Scientist: The cooling rate of the earth’s interior is far faster than expected

Earth is a beautiful planet on which human beings live, and we call it “Mother Earth“. It has existed in the solar system for 4.5 billion years, and has undergone hundreds of millions of years of geological evolution, so that the earth has the environment suitable for human habitation today. Human beings, such advanced intelligent beings, can exist because the earth has evolved a suitable environment. Is the earth still healthy?

There seems to be some problems in the interior of the earth, making the earth somewhat “sub-healthy“. What’s the problem? The Earth’s interior is slowly cooling.

The Earth is getting colder

To explain the cause of cooling, you need to know these questions: What are the components of the Earth’s interior? The Earth’s interior is cooling faster and faster, what is going on? If the core of the Earth were cooled, what would be the impact on humanity? The journey of demystification is about to begin.

The Earth’s core is cooling far faster than expected, and to find out why, let’s start with the Earth’s internal structure.

The structure of the Earth’s interior

The structure of the Earth’s interior

The earth’s interior is the core, and the core is divided into the inland core and the foreign core, and the depth of the outer core is defined at 2900km to 5000km, and the internal nuclear depth is 5100km to 6371km. There is also a transition zone between the inner and outer cores, with a depth of 4980-5120 km underground. The field nucleus is mainly composed of liquid iron and nickel, with 15% silicon, sulfur, hydrogen, oxygen, potassium and 10% nickel. This flowing nickel-iron alloy can easily achieve extension and deformation, generating and maintaining the normal operation of the Earth’s magnetic field.

core

The inland core has a pressure effect of millions of atmospherescompressing the iron and nickel elements in the inland core into a solid state. It should be known that the temperature of the inland core is as high as 7200 °, but the melting point of iron is only 1535 °C, and the melting point of nickel is 1455 °C. If there is no extrusion of the ultra-high pressure of the inland core, the alloy material in the form of iron and nickel is still a flowing liquid.

The earth’s core volume accounts for 16.2% of the entire earth’s volume, and the mass accounts for 31.5% of the entire earth’s mass. In general, the core of the Earth is the core part of the Earth, with a radius of about 3470 km, and is a high-density (about 10.7 g/cm³) material composed of iron, nickel and other elements.

Earth tectonics

Above the core is the mantle, and above the mantle is the crust. If the earth is compared to a raw egg, then the core of the earth is equivalent to the yolk, the essence of the “egg” of the earth, the mantle volume is the largest, it is equivalent to the egg protein, wrapped around the core.

The outermost layer of the Earth’s sphere structure is the Earth’s crust, which is equivalent to the eggshell of an egg, and the “eggshell” of the Earth is between 3 and 12 kilometers thick, with an average thickness of 7 kilometers. So you can imagine the thickness of the mantle, the core, and if you can’t conceive it in your mind, you can use eggs.

Mantle construction

After understanding the unobservable internal structure of the earth, it is finally known that the core of the earth is iron and nickel, maintaining a very high temperature, showing liquid and nearly solid properties. However, studies have shown that the Earth’s interior is cooling at an unexpected rate. Will the earth gradually change from a warm planet to a cold, icy place?

Accelerate the cooling of the Earth

Scientist: The cooling rate of the earth's interior is far faster than expected, is the earth going to be "cool"?

Cooling Earth

The Earth we live on is actually an aging planet, it has been born for 4.5 billion years, the Earth’s interior transfers heat to the surface, drives mantle convection, and completes the geological structure, which has an important shaping effect on the early Earth’s form. But the heat inside the earth is not inexhaustible, just like the earth’s fossil fuel resources, which are limited and non-renewable.

So the “reactor” inside the earth will gradually cool down over time, we know the principle of heat transfer, in solids, liquids, gases, due to temperature differences, heat will be transferred from high temperature substances to low temperature substances. Heat transfer includes heat conduction, thermal radiation, and thermal convection.

Heat conduction

Heat transfer is mainly the way in which solid heat transfer occurs, and thermal radiation is the transmitting of radiant heat energy to the surrounding area by an object relying on its own temperature Thermal convection is a phenomenon that is directed at fluids and the motion of microscopic particles of fluids. The core of the earth needs to pass through the mantle and through the crust to reach the surface of the earth, and the mantle is the largest part of the “egg” of the earth. The main components of the mantle are oxides and minerals formed by various elements, and scientists mainly judge the rate of heat loss in the earth’s interior from the study of minerals in the mantle.

Research materials on bridgeman rocks

Geologists and astronomers have explored in the past how a boundary mineral called Bridgeman Rock conducts heat from the core to the surface. They placed the cut single crystal Bridgeman stone on a base made of diamond, tested the thermal conductivity of the Bridgeman rock by laser heating, and found that it was 1.5 times higher than the hypothesis. This means that heat is transferred from the Earth’s core to the mantle at a higher rate than originally assumed. The increased convective motion in the mantle causes the Earth’s cooling rate to accelerate.

