Scientific interpretation, did humans appear to save the earth? Explain in detail the ice age on earth.

Hello, everyone, this is the previous speech!

Today we will talk about the glaciers that appeared on the earth billions of years ago.

We are used to glaciers because the whole human history is in the current iceberg period. Having said that, we need to distinguish several concepts for you first. You may often hear some words, such as Great Ice Age, Ice Age, Interglacial Age, Ice Age, Ice Age and so on. Many friends may not know. What's the difference between so many names?

It's not the same thing.

Let me give you a brief introduction. First of all, the words Great Ice Age, Ice Age and Ice Age have the same meaning. It refers to the period when there were large glaciers on the earth. It can also be said that as long as there are permanent glaciers on the earth, it is an ice age. For example, we now have large glaciers in the Antarctic continent and Greenland, so this period is an out-and-out ice age.

After the ice age, let's talk about the ice age and interglacial period. Ice age and interglacial period are included in a certain ice age, that is to say, in the ice age with a time span of tens of millions or hundreds of millions of years, there are several ice ages and interglacial periods alternating, with a time span of 654.38+ million.

During the ice age, the glacier area will expand, sometimes even to the equator. During the interglacial period, the area of glaciers will shrink, and only in high latitudes will there be permanent glaciers, just as we are now in the interglacial period after the last glacial period, which means that although it is summer, we often feel very hot.

But from the point of view of glaciology, we have been living in the ice age. Since the earth was born, it has experienced many ice ages. The first time was 2.9 billion years ago, when the earth was born 1 700 million years ago, and this first time lasted1100 million years.

The second time was when I was 2.2 billion years old, which was 2.4 billion years ago. At that time, there was a great oxidation event on the earth, which directly triggered glaciers. The great oxidation event, also known as the oxidation catastrophe, is also a very strange thing in the origin of life on earth. I won't talk about it here. It took 300 million years to recover from this ice age. After that, there was no ice age in 65.438+0.4 billion years, until more than 3.9 billion years.

Because according to geological research, the earth at that time, including the equatorial region, was completely covered with ice and snow and turned into a snowball. It would have been dangerous if it hadn't been for the later volcanic eruption. After this time, the earth should be 4 billion years old, and after 4 1 year old, there are more and more ice ages.

Since the Cambrian explosion of life 540 million years ago, various species have appeared on the earth, but they have entered an ice age every 200 million years, and it has happened three times in the last 500 million years. In other words, the diversity of species is likely to affect the occurrence of the ice age.

From this point of view, it seems not a good thing that there are so many animals and plants on the earth. So what is a healthy ecological environment? And what kind of state does the earth want to maintain? Did mankind undertake any special mission in this process?

Here we need to talk about what causes the earth to be hot and cold. The first is the content of greenhouse gases in the atmosphere. As we talked about the carbon cycle before, plants absorb carbon dioxide in the atmosphere through photosynthesis and fix carbon in the form of organic matter. After animals eat plants, this part of carbon is transferred to animals. Animals decompose these organic substances and then excrete carbon dioxide through breathing, thus forming a most basic biosphere carbon cycle.

The other is dead animals, which are buried underground for a long time, and this part of carbon is preserved. After volcanic eruption and geological activities, the carbon returned to the atmosphere, which is part of the deep carbon cycle. The above-mentioned 2.4 billion-year oxidation event was that there was too little carbon dioxide and too much oxygen in the atmosphere, which led to the outbreak of the second ice cold period.

There was also the ice age 360 million years ago, which was also due to the explosion of terrestrial plants. Excessive photosynthesis consumes a lot of carbon dioxide, which leads to a sharp drop in carbon dioxide content in the atmosphere and a drop in temperature, leading to glaciers in high latitudes.

As we all know, white will reflect more sunlight, so after the appearance of glaciers, the sunlight absorbed by the earth will be reduced, which will further aggravate the cooling of the earth. Eventually, the area of glaciers will become larger and larger, and the earth will enter an ice age.

Then if the earth wants to get rid of the ice age, it mainly depends on the greenhouse effect. For example, the snowy earth we just talked about, the whole earth is frozen, the terrestrial biosphere basically can't operate, and no plants consume carbon dioxide. At this time, the carbon dioxide released by volcanic eruption can be completely accumulated, which eventually leads to the greenhouse effect and the thawing of the earth.

From this, we can see that greenhouse gases are indeed the biggest reason that affected the ice age.

Milankovic period

1920, serbian scientist Milan kovic put forward a theory, which demonstrated the influence of eccentricity of earth orbit, inclination angle of axis and precession of rotation axis on earth climate and ice age. However, because the research on the ice age was still very limited at that time, and the exact time of the ice age and interglacial period was not grasped, his research theory did not receive immediate attention.

Later, geologists obtained more and more evidence and calculated the accurate ice age time. It was found that Milan Covic's calculation time was exactly the same, so Milan Covic's theory was quickly published in the scientific journal 1976.

However, people have been dead for almost 20 years at this time, which can be said to be a very regrettable thing. Then it is necessary to mention the Milan-Covic cycle, which mainly explains the laws of glacial and interglacial periods. Its time span is between tens of thousands and hundreds of thousands of years. For the ice age spanning tens of millions to hundreds of millions of years, it is beyond his discussion. The detailed principle of Milan-kovich cycle involves a lot of astronomical knowledge.

