Why are there two snowball earth events?

"Snowball Earth" means that the earth's surface is covered with ice from the equator to the poles and becomes a big snowball. The two "snowball earth" events mentioned by the subject should refer to the Neoproterozoic global snow-covered events from 800 million to 550 million years ago, and this time it is what geologists generally call "snowball earth" events. The second time should refer to the two ice ages of Pleistocene (2.6 million years ago-1 10,000 years ago).

The first snowball earth event

"Snowball Earth" event is closely related to the great changes of the whole earth system in the late Precambrian (late Neoproterozoic), and it is by no means an isolated glacier event. Unlike the whole Phanerozoic glacier, the Neoproterozoic glacier advanced to the equator and its adjacent sea surface. Although there are different hypotheses and explanations for this rare glacier phenomenon, more and more researchers associate it with "snowball earth" and consider it together with the rupture of Rodinia supercontinent, the activity of super mantle plume and the paleomagnetic true pole drift.

Similarly, before and after the Neoproterozoic Snowball Earth, the oxygen content in the atmosphere also experienced a significant increase. The deep sulfide ocean, which lasted for nearly 654.38 billion years, was transformed into an oxidized ocean, and the carbon, sulfur and strontium isotope records of seawater changed the most in geological history. Shortly after "Snowball Earth", multicellular metazoa appeared on the earth, and then entered the Cambrian "Big Bang". This series of major geological events shows that they are closely related. From this point of view, the Neoproterozoic "snowball earth" was caused by the transformation of the earth system at that time.

The second snowball earth event

There were two ice ages in all. The first time was the Pleistocene, 6.5438+0 million years ago. At that time, human beings had just begun to evolve. Because the earth's orbit around the sun has changed, the continental margin along the North Atlantic coast is covered with thick ice.

The second time was about 2 1000 years ago. Most parts of North America and Europe were covered by ice with a thickness of 2 kilometers, which caused the sea level to drop by as much as 120 meters. This ice age affected at least 30% of the earth's surface and led to the extinction of some creatures.

Before answering this question, explain what is a "snowball earth":

Snowball Earth is a term in geological history. It means that the surface of the earth is completely frozen from the poles to the equator, and the earth is covered with snow and ice, turning into a big snowball.

There are two famous snowball earths in the history of the earth:

The first time was 2.4 billion to 2,654.38 billion years ago, which lasted for 300 million years and was called the Huron Ice Age. The cause of the first snowball earth was that bacteria (cyanobacteria) began to absorb carbon dioxide in the atmosphere through photosynthesis, which led to the reduction of greenhouse gases. At that time, the heat of the sun shining on the earth was only 85% of today's, so the temperature of the earth dropped to MINUS 50 degrees Celsius. From the poles to the equator, the land and sea are completely frozen and become a snowball earth.

Legend: the process of the earth becoming a snowball, the picture comes from the internet.

Legend: Frozen earth surface, the picture comes from the Internet.

The second time was 750 million years ago, when the mainland became small pieces and gathered around the equator, which changed the ocean currents and led to a slow decline in global temperature. Eventually, the surface temperature dropped to MINUS 50 degrees Celsius, and glaciers were everywhere from the poles to the equator. The thickness of sea ice reached 1000m, and the whole earth was almost covered with white ice and snow (except a few areas on the equator). Seen from space, the earth is white, just like a snowball. This snowball incident lasted for 20 million years, from 720 million years ago to 700 million years ago.

The extreme cold has dealt a serious blow to life, and they have to hide in the depths of the ocean and live hard. After the extreme cold, the earth finally began to save itself, and the volcanic eruption released a lot of carbon dioxide to raise the temperature. Warmth provides an opportunity for cyanobacteria to grow wildly. The oxygen released by countless cyanobacteria makes the oxygen content in the atmosphere soar by nearly 10 percentage point, which provides conditions for the outbreak of life. After that, life on earth is about to usher in the CAMBRIAN explosion of life!

