Today, we will talk about the climate history of the earth. If we only consider the problem from the perspective of hot and cold, we will find very contradictory places. Last winter was very cold, but this winter is very warm, especially in the south of China. Last year's winter was cold and wet, and today's winter is warm as spring. The climate of the earth seems to be hot and cold. So, is it global warming or global cooling? In fact, when we discuss global climate change, we often confuse these two concepts. The weather is different from the climate. We can't regard the weather as climate. At the same time, climate change also has long-term, medium-term and short-term changes.

earth

First: Gaia hypothesis.

The earth itself has a very strong ability to repair itself, so now some scientists think that the earth does not need human rescue, but human needs to save its own civilization. Why do you say that? In fact, our earth itself is evolving. The history of life on the earth and the history of the earth itself are not two unrelated stories, but urgently connected stories.

The biosphere of the earth can be regarded as a huge organism, which scientists call Gaia, which is the name of the goddess of the earth in ancient Greek mythology. The theory of "Gaia Hypothesis" is simply that the earth's biosphere has the function of self-regulation, making the earth more livable. The whole biosphere of the earth is a whole, which can be considered as a super giant organism. The theory of "Gaia hypothesis" was first put forward by James Le flock in 1972, but it was not recognized by the mainstream scientific community at that time. Later, with computer simulation, people believed the truth of Gaia Hypothesis even more.

The biosphere of the earth is a super creature.

When we look for life in the universe, we often put forward the view of "livable zone" In a planetary system, the geographical position of the planet from the star should be moderate, and the temperature should not be too high or too low. However, this statement is actually wrong. The distance between the planet and the star is not important. The livable zone of the solar system is between 0.725 and 3.0 astronomical units, and 1 astronomical unit refers to the average distance from the earth to the sun. Planets in the habitable zone of the solar system include not only the earth, but also the moon, Mars, Ceres and Venus. The size of the Moon and Ceres is too small for gravity to hold the atmosphere. Mars and Venus are the most likely places for life. However, the environments of Mars and Venus are not suitable for life.

Even if the earth is in the best geographical position, the heat of the sun has changed. The heat of the sun has increased by 40% in 4.6 billion years, while the average temperature of our earth has been stable for 4.6 billion years. Now the average temperature of the earth's surface is about 65438 05℃. The constant temperature of the earth lies in the self-regulation of living things.

Venus and the Earth

Second: Global warming is nothing new.

At first, the earth was very unfriendly to life. Today, if we go back to the Phanerozoic earth (4.6 billion years ago to 3.8 billion years ago), we will feel that the environment here is very similar to Venus today, with hot magma everywhere and high-density carbon dioxide in the atmosphere. The earth and moon in Phanerozoic period are slowly cooling down. At that time, the surface temperature of the earth was around 230℃. If the temperature on the earth was 650℃, the atmospheric pressure was much higher than now because the concentration of carbon dioxide was particularly high. The higher the atmospheric pressure, the higher the boiling point of water, so liquid water existed. If we want to say that the global climate is warming, the temperature of the earth in Phanerozoic period is the highest.

The surface of the earth in Phanerozoic period was like Venus today.

The earliest life on earth appeared in Archean 3.5 billion years ago. Although the Archean surface temperature is lower than Phanerozoic, and the concentration of carbon dioxide is also lower (the ocean has the function of dissolving carbon dioxide), it is not suitable for the survival of most multicellular organisms on earth today. At that time, the earth environment was only suitable for bacteria to survive.

The earth has been a bacterial age for a long time in Archean. The earliest bacteria are archaea, which live on the seabed or near the submarine crater. They make a living by absorbing chemicals on the surface of the earth, and their energy comes from the temperature and chemicals on the surface of the earth. These archaea still exist on the earth today, and most of them live near submarine craters or hot springs. The environment here is in a high temperature state.

The archaea of the earth still lives in hot springs.

During the Archean period (4 billion years ago to 2.5 billion years ago), the oxygen content of the earth was very low, and the carbon dioxide concentration was particularly high. At that time, the earth was full of vitality. However, we must observe this vibrant world with a microscope. Life in this period was mainly bacteria. The environment here is very suitable for the survival of bacteria and single-celled organisms, but it is not suitable for the survival of humans and mammals because of insufficient oxygen.

