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Home page > 02 - Livre Deux : SCIENCES > Géodynamique et climatologie de la Terre - Protection de la planète > It is the core of the Earth that warms our planet and not the atmospheric (...)

It is the core of the Earth that warms our planet and not the atmospheric greenhouse effect

Tuesday 29 October 2019, by Robert Paris

The temperature of the earth’s inner core increases

The regions of the poles where ice melts are those where volcanoes are under the ice



North Pole

It is the core of the Earth that warms our planet and not the atmospheric greenhouse effect

Warning: we present here a new thesis of some scientists, which has not yet had the time to be confirmed or invalidated, and which completely changes our point of view on the nucleus of the Earth. This would not only be warmed by the gravitational concentration of nuclear-heavy and unstable atoms, which would warm it by radioactive decompositions of these unstable nuclei, but also the seat of fissions developing exponentially, in the manner of a natural and spontaneous nuclear power plant.

Why is there more and more volcanism, earthquakes, and warmer soil? Not because of the greenhouse effect but because the core of the earth is warming up by heat accumulation related to radioactive fissions in the center of the planet.

What do we know about the Earth’s core?

The center of the Earth is a gigantic core of 2,400 km in diameter (5,150 km from the surface). It is composed of iron and trace elements. It is the "inner core" (or "seed" of solid iron). The temperature is 6000 ° C. The pressure is 3,600,000 times stronger than at the surface. Subject to these pressures and extreme temperatures, iron would adopt the heart of our planet, like the diamond, a crystal structure.

This seed bathes in an immense ocean of molten iron, the outer core. Huge vortices in this liquid (convection currents) would generate the magnetic field. The instability of these vortices would cause the modifications of the magnetic field.

Let us first remark that we have no means of direct measurement of the temperature of the Earth’s core, and that the only temperatures recognized are by indirect reasonings which give divergent results:

see here

Between 3800 and 5500 for some, 6500 for others, the temperature of the Earth’s core is not really known ... Probably as hot as the surface of the sun!

CEA researchers have just shown that the temperature in the center of the Earth was significantly higher than the values allowed so far.

To calculate this temperature more precisely, the researchers subjected an iron sample to the extreme physico-chemical and thermal conditions that reign in the heart of the Earth, in the Earth’s core located at a depth of 2900 km.

So far experimental results and theoretical predictions of core temperature have been at odds. To resolve this discrepancy, researchers compressed tiny iron grains between two diamond points, reaching a pressure of two million atmospheres. In parallel, these iron particles were heated with a laser beam.

Using the X-ray source of the European Synchrotron, the researchers managed to measure the physical evolution of the iron particles up to a pressure of 2.2 million atmospheres and a temperature of 4800 ° C.

By extrapolation, scientists were able to calculate that at the pressure in the core - 3.3 million atmospheres, the temperature of the iron was to reach about 6000 ° C, which is in agreement with the theoretical predictions.

The researchers of CEA and CNRS, whose work was published last month in "Science." How, in the absence of a direct means of measurement, estimate the temperature that reigns deep in the Earth’s core, this area constituted essentially A clue: this nucleus itself has a nucleus, called the seed, also made up of iron, but in the solid state.This seed grows very slowly by solidification of the surrounding liquid nucleus. core-seed boundary, at a depth of 5.150 kilometers and with a pressure corresponding to 3.3 million times that of the atmosphere, the temperature must therefore be close to that of melting iron at this pressure. , the researchers compressed tiny iron grains between two diamond points (in order to recreate this gigantic pressure) while gradually heating them with a laser beam. At what temperature did the iron grains change from the solid state to the liquid state, which could only be done indirectly by bombarding them with X-rays. The result is in 4 digits: 6.000 ° C.

But does this temperature come from a balance or an increase? What dynamics does it follow?

It is the nucleus of the Earth, whose radioactive materials emit nuclear energy, energy that tries hard to emerge through the magma and then the earth’s crust, which warms the planet and not the atmospheric greenhouse effect.

