same thing now
A massive rise in oceanic carbon dioxide followed by a sharp drop in trace metals crucial for marine life set the stage for a mass extinction about 183 million years ago in the early Jurassic. This sequence coincided with the loss of nearly 90 percent of ocean species and roughly 75 percent of land species as carbon levels spiked beyond previous estimates.
Researchers publishing in AGU Developments measured a decline in molybdenum within the ocean. Molybdenum is a biologically important micronutrient that dissolves in seawater. The evidence indicates that prior to an extinction event this metal fell to residual levels because the system lacked oxygen, preventing the usual reduction and oxidation reactions that drive nutrient cycles, a state known as euxinia.
Yet the study did not stop with the data on molybdenum. It also suggested that the carbon cycling between the sea and the atmosphere was much more substantial than previously thought. One of the paper’s authors, Jeremy Owens, explained that the amounts of carbon involved likely climbed to a similar scale as the modern increase driven by human activities.
Re-creation of the penultimate mass extinction by researchers is illustrated in images from the study, highlighting the dramatic shifts in ocean chemistry and the ecological collapse that followed.
There is an inverse relationship between carbon and molybdenum. When molybdenum decreased to depths corresponding to 41 gigatons, the ocean stored about 244,000 gigatons of carbon dioxide. The researchers analyzed rock records from three sites in Canada’s Alberta region, which were once part of the vast ocean surrounding the ancient supercontinent Pangea. Because these locations were connected to the global ocean in the past, they offer a snapshot of what happened in the world’s oceans 183 million years ago.
Thus a decline in molybdenum signaled a large rise in oceanic organic carbon concentrations, reaching levels that challenged life itself. The team estimated that the ocean’s CO2 concentration during that period was higher than earlier models predicted and suggested that previous carbon estimates based on volcanic emissions needed revision to reflect real-world dynamics more accurately.
According to the study, the drop in molybdenum preceded the onset of an extinction that began about one million years later and extended over roughly two million years in total, far longer than prior estimates. Life eventually recovered, but the rebound took hundreds of thousands of years, underscoring the long-lasting consequences of extreme ocean chemistry shifts.
Volcanism is noted as a key driver in the narrative, helping to shape the environmental context that amplified these changes in carbon and trace metals. The research emphasizes that current climate change shares striking parallels with the ancient pattern: rising atmospheric CO2 and a warming world are altering ocean chemistry in ways that threaten marine and terrestrial life alike.
Today the climate trajectory mirrors the past in important respects. Elevated CO2 levels accumulate in the atmosphere and the oceans, and the disruption of micronutrient cycles such as molybdenum could recur. Scientists caution that the risk of a sixth mass extinction remains a serious consideration if these trends continue unchecked, particularly under human influence on the environment.
The study ultimately reinforces the view that history offers a warning about the fragility of life during drastic oceanographic changes. It also underscores the need for a realistic assessment of carbon fluxes and their impact on marine ecosystems in the face of ongoing anthropogenic pressures.
Further readings and analyses are available through the AGU Developments journal, as summarized by study authors who emphasize the broader implications for modern climate science and policy. This research contributes to a growing body of evidence that links ocean chemistry, atmospheric carbon, and global biodiversity across deep time, offering a framework for understanding today’s environmental challenges.
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