We humans get energy not only by eating food and drinking water, but also by inhaling oxygen. Animals can eat and drink for a day, but they can't live without oxygen for a moment. It is very uncomfortable for us humans to stop breathing for 30 seconds. Obviously, oxygen is more important than food. With oxygen, we humans can walk and run and birds can fly in the sky. Without oxygen, life on earth will stay in the stage of bacteria forever, and there can be no multicellular organisms, because multicellular organisms consume a lot of energy. The activity of oxygen, we can also know through simple experiments that if we burn a match in an oxygen cylinder, the flame of the match will be particularly bright, which is the energy contained in oxygen. If the oxygen content in our earth's atmosphere increases a little, there will be mosquitoes and cockroaches one meter long on the earth.

Multicellular organisms cannot live without oxygen for a moment.

The increase of oxygen is due to the emergence of a kind of bacteria called "cyanobacteria", whose cells are rich in chlorophyll molecules and can carry out photosynthesis. Bacteria on the earth used to survive by absorbing the heat of the earth itself. Later, a kind of bacteria began to try to use the energy of the sun, so cyanobacteria appeared, which is what we know now. If the water in the pond is stagnant, it won't take long for a layer of green creatures to float. These creatures are cyanobacteria, but they are not plants, but bacteria.

In more than 2 billion years, cyanobacteria absorbed a lot of carbon dioxide and produced a lot of oxygen. With the decrease of carbon dioxide concentration, the temperature of the earth began to slowly decrease, becoming suitable for the survival of multicellular organisms. However, oxygen-rich atmosphere is harmful to bacteria. On our earth, on our bodies, there are a lot of anaerobic bacteria. These bacteria hate oxygen, which is a "killer" for them. Anaerobic bacteria cannot be exposed to the air, so it is very difficult to survive in the air. They can only exist in places without oxygen, in some parts of our intestines and mouth, where there is no oxygen. So these anaerobic bacteria breed in these suitable places for their survival.

Microscopic cyanobacteria, cyanobacteria are actually bacteria.

So the appearance of oxygen killed a large number of bacteria on the earth, leaving a vacant niche, from which multicellular animals evolved. However, bacteria are not completely extinct, and some bacteria still exist. They breed in every corner of the earth and remain the most diverse creatures on earth. Anaerobic bacteria live in oxygen-deficient places, and some bacteria adapt to oxygen-rich atmosphere, which is oxygen-absorbing bacteria. Anaerobic bacteria can't live in oxygen-rich places because they lack a complex metabolic system and can't get energy through oxygen, but through fermentation and photosynthesis. Obviously, this way of obtaining energy is very inefficient, that is to say, in an oxygen-deficient atmosphere, you can't find multicellular animals like tigers, lions and humans, and the inefficient way of obtaining energy is not enough to support a huge body.

The appearance of oxygen also promotes the formation of ozone layer, which can block ultraviolet rays. Without the ozone layer, the earth's land is not suitable for life, and life is in the ocean. The formation of the ozone layer creates conditions for life to land.

Looking back at the brief history of life on earth, we can't find that the biosphere of the earth is also evolving. It is life on earth that makes the earth more livable, rather than a single species on earth relying on heredity and variation to adapt to the earth's environment.

Of course, the realization of this cooperative relationship in the whole biosphere comes from the biological phenomenon of * * *.

Third: the ability of the earth to repair itself.

Because the earth's biosphere itself is a superorganism, when we humans destroy the ecological environment of a place, the ecological environment of this place can be self-repaired. For example, we have built a large number of reinforced concrete tall buildings and built cement roads, which makes the urban environment unsuitable for the growth of plants and the survival of wild animals. However, if we humans leave the city at once, in a few years, plants will occupy the city, plants will take root in the cracks in the walls, and in order to compete for sunlight, plants will gradually grow all over the walls until the roof. With the development of plant roots, walls will loosen and tall buildings will collapse, becoming broken walls. After plants occupy the city, wild animals will slowly enter the city, and finally, the city will return to the state of virgin forest.

There are often many wild animals and plants in inaccessible places.