As bizarre as it may seem, we know more about distant stars and galaxies than about what happens in the center of the Earth, in the molten nucleus. The theorists diverge fundamentally both on the operation of this nucleus, on its dynamics, on its characteristics: pressure, temperature, magnetism, etc ... As we have never been able to record the evolution of this nucleus, impossible for the moment. to be sure of how this core is evolving, especially how its temperature is changing.

What is known is that the heat of this heart does not come from that of the molten materials at the origin of the Earth, energy exhausted for a long time on the surface as in depth. It is known that it is the spontaneous nuclear decompositions of uranium, thorium and potassium atoms, long-lived radioactive elements, which emit nuclear energy, increasing the temperature and merging the nucleus to the point that it would be a temperature equivalent to that of the surface of the stars, which is not nothing: several thousand degrees !!!!

On the other hand, the evolution of the production of this energy depends on the part of each of the radioactive elements because they do not have the same lifespan, the uranium thus being faster to decompose. For example, potassium should be known to estimate whether it is possible for the nucleus to heat up or cool down. And again it depends on the type of uranium: the half-life of uranium 235 is 700 million years while that of uranium 238 is 4.5 Ga!

But all this does not tell us what is the temperature finally and the numbers cited by the scientists vary considerably between 5000 and 7000 degrees ... As to reflect on the evolution of this temperature, one does not fix it easily, considering the difficulty to measure, directly or indirectly, anything.

The only way to reason about this heart of the planet was to discuss the pressures that can prevail and the states of matter of this nucleus, by discussing the temperatures that this implies. A very indirect discussion that certainly does not allow to discuss changes in the temperatures of this Earth’s core.

Let us first recall that the term terrestrial core means an internal ball with a radius of 1220 kilometers which is actually unknown in what state of matter it exists (solid, liquid, plasma, ...). How many different layers of this nucleus, in what states are they, all this is still under discussion, and the debates are far from being settled.

One of the elements of the debate is the existence of a magnetism induced by this terrestrial nucleus which contains a considerable part of iron. This assumes that the iron core undergoes a rotation that produces the internal field of the Earth ... Indeed, it is impossible for the iron to maintain a permanent magnetization at high temperatures that far exceed the threshold: Curie point. It is therefore necessary that the ferrous core be surrounded by molten iron and produce a magnet effect self-maintained by a dynamo mechanism due to the rotation of the solid core in the liquid. It also involves high temperatures to keep the iron melting despite enormous pressures ... But all of this also depends on the size of the solid core. Is it constant? What determines it is the temperature. If the heat accumulates in the center, the nucleus melts and diminishes, modifying the speed of the movement of the solid nucleus and the magnetic effect produced. This is what seems to happen ... What decides on it is both the state of the radioactive fissions, the percentage of unstable nuclei that decompose and the ability of the heat to escape to the surface via the coat and the crust ...

What energy has managed to feed the Earth’s magnetic field, knowing that it has existed for 3.2 billion years while the solid seed would exist only for 2 billion years maximum (taking into account the cooling of the ball in original fusion)? It would be necessary that one finds in the terrestrial core also radioactive potassium, which would also explain the current warming by the natural radioactive decays in the nucleus ...

Do we have reason to believe that global warming originated in the core of the planet?

One of the reasons is that the phenomena whose origin is the heat of this nucleus seem more and more active: volcanism, terrestrial and submarine, earthquakes and tsunamis ... Again, the measurement of an evolution is not easy and it is difficult to say if the magmas of today are more active than those of yesterday ....

What relation, moreover, the warming of the Earth could have with the evolution of the temperature of the nucleus and its radioactive decompositions?

Well, it must first be noted that the areas from which these temperature increases start seem to be linked to the faults of the Earth’s crust through which the Earth’s internal heat finds its way outward.

One example is the volcanism of the North Polar Zone. It seems that the melting of Greenland does have a non-atmospheric origin but due to the increase of the underground temperatures related to the increase of the temperature of the nucleus ... Indeed, it turns out that the glacier melts underneath!

