BEIJING, Dec. 30 ( Xinhua) — With rising greenhouse gas emissions and the earth’s warming, the global climate is getting closer to the Earth’s climate in ancient times, according tomedia reports. This has raised concerns among scientists about the history of the Earth’s climate, especially during warmer periods such as the Last New World. Scientists believe that we are now moving towards the climate of the Upper Neoternist period.
The artist depicts the “snowball earth”.
At the same time, scientists have studied other geological ages further. Although the Earth at these times is very different from the present, it can also help us better understand the Earth, and even the human race itself.
Ice age is an example of this. It was about 720 million to 635 million years ago, when the Earth was experiencing the most extreme ice age in its history, and the entire planet was frozen, hence the name “snowball Earth.”
Today, only parts of Antarctica and Greenland are covered with ice sheets all year round. But during the ice age, most of the surface was covered with ice and snow.
But somehow, the ice age is also the first time in the fossil record that complex animal signs appear. These creatures laid the foundation for the “golden age” of the animal world, and this glory continues to this day. In a new study, researchers analyzed the chemical composition of rocks during the ice age in the hope of learning more about the strange world, such as why animals not only survived, but even reached new heights.
During the ice age, almost the entire surface of the earth was covered with ice and snow, and the huge ice sheet stretched all the way to the tropics. (However, there was some debate about the extent of the freeze at the time.) Most of the land is combined to form the Rodenha supercontinent. But because of the glaciers that spread around the world, almost the entire surface is frozen into a solid piece of ice. The average surface temperature is only a few degrees above zero, and some studies suggest that temperatures should be much lower at the time, possibly as low as minus 50 degrees Celsius.
There were two large-scale ice ageperiods during the ice age, called Sturtian and Marinoan. There was a brief, warmer period between the two ice ages, with melting ice and volcanic eruptions at one point. It’s a crazy time for Earth, switching back and forth between the extremes of ice and fire. But it is also a very important period, because it announces the emergence of complex animals, including our ancestors.
The question is, how on earth do these animals survive on snowball earth? The question has puzzled many people. During this period, not only were the animals on the ice difficult to survive, but so did marine life, as the frozen sea surface severely affected the ability of seawater to absorb oxygen. This seemingly contradictory problem has puzzled scientists for a long time. But a new study published in the Proceedings of the National Academy of Sciences has finally opened the door for us.
Long before the ice age, life had appeared on Earth, but it was mainly single-celled microbes. Even when multicellular organisms emerge later, they are very simple basic organisms that filter nutrients from seawater or feed on microorganisms. These early creatures have not yet developed eyes, legs, jaws, or claws, because they do not need them in a world without predators.
The Cambrian outbreak was a turning point in the history of the Earth, during which a large number of large and complex organisms were formed.
But things soon changed after the Cambrian outbreak. In less than 20 million years, the dramatic increase of biodiversity, a strong impetus to the advent of the animal age, so known as the history of animal evolution “big bang.” Some studies, however, suggest that the so-called “big outbreak” may actually consist of a series of small-scale “explosions”. But in any case, the Cambrian eruption was a major leap in the evolutionary history of life on Earth. Most of the types of organisms we know today appeared during this period, including the ancestors of humans and all other vertebrates.
But fossil records show that complex animals had emerged before the Cambrian outbreak began. These may not be the new complex creatures that emerged later, but it is clear that complex organisms already existed on Earth before the Cambrian outbreak. And these creatures appear to have emerged in the early ice age, so they had to survive the Earth’s “snowball” period. The pioneers of these complex organisms included eukaryotes (known collectively as organisms with advanced cellular structures) and, perhaps, primitive animals such as sponges.
Pictured is the Antarctic Venable ice shelf, which reaches out to the sea.
Oxygen-rich water was essential for many of the early complex organisms, especially animals. But because the ocean was under ice and oxygen was limited, scientists thought it didn’t exist. But we know that these early organisms did manage to survive on the “snowball earth” (or else there will be no offspring of us), so some scientists have come up with other hypotheses to try to explain how eukaryotes survived during the Ice Age. For example, eukaryotes may live in melting ponds above the ice sheet, rather than in the water beneath the ice sheet.
But the new study suggests that some oceans may not be as unfit for ancient life as we think.
Glacier Oxygen Pump
The study authors analyzed iron ore from Australia, Namibia and California. The iron ore was formed during the Stud ice age and was buried in a range of different glacial environments, thus helping us to gain a comprehensive picture of the ocean at the time.
Studies have shown that seawater, which was far from the coast at the time, did contain very low oxygen and high iron content, making it unsuitable for animals and other organisms that rely on oxygen to survive. But near the frozen coastline, the oxygen content of the water is staggeringly high. The researchers say this is the first direct evidence of the presence of oxygen-rich marine environments during the “snowball Earth” period, and may explain how ice-age organisms survived and thrived further in subsequent Cambrian outbreaks.
By studying Snowball Earth and Muddy Earth, scientists hope to better understand exoplanets such as Kepler-62f that may have frozen oceans.
“The evidence shows that while most of the frozen oceans are not fit for life because of a lack of oxygen, there is a large amount of oxygen-rich melt water at the land’s ice sheet, which borders the sea. Maxwell Lechte, lead author of the study and a postdoctoral researcher at McGill University in Canada, said in a press release that “this trend can be used in the case of” Glacier oxygen pump’ describes: when the glacier melts, the bubbles that were originally sealed in the ice enter the water, increasing the oxygen content of the water body. “
Glaciers are made of snow that accumulates and compresses, so the bubbles in the snow are sealed in the ice. Over time, these bubbles move down the ice and eventually escape with the melting water at the bottom of the glacier. In some areas, these bubbles may provide enough oxygen to survive the early marine animals on a “snowball planet.”
In fact, the significance of Snowball Earth to these early creatures may not be just a difficult one. There are indications that specific conditions during the ice age may have laid the foundation for the Cambrian outbreak. “Just before complex animals began to evolve, the Earth went through a period of global ice, suggesting that there may be some connection between ‘snowball Earth’ and animal evolution. “The harsh conditions of the ice age may have stimulated the organisms to differentiate into more complex forms, ” says Mr Lecht. “
Another recent study also concluded that the rise of animals was linked to a global algae bloom during the ice age. The algae outbreak was triggered by melting ice after the Sturt ice age. During the warmer period between The Sturt and The Marinino Ice Age, large amounts of melting water poured into the ocean, replenishing some of the key ingredients for the water.
Jochen Brocks, lead author of the study and a professor at the Australian National University, explained: “The Earth was frozen for more than 50 million years and huge glaciers had turned entire mountains into powder. As global temperatures rise and ice melts, the nutrients they contain are washed into the sea. “
As the high temperature recedes and the earth enters the snowball state again, the nutrient-rich cooling seawater provides an ideal environment for the global marine algae outbreak. Previously the bacteria-dominated oceans became the world of larger, more complex organisms, which in turn provided the “fuel” for survival and evolution of larger and more complex species. If the earth hadn’t become a snowball, we might never have had a chance.
“These large, nutrient-rich microbes provide sufficient energy for the evolution of complex biological systems,” Brocks notes. (Leaves)