Schematic diagram of long-term changes in stable phase and thermal conductivity in the nuclear mantle boundary region

Bridgeman rock is a mantle boundary rock whose thermal conductivity increases rapidly with the change of nature, because when the local mantle boundary cools to a certain value, the Bridgeman rock will be converted into post-perovskite. In the academic report of Chinese scholar Jin Zhenmin on post-perovskite, he said that the discovery of post-perovskite has played an extremely important role in promoting geophysics and high-pressure mineral physics.

This mineral can maintain structural stability under extreme conditions and is an effective substance to promote the direct competition between photovoltaic products and crystalline silicon. It is believed that this amazing mineral can promote greater progress in geophysics research.

Molecular structure of perovskites

Although bridgeman rock has better thermal conductivity after conversion into post-perovskite, it will also lead to a further acceleration of the cooling rate of the Earth’s core, which is not a good thing for the Earth.

If, we mean, if the earth’s core really cools down on a certain day, what kind of impact will it have on the earth and the people who live on it?

Scientist: The cooling rate of the earth's interior is far faster than expected, is the earth going to be "cool"?

The Earth cools

The hypothetical of kernel cooling

The cooling of the Earth’s core means that the movement of the Earth’s core of liquid ferro-nickel alloys and solid ferro-nickel alloys is completely static, and the Earth’s magnetic field will disappear. The magnetic field is the source of the stable and orderly structure of the Earth’s interior and the basis for the Earth’s gravitational pull.

The magnetic field has the effect of protecting the earth from various radiation interference and effects, and its properties are like a huge barrier, capable of causing the deflection of charged particles from the sun, avoiding the atmosphere and life that live on the earth’s surface Bombarded by these high-energy charged particles.

The Earth’s magnetic field protects it from being bombarded by solar particles

If the earth’s core cools and the magnetic field disappears, the earth will probably become a second Mars, a dead and desolate planet.

The disappearance of the magnetic field means that species on Earth will be harmed by large amounts of space radiation and cosmic rays, especially the solar wind, which releases high-energy charged particles and ions. So how does the solar wind affect the Planet? The solar wind is constantly spreading outwards, and the solar wind that reaches the Earth first affects the atmosphere that has lost its magnetic protection.

The surface of Mars

The atmosphere will be drained little by little, followed by a large amount of evaporation of liquid water, and a large amount of liquid water on Earth will escape into space in the form of water vapor. You know, 71% of the earth’s surface area is oceans, about 360 million square kilometers, and the earth has about 1.386 billion cubic kilometers of water, which will all become the aimless water vapor in space. Without water, the Earth would be a lifeless planet with a large number of dead creatures, just like Mars today.

Earth from a Martian perspective

Speaking of Mars, mars in the past few billion years actually has great similarities with Earth: there is liquid water and a rich atmospheric environment, but in the long heat divergence, the core of Mars began to cool from hot With the dissipation of energy, the magnetic field gradually disappears, and Mars becomes a planet with no temperature and no life.

However, we do not have to worry about the situation of the earth, the earth’s interior contains rich thermal energy, stored in the core and mantle rich in ferronic alloys, the geological tectonic movement and volcanic earthquakes on the earth such geological disasters, from the earth’s internal energy 。 The cooling of the Earth’s core means that geological activity gradually calms down from the active state of volcanic eruptions and earthquakes, and geological disasters will be reduced. This is a good thing for the human living environment.

Volcanic eruptions

In general, although the Core of the Earth has accelerated cooling in the observations of scientists, it is only a small numerical change, and the Earth is also receiving solar radiation and atmospheric reverse radiation in addition to the heat emitted inside. The lifespan of the sun is about 10 billion years, and now the sun has a lifespan of 5 billion years, and the earth has about 4.6 billion years, so Taiyang is more “long-lived” than the earthand can provide the light and heat needed by the earth during its lifetime.

The current temperature of the earth is stable, and the mantle and the inner and outer cores are like layers of insulated cups to protect the energy of the earth’s core, and in the next few hundred million years, more than one billion years, the earth’s internal energy will still be maintained at a high level 

Earth heat

Protect Mother Earth

Every year on April 22 is World Earth Day, and this special holiday is set up to protect the global environment, arouse the public’s attention to environmental issues, and call on more people to participate in environmental protection. We have always emphasized low-carbon environmental protection, which needs to start from the details of life.

Earth Day

Now we have implemented stricter garbage classification standards, with the aim of implementing environmental protection and improving the recycling rate of resources. The education we received from childhood is to save water, save electricity, use less disposable products, and the awareness of environmental protection has been cultivated from an early age, but there are very few people who can practice life, so it is very important not to forget the original intention and implement the concept of environmental protection.

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