Another example is the zone of appearance of hot water masses within the Pacific, which gives rise periodically to the so-called "El Ninõ" phenomenon, which is attributed a significant part of global warming.

Let us first note that the origin of the start of episodes "El Niño" has been sought, unsuccessfully, in climatic causes (marine currents, changes of pressure or surface temperature, atmospheric movements and others ...). This means that its origin is neither on the surface of the Earth nor on a climatic basis. So it is indeed plate tectonics and magmatic movements, that is to say fundamentally changes or movements starting in the center of the Earth, that this phenomenon, which causes an increase in surface temperature, follows. If it is stronger than before, it is because the heat of the center of the Earth is also ...

What is the reason for the radioactive materials (nuclei of heavy and unstable atoms) in the center of the Earth emitting radiations and energy in a manner that is always the same, and why the heat of the center escapes to the surface consistently? Any ! It is quite possible for the center to lose more heat or to accumulate more heat. There is no physical reason to believe that the heat of the nucleus is in equilibrium nor that the dynamics of the nucleus are constantly equal to itself. There can be jolts, as evidenced by El Niño or slow changes over long periods, as evidenced by the increase in volcanoes and earthquakes or as evidenced by the rise in global temperature.

But, will you say, this rise has already found its reason with the increase of the gases with "greenhouse effect", carbon dioxide, steam and methane in particular?

It is not that simple. There is no direct evidence that this is the cause and there are many reasons to believe that this is not the case.

First reason: the greenhouse effect is limited in its effects and, beyond a threshold, the effect is reversed!

Second reason: there are other feedbacks of the atmosphere going in opposite directions, including the albedo which controls the return of light rays by the Earth.

Third reason: there are feedbacks related to the living, especially to marine microorganisms.

Fourth, the rise in temperatures far exceeds that predicted by the greenhouse effect, even with significant increases in carbon dioxide of human origin.

Fifth reason: the rise in temperatures that must be taken into account goes far beyond what is measured. Indeed, the measured temperature takes into account the decrease of the energy emitted by the Sun, since the Earth is in a period where it moves away from its last warming, following the "small ice age".

In sum, from the solar point of view, we would be in a phase of glaciation that is tempered by the rise in temperatures due to something other than the Sun and therefore due to something else than the greenhouse effect ... As a candidate, it does not remains more than the internal energy of the center of the Earth which, it is not necessarily declining and which depends on heavy elements, atoms with unstable nuclei and emitting nuclear energy.

And from the point of view of the nuclear fissions of the unstable nuclei, one can ask the question of where one is historically: is it possible that these fissions increase or that the energy accumulates in the interior of the Earth, incapable to extract enough to maintain a thermal balance of the nucleus? It’s perfectly possible!

A scientific calculation has given the following result: a one-degree increase in earth surface temperature can come from a 15-degree increase in core temperature.

Is there any way to know if the melting of the central core has increased due to a rise in temperature of the center? Yes, the solid nucleus that turns in the molten liquid would turn faster. Well, that seems to be the case !!!

It will already be noted that the mere fact that the center of the Earth has not yet cooled despite the rise of heat by the mantle already raises questions about the durability of the phenomenon and suggests that the energy of the core has been underestimated until the…

Conclusion: it could be that the center of the Earth is therefore warmer than we thought before ...

On the other hand, in the energy balance of the Earth, certainly the nucleus represents a relatively small number of kilometers compared to the mantle more to the Earth’s crust, it represents only 16% of the total volume but it represents 67% of the mass terrestrial, which is fundamental in terms of energy storage capacity!

Boehler, Reinhard. Melting temperature of the earth’s mantle and core: Earth’s thermal structure. Annual Review of Earth and Planetary Sciences 24.1 (1996): 15-40.

Anzellini, S., et al. Melting of Iron at Earth’s Inner Core Boundary Based on Fast X-ray Diffraction. Science 340.6131 (2013): 464-466.

