Paleoclimate records have been used to estimate the modern equilibrium climate sensitivity. However, this requires understanding how the feedbacks governing the climate response vary with the climate itself. Here we warm and cool a state-of-the-art climate model to simulate a continuum of climates ranging from a nearly ice-covered Snowball Earth to a nearly ice-free hothouse. We find that the pre-industrial (PI) climate is near a stability optimum: warming leads to a less-stable (more-sensitive) climate, as does cooling of more than 2K. Physically interpreting the results, we find that the decrease in stability for climates colder than the PI occurs mainly due to the albedo and lapse-rate feedbacks, and the decrease in stability for warmer climates occurs mainly due to the cloud feedback. These results imply that paleoclimate records provide a stronger constraint than has been calculated in previous studies, suggesting a reduction in the uncertainty range of the climate sensitivity.
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http://dx.doi.org/10.1038/s41467-024-50406-w | DOI Listing |
Astrobiology
January 2025
Department of Earth and Planetary Sciences, Birkbeck University of London, London, United Kingdom.
Eccentric planets may spend a significant portion of their orbits at large distances from their host stars, where low temperatures can cause atmospheric CO to condense out onto the surface, similar to the polar ice caps on Mars. The radiative effects on the climates of these planets throughout their orbits would depend on the wavelength-dependent albedo of surface CO ice that may accumulate at or near apoastron and vary according to the spectral energy distribution of the host star. To explore these possible effects, we incorporated a CO ice-albedo parameterization into a one-dimensional energy balance climate model.
View Article and Find Full Text PDFJ Immigr Minor Health
December 2024
School of Interdisciplinary Science, Faculty of Science, McMaster University, Hamilton, ON, Canada.
A growing body of evidence suggests that leisure-time physical activity (LTPA) impacts one's mental health (MH) positively. The suggested MH benefits of LTPA may present a promising avenue to promote the MH of immigrants/refugees, who often face various stressors that may impede their MH. The CAN-HEAL study aimed to examine LTPA needs as they pertain to MH among Arab Canadians.
View Article and Find Full Text PDFNatl Sci Rev
November 2024
International Center for Isotope Effects Research, Nanjing University, China.
A synthesis of global barite sulfate isotope data from approximately 635 million years ago, at the end of a global glaciation, undermines the hypothesis that river sulfate was the primary carrier of the distinctive 17O-depleted atmospheric O2 signature of the time. Instead, an aqueous H2S oxidation model on the shelf emerges as a compelling alternative, though it demands extensive validation across multiple fronts by the scientific community.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
November 2024
Department of Earth and Planetary Science, University of California-Berkeley, Berkeley, CA 94720.
The Snowball Earth hypothesis predicts global ice cover; however, previous descriptions of Cryogenian (720-635 Ma) glacial deposits are limited to continental margins and shallow marine basins. The Tavakaiv (Tava) sandstone injectites and ridges in Colorado, USA, preserve a rare terrestrial record of Cryogenian low-latitude glaciation. Injectites, ridges, and chemically weathered crystalline rock display features characteristic of fluidization and pervasive deformation in a subglacial environment due to glacial loading, fluid overpressure, and repeated sand injection during meltwater events.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
November 2024
Department of Geosciences, Virginia Tech, Blacksburg, VA 24061.
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