"Snowball Earth" is a proper term of geography, and its literal meaning is not difficult to understand. This means that the earth is completely covered with ice and snow and looks like a huge snowball.

There have been two snowball earth events in the history of the earth. The first time was about 800 million to 550 million years ago, when the whole surface of the earth was completely covered with ice and snow. The second time was when life just appeared on the earth. These two periods can be collectively called "Ice Age". So when it comes to "ice age", is it easy to think of "ice age"? In fact, there is a certain difference between the two. Simply put, the "ice age" can be as long as most of the earth is covered with ice and snow. In the history of the earth, there have been at least 1 1 ice ages, including four Great Ice Ages. The Precambrian and Paleozoic ice ages lasted for tens of millions of years, while the Cenozoic ice ages lasted for two million years. The most violent of these four "Great Ice Ages" was the ice age from 800 million years ago to 550 million years ago. The end of this ice age may have indirectly promoted the later Cambrian life explosion, but this theory is controversial.

The emergence of the Great Ice Age had a period of1.500 million years. There are different opinions about the causes of the Great Ice Age, but researchers think it may be related to the periodic operation of the solar system in the Milky Way. The last ice age was about 18000 years ago. According to the research results of scientists, the climate at that time was extremely cold, and about one third of the world's land was covered with 240 meters thick ice. There have been two ice ages in world history. Before the first ice age, there were almost no evolved animals, only undeveloped animals, and there was ice and snow everywhere. After the first ice age, great progress was made and animals became huge. At the same time, after many generations, large animals disappeared and were replaced by smaller animals, namely Paleocene, Eocene and Oligocene.

800 million years ago, the continents of the earth did not split, but were connected into a big plate near the equator. Later, because of volcanic activity, the mainland split and formed several small continents, which led to a large increase in the coastline of the land and brought many consequences. First, the increase in biological activities at the seaside has led to the absorption of a large amount of carbon dioxide. Second, the weathering of continental silicate increased, absorbing a lot of carbon dioxide. These two results lead to the rapid reduction of carbon dioxide in the atmosphere. Of course, this is only a hypothesis, and if this hypothesis holds, then after calculation, the ice sheet at that time was one kilometer thick, and when it was pushed near the equator, the temperature of the earth dropped to about MINUS 50 degrees Celsius. But at the same time, the volcanic activity of the earth continues. Volcanic activity leads to the release of a lot of carbon dioxide. When the content of carbon dioxide reaches a certain level, it forms a "greenhouse effect", thus melting the "snowball earth".

So why did the snowball earth form? This question is inconclusive, even if the earth is completely covered. It can only be said that snowball earth is a very extreme glaciation. Of course, there are actually different voices here. Scientists believe that snowball earth may not be as bad as imagined. In other words, the earth was not a frozen snowball 800 million to 550 million years ago. At that time, it was probably that the climate on the earth was mild and the soil was muddy, which did not last for hundreds of millions of years.

During the "Snowball Earth" period, some species survived and evolved into new species. "Snowball Earth" has a shelter in the open water, or at least a crack in the ice, which makes the life of the earth continue in the ice. Now, when we talk about climate issues, the first thing that comes to mind is "greenhouse effect" and "global warming". But have you ever thought that the earth will become a big snowball one day, and it is no longer suitable for survival at that time? Scientists say that it is not impossible for the earth to experience the "snow earth" again. If the environment is greatly damaged, the snowball earth may reappear. So, is global warming necessarily a bad thing (perhaps for an island country and some coastal cities)? Finally, the reason why "Snow Earth" has attracted the attention and research of so many scientists is because there is evidence that after the "Snow Earth" incident, the oxygen content on the earth has greatly increased, and the evolution of life on the earth has achieved a great leap.