The idea of a kind of nuclear reactor (of non-human origin) operating inside the Earth may seem absurd. Yet it is not ... There is indeed indisputable proof that the phenomenon is possible. In the Oklo uranium mine in the Gabonese Republic, the residues of a self-sustaining nuclear fission reaction that occurred in the rock about 1.7 billion years ago were found.

The discovery dates from June 1972, when it was found that some of the ore was abnormally poor in 235U. It was soon obvious, as later analyzes showed: for more than 400,000 years a series of small natural nuclear reactors had spontaneously started and then operated for long periods of time. Originally dispersed in sandstone, uranium 235 was found in some areas until the concentration needed to start the fission. The presence of water circulation moderated and allowed the chain reactions to occur slowly but stably.

In 1992, nuclear chemist Marvin Herndon proposed the existence of a natural nuclear reactor similar to Oklo’s in Jupiter and other giant planets. We know that these planets are more active than we thought and that they radiate more energy than they receive from the Sun. It is not certain that the simple Kelvin-Helmoltz mechanism of gravitational contraction, coupled with phase change processes, such as the condensation of helium, causes a sufficient release of energy for explain the observations.

Herndon then extended his ideas to the case of the Earth by imagining that the energy animating the convection currents in the nucleus was not due solely to the slow and continuous crystallization of the seed. Most geophysicists and geochemists remain skeptical, as it is hard to believe that the nucleus has been able to enrich itself sufficiently in radioactive elements. Indeed, depending on the mineralogical composition and physical conditions, some elements may or may not be associated in a rock.

A variant of this idea has just been relaunched by the physicist Rob de Meijer of the University of the Western Cape, Cape Town (South Africa) and the geochemist Wim van Westrenen of the Free University of Amsterdam. It would not be in the nucleus but in some areas at the base of the mantle, just above the core-mantle interface, that uranium may have accumulated to form natural nuclear reactors.

Both researchers rely on a recent discovery by Maud Boyet and Richard Carlson that the Earth’s mantle has differentiated more rapidly than previously thought. Based on the comparison of the abundances of 142Nd, a neodymium isotope, in terrestrial rocks and chondrites, this breakthrough in the history of the Early Earth implies that at the core-mantle boundary there should be a uranium-rich reservoir. thorium and potassium, long-lived radioactive elements that give off heat.

According to De Meijer and van Westrenen, uranium could easily accumulate in the calcium-rich perovskite found at the base of the mantle. The concentration to be achieved to obtain a chain reaction is still 20 times greater than what seems possible in this silicate but, in their opinion, the difference is not large enough to exclude that the phenomenon can occur there. Mantle nuclear reactors, if they exist, could even function as breeder reactors and produce plutonium. In addition, the reaction products would contain helium and xenon, which could explain anomalies found in the lavas rising to the surface at hot spots.

The mantle of the earth heats up because the core is warming up !!!

‘Global warming comes from within’–Is heat at the Earth’s core the real cause of global warming?

Although there is nothing wrong with the statement that the Earth is truly very hot at its center (actually as hot as the surface of the sun) the notion that it is a significant source of heat at the surface is easily dismissed with a little critical thinking. If the inner heat were really the dominant factor, then surely the day-night cycle would not be what it is, nor would you expect such variation in climates over seasons and latitudes. How can the south pole be covered with thousands of meters of ice with all this heat supposedly bubbling up from the surface? Why would a little lower angle of sunlight cause the average temperature to drop from +20°C in the summer to -20°C in the winter?

The fact of the matter is, solid rock is an extremely good insulator and the heat from the mantle propagates up very slowly and diminishes very quickly (at about 20°C/km) to almost nothing by the time it is at the surface. At the surface, the earth is releasing less than one-tenth of one Watt/m2. If you could somehow capture all of the energy coming up from the earth’s core into the foundation of an average-sized home, you might have enough to power one 15W light bulb! Not a lot of of juice when you compare it to the sun, which provides on average some 342W/m2 of energy to the earth’s surface.

