménez-de-la-Cuesta, D.
- Mauritsen, T.
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| Abstract |
Future global warming is determined by both greenhouse gas emission pathways and Earth’s transient and equilibrium climate response to doubled atmospheric CO2. Energy-balance inference from the instrumental record typically yields central estimates for the transient response of around 1.3 K and the equilibrium response of 1.5–2.0 K, which is at the lower end of those from contemporary climate models. Uncertainty arises primarily from poorly known aerosol-induced cooling since the early industrialization era and a temporary cooling induced by evolving sea surface temperature patterns. Here we present an emergent constraint on post-1970s warming, taking advantage of the weakly varying aerosol cooling during this period. We derive a relationship between the transient response and the post-1970s warming in Coupled Model Intercomparison Project Phase 5 (CMIP5) models. We thereby constrain, with the observations, the transient response to 1.67 K (1.17–2.16 K, 5–95th percentiles). This is a 20% increase relative to energy-balance inference stemming from previously neglected upper-ocean energy storage. For the equilibrium climate sensitivity we obtain a best estimate of 2.83 K (1.72–4.12 K) contingent on the temporary pattern effects exhibited by climate models. If the real world’s surface temperature pattern effects are substantially stronger, then the upper-bound equilibrium sensitivity may be higher than found here. |
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