What happens here when humans leave a city? In fact, there are examples in world history. After the Chernobyl nuclear accident, mankind suddenly evacuated from Chernobyl and its nearby cities and villages, and designated isolation zones. A few years later, the buildings here were submerged in the forest and became a paradise for wildlife. Swans, brown bears, European bison, elk, wild boar and wolves have come here to settle down. Although there is nuclear radiation here, it is not suitable for human survival, but animals live well here. They seem to have adapted to the environment here, and there is no obvious evidence that the animals here have genetic mutations. This is the self-repairing ability of nature. In ancient world history, some ancient cities were abandoned for various reasons. With the passage of time, the walls and buildings of these ancient cities have also been submerged in weeds and forests.

Chernobyl, which is about to be occupied by plants

We humans actually don't need to save the earth, and we have no ability to save the earth. As long as we stop destroying the ecological environment of the earth, the ecological environment of the earth will gradually recover. If you really want to protect the ecological environment of a place, you should set up a nature reserve here and leave this place. Without human interference, the ecological environment here will become very beautiful and become a paradise for wild animals.

So, so is global warming. The earth has the ability to self-repair the ecological environment, which is very powerful and beyond human imagination. Since the industrial revolution, human beings have increased carbon dioxide emissions, leading to an increase in the global average temperature. However, the emission of greenhouse gases is only one of many factors that affect climate change. It changes a variable, and it will not absolutely lead to whether the climate will become cold or change tomorrow. The earth itself is also adapting to this change and repairing the ecological environment.

Gaia hypothesis shows the importance of self-improvement and self-regulation of the earth's biosphere. In the long years of the earth, not only can human beings increase the concentration of carbon dioxide in the atmosphere, but also the geological movement of the earth itself will change the oxygen content and carbon dioxide content of the earth's atmosphere.

There have been six mass extinctions in the history of the earth, of which the late Devonian (375 million years ago to 360 million years ago) and the Permian-Triassic mass extinctions (250 million years ago) were all caused by the change of oxygen content in the atmosphere.

The late Devonian extinction occurred because in Devonian (from 350 million years ago to 465.438 billion years ago), plants on the earth began to land on a large scale, green plants expanded in the terrestrial ecosystem on a large scale, and the bare surface began to be covered by dense forests. The emergence of terrestrial forest system has changed the composition of the earth's atmosphere, and plants have produced a lot of oxygen and absorbed a lot of carbon dioxide. Due to the reduction of greenhouse gases,

Devonian plants

After plants enter the land, their roots will also lead to rock differentiation. Under the action of rain, a lot of nutrients in the soil are brought into the ocean. When there are more nutrients in the ocean, eutrophication will occur, and a large number of plankton will grow wildly, absorbing oxygen in the ocean, resulting in hypoxia in the ocean and the extinction of a large number of marine animals. Regarding this phenomenon, we can also see on today's earth that human beings unreasonably discharge sewage, which leads to the excess of nutrients in natural water bodies and the massive growth of plankton. Finally, the ecological environment of the whole lake deteriorated rapidly, and a large number of aquatic animals and plants died.

Where did the carbon dioxide absorbed by Devonian plants go? When carbon in carbon dioxide solidifies into plants, coal is formed. Devonian is a period when a large amount of coal was formed. Now, we humans have dug up all the coal and burned it. The carbon absorbed by Devonian plants is released by us. This is global warming.

Although there was a mass extinction event in the late Devonian, with the passage of time, our earth was readjusted and life on the earth flourished again.

By the Permian-Triassic period 250 million years ago, another mass extinction event occurred on the earth, which was mainly caused by the increase of greenhouse gases such as carbon dioxide and methane. It was reduced last time and increased this time. Why did the greenhouse gases on the earth suddenly increase 250 million years ago? Because during this period, the most violent volcanic eruption occurred on the earth, which was called "Siberian basalt volcanic eruption" in history. This volcanic eruption lasted for more than/kloc-0.0 million years, and we can still find the evidence left by the large-scale volcanic eruption in Siberia today.