In a word, Milan-Covic cycle can not only accurately calculate the time of the past several glacial periods and interglacial periods, but also calculate the time of the next glacial period. According to the calculation, the next ice age may appear after 1500 years, but this prediction has a big premise, that is, if humans do not appear.

plate movement

Plate movement also has a great influence on the ice age, because it will significantly affect the global ocean currents and air currents. If all the oceans are connected without obstacles, ocean currents can smoothly send warm water from the equator to the polar regions, so that the polar regions are unlikely to freeze.

If the distribution of the mainland just blocks the ocean current, the warm current will not reach the poles, which will easily lead to an ice age. The present earth is a good example.

The current ice age began 34 million years ago, marked by the appearance of ice sheets on the Antarctic continent. The appearance of ice sheets in the polar regions means that the global temperature has dropped, which means that something important must have happened on the earth.

Then the great event that caused this cooling was the Himalayan orogeny 40 million years ago. We all know that the Qinghai-Tibet Plateau and the Himalayas were caused by the compression and uplift of the Indian plate and the Eurasian plate. At that time, the Indian plate continued to drift northward, with one end hitting the bottom of the Eurasian plate and abruptly crashing out of the Qinghai-Tibet Plateau. It turned out that this piece was still along the coast and directly turned into an inland plateau. Even now, the Indian plate still arches northward, about 5 cm per year.

So back to the question of climate change, how does this large-scale orogeny affect the global climate?

In fact, after all, it has something to do with greenhouse gases. The Indian plate pushed the Eurasian plate, resulting in a large number of fresh rocks exposed to the atmosphere. Fresh rocks will be weathered in the atmosphere and consume carbon dioxide in the atmosphere. Because the Qinghai-Tibet Plateau and the Himalayas are too big, the content of carbon dioxide in the atmosphere has dropped a lot, and greenhouse gases have also begun to decrease, which means that the earth will begin to cool down.

The Himalayan collision can be said to have started this ice age, and the subsequent plate movement further aggravated the formation of the ice age.

Just now, we mentioned that if the warm ocean current from the equatorial region cannot flow to the polar region, glaciers will easily appear in the polar region. You can look at the current Arctic, which is basically surrounded by Eurasia and America. There are only a few relatively narrow passages connecting the Pacific Ocean and the Atlantic Ocean, which makes it difficult for warm ocean currents to enter the Arctic region.

Look at Antarctica. After the disintegration of Pangu, the Antarctic continent drifted south and finally broke up with South America 23 million years ago. Drake Strait appeared between them. As soon as the Derette Strait was opened, the Antarctic circulation was formed, which was equivalent to completely separating the warm water in the Antarctic. Since then, the glacier area in the Antarctic continent has become larger and larger.

The original terrestrial ecosystem was finally completely covered under the ice.

How should the earth get out of the ice age? If the earth wants to get out of the ice age, it is nothing more than increasing the content of greenhouse gases. For the first five glaciers, it is covered by a large area of glaciers, resulting in fewer plants for photosynthesis, thus reducing the consumption of carbon dioxide. Then, it is waiting for the volcanic eruption to replenish greenhouse gases to the atmosphere, and the accumulated greenhouse effect appears, and the earth is warming.

Simply put, it is two points: open source and throttling. On the one hand, we should destroy vegetation; on the other hand, we should emit more carbon dioxide.

Speaking of which, are you a little confused? Destroy vegetation and emit carbon dioxide. Isn't that what human beings are doing now?

Is all mankind has done just to get the earth out of the ice age? And compared with previous times, human beings are simply dead.

It took millions or even tens of millions of years for glaciers to slowly cover and get out of the ice age, but the speed of human destruction is much faster, because humans only need 10000 years to see the effect initially, and humans are better at emitting carbon dioxide. Humans directly dig out all the oil, natural gas and coal, ignite and burn them. As a result, the permanent glaciers on the earth have begun to melt.

So from this point of view, although human beings don't know what the ice age means to the earth, it is undeniable that human beings seem to be helping the earth out of the ice age, and higher creatures like human beings have been bred on the earth. Is this the reason?

The consequences of glacier disappearance.

Global warming is definitely a catastrophic event for human beings. If the earth comes out of the ice age, that is to say, all the permanent glaciers on the earth melt, the sea level will rise by about 70 meters.

This is absolutely devastating to human coastal cities. In addition, if the Himalayan glaciers melt completely, it will definitely lead to huge floods. These are all real impacts on human beings, so it will cost a lot to get out of the ice age. On the other hand, even if humans don't want to get out of the ice age, a lot of carbon emissions are inevitable at the current stage of human development. Even if they are controlled, they will only delay the process of global warming.

And now the polar permafrost has begun to melt, which will lead to microbial decomposition of frozen plant remains frozen in permafrost, thus releasing greenhouse gases such as carbon dioxide and methane into the atmosphere, which will further warm the earth.

This positive feedback warming process is irreversible. Since it is irreversible, on the bright side, the melting of permanent glaciers may reveal many unknown secrets to mankind.

For example, the discovery of frozen mammoths on the Arctic ground makes it possible for human beings to resurrect mammoths through cloning technology. Of course, for many reasons, this matter cannot be tried easily.

In addition to the permafrost in the Arctic, we should not forget the glaciers in the Antarctic continent. We should know that 65.438+0.6 billion years ago, the Antarctic continent was connected with other continents, the climate was warm and humid, and the ecosystem of the Antarctic continent was also full of vitality. So what do you think will be frozen under the glaciers of 65.438+0.00 million square kilometers?

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