Asteroid sedding earth causes dinosaur extinction but brings life

BEIJING, March 5 (Xinhua) — A huge asteroid hit the Earth 66 million years ago, leaving a crater more than 110 miles wide on the Yucatan Peninsula, leaving a trail of death shrouding the planet, according tomedia reports. The impact released more than 12,000 cubic miles of material into the air, leading to decades of winter and ocean acidification. As a result of this tragic event, three-quarters of the world’s species, including dinosaurs, disappeared.

However, the disaster is not entirely a bad thing, and an international study involving 36 scientists suggests that the mass extinction of species at the end of the Cretaceous period could reduce the impact of large-scale volcanic eruptions that coincide with the collision of the planet with asteroids. Asteroid collisions on Earth prompted the oceans to absorb large amounts of greenhouse gases released by the volcanic plateaus of ancient India (Degan Plateau) and inhibit global warming, otherwise the survival of early mammals and many other species would have many troubles and adverse effects.

Research suggests that an epic volcanic eruption lasted 400,000 years when an asteroid hit Earth, and some scientists believe that volcanic gas may have been partly responsible for the mass extinction of species. But according to a recent assessment of global temperatures published in the journal Science, large-scale volcanic eruptions seem unlikely to lead to the extinction of the dinosaurs.

Asteroid sedding earth causes dinosaur extinction but brings life

The asteroid appears to have acted alone, and its huge impact on marine plankton may have eased the subsequent global warming, as volcanic eruptions continued for another 300,000 years.

Asteroid sedding earth causes dinosaur extinction but brings life

Floating Palm Tree

Study co-author Pincelli Hull, an ancient oceanographer at Yale University in the United States, said that sampling in muddy sediments on the ocean floor led to the rapid extinction of plankton with calcium shells when asteroids collided with Earth and dropped large amounts of tiny glass beads from the sky.

“These plankton have been hit hard by an asteroid collision, and we think that this collision, which releases a lot of sulfur and nitrous oxide, may cause ocean acidification to dissolve the plankton shell, which is like throwing a piece of calcium plankton residue into vinegar, but the ocean is not that acidic,” Hull said. So the plankton shell dissolves much slower and does not produce bubbles.

The same sediments reveal how global temperatures change over time, and Hull explains that the change should reflect any significant impact of the gas released by the Degan volcano, including carbon dioxide.

“The viscosity of the mud samples we found in the deep sea is comparable to toothpaste, it’s not made of rocks, unlike the mud we’re familiar with on land, but by microscopic fossils of lime plankton that will land on the ocean floor after death,” Hull said. By identifying only plankton at different levels of marine sediments, a comparative analysis of the ocean climate at the time, some species equivalent to the discovery of palm trees in the Arctic ocean. But the shell chemistry of these floating palm trees contains more information. “

Changes in ocean temperatures affect carbon-oxygen isotopes in plankton, and by combining deep-sea mud data collected from around the world, researchers can reconstruct how global temperatures have changed over hundreds of thousands of years.

Before the climate upheaval

Using equations, the researchers designed a new computer model that captures the relationship between temperature changes and the carbon cycle at different times of the Earth, including now.

In February 2019, two studies published in the journal Science rekindled the 40-year-old scientific controversy, with the most reliable hypothesis being that the greenhouse gases of the Degan Plateau were either released 200,000 to 300,000 years before the extinction of the species at the end of the Cretaceous period, or before and after the mass extinction of the late Cretaceous species. Courtney Sprain, a geologist at the University of Florida, first suggested in her research paper that the latter hypothesis is more scientific.

“I’m certainly excited to see that the previous hypothesis is consistent with our latest research, and both studies in 2019 take into account the massive gas eruptions that follow the asteroid collision on Earth,” Spree said. “

But the main difference between the two studies was by geologist Blair Schoene, who suggested that volcanic activity occurred at frequency 100,000 years before the mass extinction event, which could destroy the environment and, along with asteroids, cause global destruction of Earth’s species.

But the latest computer simulations do not support this hypothesis, showing that global temperatures began to cool before the asteroid hit Earth.

Scientists still question how much gas was released before and after the extinction, and about 200,000 years before the extinction, they looked at a warm period closest to an asteroid collision, and found that the Earth’s warming peaked at 2 degrees Celsius, and another less obvious warming occurred 200,000 years after the asteroid collided with Earth.

Donald Penman, a geochemist at Yale University and co-founder of the climate model, said a weakening trend in warming does not necessarily mean less gas is released by the Degan Plateau volcano, and there may be a more interesting explanation.

“After the extinction of most calcium plankton, the model showed that the compounds they would have accumulated in their shells allowed the oceans to absorb more volcanic carbon dioxide gas and reduce the effects of global warming trends,” Penman said. “

Heather Birch, an paleontologist at the University of Bristol in the UK, believes that after an asteroid collides with Earth, the composition of plankton varies, which may affect carbon absorption. Only a small fraction of plankton become fossils, so we need more research to analyze how large amounts of carbon dioxide are absorbed.

But given the current acidification of the oceans again, this time due to increased carbon dioxide caused by humans, could another massive calcification of plankton extinction save us from the worst of climate change?

Hull said temperatures rose thousands of years after the extinction of plankton at the end of the Cretaceous period, and the oceans began to absorb more carbon dioxide, but on the time scale associated with human society, it meant that humans would face thousands of years of climate upheaval in the future. (Ye Ding Cheng)