And let’s not forget that what we are talking about is climate change, not just climate. So we need some kind of change in this heat flux if we wish to explain a change in the global temperature. Scientists have calculated that increased greenhouse gases have resulted in a radiative forcing of 2.43 Wm-2 which means we need that many Watts/m2 of change to account for the current warming. Back to geothermal, this means the energy flow from the earth would have had to jump by over 200 times to be the cause of the approximately 0.8°C temperature rise.

It is pretty hard to imagine not noticing that!

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Skeptic.

“Global Warming comes from within” is also posted on A Few Things Ill Considered, where additional comments can be found, and where the author, Coby Beck, is more likely to respond.


Are there nuclear reactors at Earth’s core?

Fission reactors may have been burning for billions of years.

Philip Ball

Nuclear reactors could be burning deep beneath the ground, two scientists have claimed. They say that uranium could become sufficiently concentrated at the base of Earth’s mantle to ignite self-sustained nuclear fission, as in a human-made reactor.

This is not the first time that natural ‘georeactors’ deep inside Earth have been proposed, and the idea has previously been greeted with scepticism by geoscientists. But physicist Rob de Meijer of the University of the Western Cape in Cape Town, South Africa, and geochemist Wim van Westrenen of the Free University of Amsterdam in the Netherlands, believe that their new proposal1 is more plausible.

Radioactive decay of unstable isotopes of heavy elements such as uranium happens all the time beneath Earth’s surface. The energy released contributes significantly to the heat of Earth’s mantle, which is also warmed by the planet’s molten iron core. This combined heating creates convection currents in the sluggish mantle rock that ultimately power the drift of tectonic plates at the surface, giving rise to mountain ranges and earthquakes.

But the intense ‘burning’ of radioactive fuel in nuclear reactors relies on a chain reaction in which nuclear decay of some atoms releases subatomic particles that stimulate the decay of others. This is possible only if the decaying atoms are much more concentrated than they generally are in rocks and minerals. “In the normal mantle, there is no way you could get a high enough concentration”, says van Westrenen.

Spontaneous ignition

Yet it is clear that natural nuclear reactors can occur. Crustal rocks at Oklo in Gabon, Africa, bear unambiguous evidence of spontaneous ignition of uranium fission in mineral deposits 1.7 billion years ago.

That is thought to be a very unusual case. But some researchers have previously suggested, although it’s not a widely held view, that gravity could cause a concentration of radioactive ultra-heavy elements such as uranium. These elements might sink down into Earth’s core, where they are enriched enough to ignite georeactors.

Such proposals don’t, however, seem to fit with what is known about how elements are distributed between the mantle and the core. De Meijer and van Westrenen now have a different idea, which draws on recent discoveries about the distribution of an isotope of the rare element neodymium in rocks2,3.

Those observations suggested that there is a ‘reservoir’ of material deep inside Earth, which formed soon after the birth of the planet, about 4.5 billion years ago, and has not mixed with the rest of the mantle.

The only place where such a reservoir could easily exist is at the very bottom of the mantle, at the boundary with the core, where convection currents don’t really reach to cause much stirring.

Live reactor

In a paper to be published in the South African Journal of Science1, the two researchers have estimated how much uranium the reservoir could contain. They note that uranium and its decay product plutonium are more readily incorporated into calcium silicate perovskite, a mineral which makes up 5% of the lower mantle, than into the two other minerals that make up this part of the deep earth. This concentrates the radioactive elements into a small volume.

All the same, the calculations show that an isolated, 4.5-billion-year-old reservoir at the core-mantle boundary would contain 20 times too low a concentration of these elements to ignite a chain reaction. That, however, is not a large deficit. De Meijer and van Westrenen say that melting and other geological processes could quite conceivably concentrate up the fissile material further until it crosses the ignition threshold.

In fact, they say, if there wasn’t this initial shortfall then the whole of the core-mantle boundary might conceivably have become a live nuclear reactor.


Bill McDonough, a geochemist at the University of Maryland in College Park, thinks that the idea of concentrating radioactive elements in a calcium perovskite reservoir at the base of the mantle is “eminently more credible” than previous proposals for how georeactors might form. “The authors have thought hard about this,” he says, but cautions that “the hypothesis requires that all conditions be just right for it to work”.