Friends who have seen the sci-fi movie The Day After Tomorrow must remember the frozen world vividly, but in fact, the surface of the earth is covered with ice and snow for many periods. Geologists call these periods the ice ages of the earth. The earth is colder at this time. When this situation is particularly serious, most of the earth's surface is covered with thick ice and snow, which is called the Great Ice Age. The earth at this time is often called snowball earth, frozen soil, etc., because

At present, the area of glaciers on the earth is about 6.5438+0.5 million square kilometers, mainly concentrated at the poles of the earth and some plateaus. However, when the Great Ice Age comes, the area of glaciers will occupy the ocean and land in temperate regions of the earth, and sometimes even glaciers will exist in tropical regions. According to geological and archaeological findings, this Great Ice Age happened three times. The first time happened at the end of Proterozoic about 600 million years ago, which was called the Sinian Great Ice Age. The time of the Great Ice Age was slightly different on all continents in the world, and the time span was very large, from 800 million years ago to 550 million years ago. At that time, the animals and plants on the earth mainly existed in the ocean, and the land was still barren, so the impact on the vivid plants on the land was still relatively small.

The second time occurred from Carboniferous to Permian about 300 million years ago. After the Great Southern Ice Age, the earth experienced a warm period of 330 million years, and the life species on the earth flourished for a long time. In the late Paleozoic, the earth entered the second Great Glaciation, namely the Carboniferous-Permian Great Glaciation, which occurred 350-270 million years ago, from the Middle Carboniferous to the Early Permian. Because the Carboniferous and Permian belong to the Late Paleozoic, it is also called the Late Paleozoic Great Ice Age. The Great Ice Age mainly occurred in Gondwana, in which South America and Africa occurred and subsided earlier, and India and Australia later.

The third Great Ice Age is the most famous Quaternary Great Ice Age, and it also has the greatest influence on the current ice age. Its moraine layer is the most complete, widely distributed and studied in detail. According to the change of glacier coverage, this glacial period can be divided into several glacial periods and interglacial periods. The degree of glacier development in each continental ice age varies greatly. For example, the ice sheet in Europe once reached 48 north latitude, while the ice sheet in Asia only reached 60 north latitude.

Although it seems that the Quaternary Great Ice Age is shorter than the previous two times, geologists generally believe that the earth is still in the interglacial period, because the present climate is colder than many periods in history, and it is judged that the Quaternary Great Ice Age is not over yet.

From the time interval of the above three ice ages, it can also be found that this period occurs every 300 million years, but the specific reasons are still unclear. Some people think that this is related to the operation of the solar system in the Milky Way, but its time does not coincide with the cycle of the sun in the Milky Way. Some people think that this is related to lava activities in the earth, changes in the earth's orbit, changes in the earth's atmosphere and even activities in the ozone layer, but there is no conclusive evidence to prove it.

First, let's explain what snowball earth is.

In fact, "Snowball Earth" is already a very vivid description. Seen from space, the earth looks like a snowball, which means that from the equator to the polar regions, the earth is almost covered by glaciers or snow. It also means that the temperature on the earth is extremely low during this period, MINUS forty or fifty degrees!

At that time, the temperature at the equator was almost equivalent to the temperature at the South Pole now, which made people shudder ~

Since the earth was born 4.6 billion years ago, it has experienced four ice ages, and the earth has always existed alternately in cold and hot.

The last snowball earth relatively close to us was 800 million to 550 million years ago, probably during the Studt Ice Age and the marino Ice Age.

Another time, Snowball Earth was farther away, about 2.45 billion to 2.22 billion years ago. This time should be the time when life just appeared on the earth. There are several hypotheses about why snowball earth appears.

For example, about the "snowball earth" 2.4 billion years ago, scientists speculated that it might be because blue-green algae released oxygen into the atmosphere, which led to methane oxidation. Methane is a greenhouse gas. Without methane, the atmosphere cannot keep the earth warm. The temperature dropped to -50, and even the equator was covered with ice more than 1 km thick.

