The analysis of the chemical composition of fossilized shells led scientists to astonishing conclusions.
Despite the trend of global warming in recent decades, the modern climate is overall significantly colder than during the age of dinosaurs. Scientists are debating the reasons for this, but gradually more new elements are being added to the puzzle.
As DailyGalaxy reports, a recently published study puts forward a well-founded hypothesis that the sharp decline in calcium levels in the ocean may have been an important factor influencing the transition of Earth from a global greenhouse during the age of dinosaurs to the cold world with polar snow caps today.
An international group of researchers traced geological data to see how calcium levels in the ocean have changed since the extinction of the dinosaurs and noted that its concentration has decreased by more than half during the Cenozoic era.
According to lead author Dr. David Evans, during the age of dinosaurs, the calcium-rich ocean was less effective at retaining carbon, which is a key element of greenhouse gases such as carbon dioxide and methane.
Thus, as the calcium content in seawater fell, the oceans absorbed more carbon, and the concentration of carbon dioxide in the atmosphere decreased. This led to the process of global cooling.
Why Oceans Started Accumulating Carbon
As Professor Yair Rosenthal explained, the decline in calcium concentration is likely due to the slowdown of seafloor spreading – a tectonic process that forms new oceanic crust. Simply put, significantly less calcium from the deep layers of the Earth's crust began to enter the seawater.
However, this process alone could not have triggered the accumulation of carbon in the water. Here, marine organisms came into play. The decrease in calcium concentration in the water forced them to seek alternative "building materials" for their shells and skeletons.
Analysis of the chemical composition of fossilized shells of single-celled marine organisms indicates that these organisms began to actively use carbon as a building material. As a result, carbon dioxide entering the ocean from the atmosphere was utilized by marine inhabitants for their needs and no longer returned to the atmosphere.
Ultimately, these physiological features of tiny marine organisms over 66 million years led to enormous changes in planetary climate.
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