Such a reactor would probably function as a ’breeder’ reactor, generating plutonium fuel as it burns the original uranium. This means that such reactors could still be running today. What’s more, because the other decay products include helium and xenon, this could help to explain the confusing ratios of these elements in volcanic magma, van Westrenen suggests.

Proving the unseen

Balancing these ratios would require a nuclear reactor roughly 1,000 times more powerful than a typical man-made reactor, although van Westrenen points out that this power output is entirely possible, and would represent only a small proportion of the heat that escapes from Earth’s surface.

How can the existence of these reactors some 3,000 kilometres beneath our feet be proved? De Meijer and Westrenen say that the reactions will generate very light subatomic particles called antineutrinos, which can mostly pass right through Earth and so could be detected by instruments at the surface. Such particles produced by nuclear decay in the mantle have already been seen by a neutrino detector in Japan4.

Neutrino detectors that can sense the direction from which such particles came are now being planned. De Meijer and van Westrenen are both members of a Dutch collaboration called Stichting EARTH, which is aiming to develop such detectors for three-dimensional tomographic mapping of antineutrino sources in the earth. A georeactor would show up in such a survey as a particularly intense, localized source at the core-mantle boundary.

• References

1. de Meijer, R. J. & van Westrenen, W. S. Afr. J. Sci. (in the press).

2. Boyet, M. & Carlson, R. W. Science 309, 576–581 (2005).

3. Carlson, R. W., Boyet, M., Horan, M. Science 316, 1175–1178 (2007).

4. Araki, T. et al. Nature 436, 499–503 (2005).


Why is the earth’s core so hot? And how do scientists measure its temperature?

There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.

It takes a rather long time for heat to move out of the earth. This occurs through both "convective" transport of heat within the earth’s liquid outer core and solid mantle and slower "conductive" transport of heat through nonconvecting boundary layers, such as the earth’s plates at the surface. As a result, much of the planet’s primordial heat, from when the earth first accreted and developed its core, has been retained.

The amount of heat that can arise through simple accretionary processes, bringing small bodies together to form the proto-earth, is large: on the order of 10,000 kelvins (about 18,000 degrees Farhenheit). The crucial issue is how much of that energy was deposited into the growing earth and how much was reradiated into space. Indeed, the currently accepted idea for how the moon was formed involves the impact or accretion of a Mars-size object with or by the proto-earth. When two objects of this size collide, large amounts of heat are generated, of which quite a lot is retained. This single episode could have largely melted the outermost several thousand kilometers of the planet.

Additionally, descent of the dense iron-rich material that makes up the core of the planet to the center would produce heating on the order of 2,000 kelvins (about 3,000 degrees F). The magnitude of the third main source of heat—radioactive heating—is uncertain. The precise abundances of radioactive elements (primarily potassium, uranium and thorium) are poorly known in the deep earth.

In sum, there was no shortage of heat in the early earth, and the planet’s inability to cool off quickly results in the continued high temperatures of the Earth’s interior. In effect, not only do the earth’s plates act as a blanket on the interior, but not even convective heat transport in the solid mantle provides a particularly efficient mechanism for heat loss. The planet does lose some heat through the processes that drive plate tectonics, especially at mid-ocean ridges. For comparison, smaller bodies such as Mars and the Moon show little evidence for recent tectonic activity or volcanism.

We derive our primary estimate of the temperature of the deep earth from the melting behavior of iron at ultrahigh pressures. We know that the earth’s core depths from 2,886 kilometers to the center at 6,371 kilometers (1,794 to 3,960 miles), is predominantly iron, with some contaminants. How? The speed of sound through the core (as measured from the velocity at which seismic waves travel across it) and the density of the core are quite similar to those seen in of iron at high pressures and temperatures, as measured in the laboratory. Iron is the only element that closely matches the seismic properties of the earth’s core and is also sufficiently abundant present in sufficient abundance in the universe to make up the approximately 35 percent of the mass of the planet present in the core.