The eruption of Siberian volcano led to a large amount of carbon dioxide emission, which triggered a chain reaction. With the increase of the earth's temperature, the seawater temperature in the shallow sea area adjacent to the volcano also increases, and a large number of combustible ice melts. Combustible ice is rich in methane gas, which is a more serious greenhouse gas than carbon dioxide. After a large increase in methane gas, the earth's temperature continues to rise, which eventually leads to the melting of deep-sea combustible ice, further increase in temperature, and the extinction of a large number of animals on the earth.

Therefore, the earth went through hot water, but finally it returned to normal by the self-repair ability of the biosphere, maintaining a constant temperature of 15℃.

Looking back at the history of the earth, we find that the current global warming is nothing compared with the global climate change during the geological period. But does this mean that humans can emit greenhouse gases on a large scale? The answer is no!

Excessive emission of greenhouse gases will lead to the increase of the earth's temperature and the occurrence of biological extinction. However, the earth will not perish, nor will living things. Extinct species will never appear again, and dinosaurs will never come to earth. Even after the extinction of dinosaurs, life on earth will flourish again, but there will be no single species, that is, evolution will not reset. If we artificially change the climate of the earth, then it is not our human species that will be impacted first, but human civilization, which will be the first to be impacted. Once human civilization collapses, we can't survive if we go back to the forest. As a species, human beings may disappear from the earth.

Triassic laterite proved that the temperature was very high at that time.

Once humans disappear from the earth, plants will occupy cities and villages. Under the self-regulation of the earth's ecosystem, forests will flourish again, the content of carbon dioxide will be reduced, and the temperature of the earth will gradually drop, making it suitable for living things again. However, we humans no longer exist, and evolution will not come back.

Therefore, if greenhouse gases are artificially and excessively emitted, the global climate will not become cold or hot, but extreme weather and drastic climate changes will occur. Once human civilization cannot withstand such drastic changes, our survival will be threatened. Now on the earth, in some places, winter is often cold and hot, which is precisely the reflection of this drastic and extreme change. What we humans should worry about is not whether it will get cold or hot tomorrow. It doesn't matter whether it is cold or hot. What matters is whether our civilization can withstand extreme and drastic climate change. The simplest example is that extreme weather such as typhoon, snowstorm and tornado will cause huge economic losses. Then, will man-made climate change lead to extreme weather worse than typhoons and blizzards? Actually, it is possible. This is the "new fairy wood event" that happened in the history of the earth.

The specific content of the "New Fairy Tree Incident" is limited to space, so I won't go into details. 13000 years ago, the climate on the earth was warm, much warmer than it is now. At this time, mankind was in the late Neolithic period. As the temperature rises slowly, glaciers in the Arctic and Greenland begin to melt in large quantities. After the glacier melted, a large amount of fresh water was injected into the North Atlantic to block it.

Melting Arctic glaciers may lead to global climate cooling.

We all know that warm current can increase temperature and humidity, and cold current can decrease temperature and humidity. After the North Atlantic warm current stops flowing, the heat in the low latitudes of the earth cannot be brought to the high latitudes through the North Atlantic warm current. As a result, severe temperature drop and large-scale glacier expansion occurred in North America and Western Europe. The earth ushered in a cold period. The temperature at that time was even colder than now. With the decrease of the number of animals and plants, human beings are forced to start agriculture, from food gatherers to food producers. It was 6.5438+200,000 years ago that mankind invented agriculture. At first, people lived in the forest without food and clothes. After food shortage, human beings were forced to engage in agriculture. So global warming may not necessarily lead to an increase in temperature, but may lead to a decrease in temperature. Now that the global temperature is rising, polar glaciers are melting, and a large amount of fresh water is injected into the North Atlantic, will it lead to the interruption of the North Atlantic warm current? This is a question worth thinking about.

We protect the environment, in fact, not the earth, but ourselves, for the sustainable development of human civilization. When we understand this, we don't have to worry about whether the global climate is getting cold or hot. Destroying the ecological environment and polluting the environment will eventually make our human civilization unable to withstand such drastic changes. You know, man-made changes to the earth's ecological environment are much faster than natural changes.

Protecting the ecological environment and reducing carbon emissions are actually improving our scientific and technological level. Even if the global climate is not warming, we have reduced carbon emissions and reduced our dependence on fossil energy. Finally, it is human beings who benefit. Therefore, we don't need to save the earth, but we should save ourselves and our civilization and technology.