Another example is "Snowball Earth" 800 million years ago. Some scientists believe that volcanic activity leads to the division of continental plates, the increase of coastline, the movement of more organisms on the shore and photosynthesis, and the weathering of continental silicates. Both of these changes will lead to the reduction of carbon dioxide. ...

Carbon dioxide is also a kind of greenhouse gas, and its rapid reduction finally turned the earth into a cold palace.

However, the earth is actually very tenacious, and so is life on earth.

In the past four billion years, our earth has experienced more severe cold and heat than it is now, but it can always maintain the balance between its environment and biology through a set of adjustment and feedback measures.

In fact, the "Snowball Earth" incident is not only bad. Although many creatures died out because of the extreme cold of the earth, when the earth began to warm up, a large number of nutrients in the ocean were also gestating new life and more complex ecosystems.

Moreover, the alternation of hot and cold on the earth has never stopped, and it is very likely that a snowball earth may appear in the distant future.

As the title suggests, the earth has been covered with snow for hundreds of millions of years, completely frozen from the poles to the equator, becoming a big snowball.

Through the analysis of scientists and meteorological researchers, under such extreme conditions, all the animals and plants on the earth are almost extinct, no one lives, but thanks to the hot springs in the deep sea, the earth can survive and be resurrected.

So what is the reason for this phenomenon? The researchers found that this is not a coincidence. Before the earth was covered with ice and snow, there was a large-scale volcanic eruption on the earth, which would have a serious impact on the atmosphere. Long-term volcanic eruption will produce an aerosol, which will have a strong cooling effect and lead to climate change. This situation is the fuse that causes the earth to freeze. Of course, whether there was ice or how long it lasted, or why it happened.

Factors and mysteries remain an unsolved problem. Whether there will be such extinction in the future is still a question worth studying!

What's it like to live in such a warm environment? I'm afraid no one wants to try, and I'm afraid it's impossible to have inventory in case of extinction!

Two snowballs must have been said many times less.

Because the earth has four seasons. For about 60 thousand years, it has been covered with ice and snow every three days. Then the weather gets warmer. Melting from the equator is like only the poles are covered with ice. And then melt it all. Then gradually all covered with snow and ice. Endless cycle.

If fire can destroy everything, then cold can save everything. . . .

The snowball of the earth sounds amazing. Did the earth become a snowball? Yes, the snowball refers to an extremely cold weather event on the earth. The temperature is very low. From the polar regions to the temperate regions and even to the tropics, the earth is covered with ice.

During the 4.6 billion years of the earth's reproduction, there were three major ice ages, namely Precambrian Neoproterozoic Ice Age, Carboniferous-Permian Ice Age and Quaternary Ice Age. Among them, the Precambrian Neoproterozoic Great Glacier has four more glaciers, especially in Studt and marino, which belong to ocean glaciers. The global ocean is completely frozen, the thickness of the surface ice reaches the kilometer level, and the earth is wrapped into a veritable snowball.

Why did the snowball earth form? At present, there is no unanimous view on this issue in the scientific community. There is a saying that the snowball event is related to the plate structure of the earth, precisely because the earth's surface is not a complete plate, the plates move independently, resulting in volcanic movement, and volcanic eruption leads to the snowball event. The researchers analyzed that before the snowball earth event, a long-term volcanic eruption produced a large number of aerosols, which had a strong cooling effect on the earth. There is also a saying that volcanic rocks absorb a lot of carbon dioxide, and when a lot of carbon dioxide is discharged from the atmosphere, it will achieve the effect of cooling the earth.

The first time I saw this word, I only knew that human research believed that the earth experienced four ice ages, and the panda was an ancient species that survived the fourth ice age. Although some modern climate experts think that global warming is a trend, others think that the earth may usher in the fifth ice age. Humans will live underground, or go to Wolong to keep company with pandas and see how pandas escaped from the ice age!