Oceanic crustal carbon cycle drives 26-million-year atmospheric carbon dioxide periodicities


"Atmospheric carbon dioxide (CO2) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, and orogenic events and have previously been linked to an extraterrestrial mechanism. [...]

Source: Science Advances
Authors: R. Dietmar Müller and Adriana Dutkiewicz
DOI: 10.1126/sciadv.aaq0500

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As CO2 Goes Up, Ocean Health Goes Down

"June 8th is World Oceans Day, a day to raise awareness of the ocean’s importance to the planet. 93 percent of the excess heat absorbed by the climate system goes into our oceans, creating major consequences. While more extreme storms and rising sea levels are some of the impacts of warmer oceans, rising CO2 levels and the resulting warmer oceans are impacting ocean health itself. The most well­known effects are coral bleaching and ocean acidification, but an emerging issue is the decreasing oxygen levels in the warming waters. [...]"

Source: Climate Central

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Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane


"Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 106 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO2) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea−air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO2 uptake rates (−33,300 ± 7,900 μmol m−2⋅d−1) twice that of surrounding waters and ∼1,900 times greater than the diffusive sea−air methane efflux (17.3 ± 4.8 μmol m−2⋅d−1).  [...]"

Source: Proceedings of the Nathional Academy of Sciences of the United States of America (PNAS)
Authors: John W. Pohlman et al.
DOI: 10.1073/pnas.1618926114

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