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Mid-Pleistocene transition in glacial cycles explained by declining CO2 and regolith removal (2019)

Willeit, M., Ganopolski, A., Calov, R., Brovkin, V.

American Association for the Advancement of Science (AAAS)

In: Science Advances

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Publikationsdatum: 2019

Beschreibung: 〈p〉Variations in Earth’s orbit pace the glacial-interglacial cycles of the Quaternary, but the mechanisms that transform regional and seasonal variations in solar insolation into glacial-interglacial cycles are still elusive. Here, we present transient simulations of coevolution of climate, ice sheets, and carbon cycle over the past 3 million years. We show that a gradual lowering of atmospheric CO〈sub〉2〈/sub〉 and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO〈sub〉2〈/sub〉 decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO〈sub〉2〈/sub〉 decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO〈sub〉2〈/sub〉 concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.〈/p〉

Digitale ISSN: 2375-2548

Thema: Allgemeine Naturwissenschaft

Publiziert von American Association for the Advancement of Science (AAAS)

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Nonlinear climate sensitivity and its implications for future greenhouse warming (2016)

Friedrich, T., Timmermann, A., Tigchelaar, M., Elison Timm, O., Ganopolski, A.

American Association for the Advancement of Science (AAAS)

In: Science Advances

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Publikationsdatum: 2016-11-11

Beschreibung: Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity ( S )—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth’s future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections.

Digitale ISSN: 2375-2548

Thema: Allgemeine Naturwissenschaft

Publiziert von American Association for the Advancement of Science (AAAS)

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Mid-Pleistocene transition in glacial cycles explained by declining CO2and regolith removal (2019)

Willeit, M. ; Ganopolski, A. ; Calov, R. ; [weitere]

American Association for the Advancement of Science (AAAS)

In: Science Advances, 5 (4). eaav7337.

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Publikationsdatum: 2021-01-08

Beschreibung: Variations in Earth’s orbit pace the glacial-interglacial cycles of the Quaternary, but the mechanisms that transform regional and seasonal variations in solar insolation into glacial-interglacial cycles are still elusive. Here, we present transient simulations of coevolution of climate, ice sheets, and carbon cycle over the past 3 million years. We show that a gradual lowering of atmospheric CO2 and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO2 decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO2 decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO2 concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.

Materialart: Article , PeerReviewed

Format: text

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