%0 Journal Article %1 goldblatt2021earths %A Goldblatt, Colin %A McDonald, Victoria L. %A McCusker, Kelly E. %D 2021 %J Nature Geoscience %K climate-sensitivity equilibrium general %R 10.1038/s41561-021-00691-7 %T Earth’s long-term climate stabilized by clouds %U https://doi.org/10.1038/s41561-021-00691-7 %X The Sun was dimmer earlier in Earth’s history, but glaciation was rare in the Precambrian: this is the ‘faint young Sun problem’. Most solutions rely on changes to the chemical composition of the atmosphere to compensate via a stronger greenhouse effect, whereas physical feedbacks have received less attention. We perform global climate model experiments, using two versions of the Community Atmosphere Model, in which a reduced solar constant is offset by higher CO2. Model runs corresponding to past climate show a substantial decrease in low clouds and hence planetary albedo compared with present, which contributes 40% of the required forcing to offset the faint Sun. Through time, the climatically important stratocumulus decks have grown in response to a brightening Sun and decreasing greenhouse effect, driven by stronger cloud-top radiative cooling (which drives low cloud formation) and a stronger inversion (which sustains clouds against dry air entrainment from above). We find that systematic changes to low clouds have had a major role in stabilizing climate through Earth’s history, which demonstrates the importance of physical feedbacks on long-term climate stabilization, and a smaller role for geochemical feedbacks.

@article{goldblatt2021earths, abstract = {The Sun was dimmer earlier in Earth’s history, but glaciation was rare in the Precambrian: this is the ‘faint young Sun problem’. Most solutions rely on changes to the chemical composition of the atmosphere to compensate via a stronger greenhouse effect, whereas physical feedbacks have received less attention. We perform global climate model experiments, using two versions of the Community Atmosphere Model, in which a reduced solar constant is offset by higher CO2. Model runs corresponding to past climate show a substantial decrease in low clouds and hence planetary albedo compared with present, which contributes 40% of the required forcing to offset the faint Sun. Through time, the climatically important stratocumulus decks have grown in response to a brightening Sun and decreasing greenhouse effect, driven by stronger cloud-top radiative cooling (which drives low cloud formation) and a stronger inversion (which sustains clouds against dry air entrainment from above). We find that systematic changes to low clouds have had a major role in stabilizing climate through Earth’s history, which demonstrates the importance of physical feedbacks on long-term climate stabilization, and a smaller role for geochemical feedbacks.}, added-at = {2021-02-26T11:44:51.000+0100}, author = {Goldblatt, Colin and McDonald, Victoria L. and McCusker, Kelly E.}, biburl = {https://www.bibsonomy.org/bibtex/2ab5229ec6209ab70f2550cf87b06bd87/simon.brown}, description = {Earth’s long-term climate stabilized by clouds | Nature Geoscience}, doi = {10.1038/s41561-021-00691-7}, interhash = {6ba3891b8a634a83a0fcded7b2c17ff4}, intrahash = {ab5229ec6209ab70f2550cf87b06bd87}, issn = {17520908}, journal = {Nature Geoscience}, keywords = {climate-sensitivity equilibrium general}, refid = {Goldblatt2021}, timestamp = {2021-02-26T11:44:51.000+0100}, title = {Earth’s long-term climate stabilized by clouds}, url = {https://doi.org/10.1038/s41561-021-00691-7}, year = 2021 }