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Dissolved oxygen levels in the Proterozoic surface ocean decreased from the Equator towards the mid–high latitudes, the opposite of the modern latitudinal gradient, according to a compilation of I/Ca proxy records and Earth system modelling.

Carbon release rates during the Palaeocene–Eocene Thermal Maximum are difficult to constrain. Comparing relative rates of carbon cycle and climate change at the event’s onset suggests emissions were much slower than anthropogenic emissions.

A brief period of warming 55.9 Myr ago has been attributed to the release of massive amounts of carbon. Geochemical and model data suggest the peak rate of carbon emission during this interval was relatively slow, and significantly lower than present-day levels of carbon emissions to the atmosphere.

The carbon cycle plays a central role in climate change. An analytical framework shows that the influence of atmospheric carbon dioxide concentrations on climate is more sensitive to carbon perturbations now than it has been over much of the preceding 400 million years.

Flood basalt eruptions have been linked to extinction events. Numerical simulations suggest that the environmental effects of sulphur emissions from these volcanoes would be limited unless the eruptions were frequent and sustained.

Analysis of a series of Earth system model experiments shows that continental rearrangement during the Phanerozoic had a marked influence on variations in ocean oxygenation, independent of atmospheric pO₂.

A short-lived carbon release preceded the PETM. Here the global nature of this is confirmed, effects on the surface ocean carbon cycle are resolved, and a thermogenic CO₂ source is inferred.

Increasing concentrations of carbon dioxide in sea water are driving a progressive acidification of the ocean, with as yet unclear impacts on marine calcifying organisms. Simulations with an Earth system model suggest that future changes in the marine environment could be more severe than those experienced during the Palaeocene–Eocene thermal maximum, both in the deep ocean and near the surface.

The early Eocene was marked by a series of abrupt warming events. Numerical modelling suggests that the events were the result of nonlinear interactions between orbital forcing, ocean circulation and the carbon cycle.

Transient global warming is nearly proportional to cumulative carbon emissions. A theoretically derived equation shows that this relationship stems from the partially opposing climate effects of oceanic uptake of heat and carbon.

Elevated atmospheric CO₂ during the Palaeocene–Eocene Thermal Maximum coincided with substantial declines in the pH and carbonate saturation state of the ocean.

Combining geological evidence and modelling, Crichton and others find life in the ocean Twilight Zone (200 m to 1000 m depth) is vulnerable to warming due to lower food supply. High emissions may lead to severe depletion and extinction in this habitat

Reorganized ocean circulation during Late Ordovician cooling altered oxygenation through the water column, provoking a new look at the extinction mechanism, according to anoxia reconstructions using the I/Ca proxy and Earth system modelling.

The diversity hotspots hypothesis attributes the overall increase in global diversity during the Late Mesozoic and Cenozoic eras to the development of diversity hotspots under prolonged conditions of Earth system stability and maximum continental fragmentation.

The Paleocene–Eocene boundary coincided with runaway global warming possibly analogous to future climate change, but the sources of greenhouse gasses have remained unresolved. Here, the authors reveal volcanism triggered initial warming, and subsequent carbon was released after crossing a tipping point.

Warming-enhanced microbial respiration can explain marine anoxia patterns across depth, a key driver of the end-Permian mass extinction, according to biogeochemical modelling and geochemical proxy records.

Boron and carbon isotope data, used in an Earth system model, show that the Palaeocene–Eocene Thermal Maximum was associated with a much greater release of carbon than thought, most probably triggered by volcanism in the North Atlantic.

A detailed reconstruction of the calcium carbonate compensation depth—at which calcium carbonate is dissolved—in the equatorial Pacific Ocean over the past 53 million years shows that it tracks ocean cooling, increasing as the ocean cools.

Single-foraminifera measurements of the PETM carbon isotope excursion from Maud Rise have been interpreted as indicating geologically instantaneous carbon release. Here, the authors explain these records using an Earth system model and a sediment-mixing model and extract the likely PETM onset duration.

After the Cretaceous/Palaeogene mass extinction event, nannoplankton communities exhibited volatility for 1.8 million years before a more stable community emerged, coinciding with restoration of the carbon cycle and a fully functioning biological pump between the surface and deep sea.

The chemical breakdown of rocks can be enhanced by spreading silicate granules over land. Research suggests that this measure, which increases the rate at which CO₂ is locked up in ocean carbonates, could lower atmospheric CO₂ by 30–300 ppm by 2100.

A reconstruction of atmospheric CO₂ concentration from boron isotopes recorded in planktonic foraminifera examines climate–carbon interactions over the past tens of millions of years and confirms a strong linkage between climate and atmospheric CO₂.

The Palaeocene–Eocene Thermal Maximum was associated with a massive release of carbon. Marine sediments suggest a temporary deepening of the calcite compensation depth, indicating extensive silicate weatheringin the aftermath of the event.