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Snowball Earth climate dynamics and Cryogenian geologyâgeobiology
Geological evidence indicates that grounded ice sheets reached sea level at all latitudes during the longâlived Sturtian (717â659 Ma) and Marinoan (ca 645â635 Ma) glaciations. Combined U-ÂâPb and Re-ÂâOs geochronology suggests that the Sturtian glacial onset and both terminations were globally synchronous. Geochemical data imply that atmospheric pCO2 was 102x modern at the Marinoan termination, consistent with Snowball Earth hysteresis. Sturtian glaciation followed the breakup of a tropical supercontinent, and its onset coincided with the equatorial emplacement of a large igneous province. Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual-mean Hadley circulation, resulting in equatorial net sublimation and net deposition elsewhere. Oceanic ice thickens, forming a sea glacier that flows gravitationally toward the equator, sustained by the hydrologic cycle and by basal freeze-on and melting. Tropical ice sheets flow faster as CO2 rises, but lose mass and become sensitive to orbital forcing. Dust accumulation in the equatorial zone engenders supraglacial oligotrophic meltwater ecosystems, favorable for cyanobacteria and many eukaryotes. Meltwater flushing through moulins enables organic burial and submarine deposition of subaerially-Ââerupted volcanic ash. The subglacial ocean is turbulent and wellÂâmixed, in response to geothermal heating and conductive heat loss through the ice cover, increasing with latitude. Cap carbonates, unique to Snowball Earth terminations, are products of intense weathering and ocean stratification. Whole-Âocean warming and ice-sheet forebulge collapse allow marine coastal inundations to progress long after ice-sheet disappearance. The evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms
Release from incarceration, relapse to opioid use and the potential for buprenorphine maintenance treatment: a qualitative study of the perceptions of former inmates with opioid use disorder
Incidence and Prevalence of Incarceration in a Longitudinal Cohort of Women at Risk for Human Immunodeficiency Virus in the United States, 2007â2017
The academic and health policy conference on correctional health: evaluation of its academic and scientific impact
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