The earth’s core is divided into two separate regions: the liquid outer core and the solid inner core, with the transition between the two lying at a depth of 5,156 kilometers (3,204 miles). Therefore, If we can measure the melting temperature of iron at the extreme pressure of the boundary between the inner and outer cores, then this lab temperature should reasonably closely approximate the real temperature at this liquid-solid interface. Scientists in mineral physics laboratories use lasers and high-pressure devices called diamond-anvil cells to re-create these hellish pressures and temperatures as closely as possible.

Those experiments provide a stiff challenge, but our estimates for the melting temperature of iron at these conditions range from about 4,500 to 7,500 kelvins (about 7,600 to 13,000 degrees F). As the outer core is fluid and presumably convecting (and with an additional correction for the presence of impurities in the outer core), we can extrapolate this range of temperatures to a temperature at the base of Earth’s mantle (the top of the outer core) of roughly 3,500 to 5,500 kelvins (5,800 to 9,400 degrees F) at the base of the earth’s mantle.

The bottom line here is simply that a large part of the interior of the planet (the outer core) is composed of somewhat impure molten iron alloy. The melting temperature of iron under deep-earth conditions is high, thus providing prima facie evidence that the deep earth is quite hot.

Gregory Lyzenga is an associate professor of physics at Harvey Mudd College. He provided some additional details on estimating the temperature of the earth’s core:

How do we know the temperature? The answer is that we really don’t—at least not with great certainty or precision. The center of the earth lies 6,400 kilometers (4,000 miles) beneath our feet, but the deepest that it has ever been possible to drill to make direct measurements of temperature (or other physical quantities) is just about 10 kilometers (six miles).

Ironically, the core of the earth is by far less accessible more inaccessible to direct probing than would be the surface of Pluto. Not only do we not have the technology to "go to the core," but it is not at all clear how it will ever be possible to do so. As a result, scientists must infer the temperature in the earth’s deep interior indirectly. Observing the speed at which of passage of seismic waves pass through the earth allows geophysicists to determine the density and stiffness of rocks at depths inaccessible to direct examination. If it is possible to match up those properties with the properties of known substances at elevated temperatures and pressures, it is possible (in principle) to infer what the environmental conditions must be deep in the earth.

The problem with this is that the conditions are so extreme at the earth’s center that it is very difficult to perform any kind of laboratory experiment that faithfully simulates conditions in the earth’s core. Nevertheless, geophysicists are constantly trying these experiments and improving on them, so that their results can be extrapolated to the earth’s center, where the pressure is more than three million times atmospheric pressure. The bottom line of these efforts is that there is a rather wide range of current estimates of the earth’s core temperature. The "popular" estimates range from about 4,000 kelvins up to over 7,000 kelvins (about 7,000 to 12,000 degrees F). If we knew the melting temperature of iron very precisely at high pressure, we could pin down the temperature of the Earth’s core more precisely, because it is largely made up of molten iron. But until our experiments at high temperature and pressure become more precise, uncertainty in this fundamental property of our planet will persist.

Is it possible that the so-called "global warming" is due to heat diffusing from the earth’s interior to its surface, as the earth continues to cool?

We all know that the interior of the earth is composed of exceedingly hot molten iron, and that the tendency of heat is to diffuse from hot to cold. Humans cannot control the cooling of the earth, and this cooling process has to involve diffusion of heat from the interior to the much cooler surface/mantle. The movement of the tectonic plates against each other during earthquakes (large or small) must have an effect on such heat diffusion from core to surface.

Earth’s interior is actually only 0.03% of Earth’s total energy

The flow of heat from Earth’s interior to the surface is estimated at 47 terawatts (TW) and comes from two main sources in roughly equal amounts: the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of the Earth

Earth’s internal heat powers most geological processes and drives plate tectonics Despite its geological significance, this heat energy coming from Earth’s interior is actually only 0.03% of Earth’s total energy budget at the surface, which is dominated by 173,000 TW of incoming solar radiation The insolation that eventually, after reflection, reaches the surface penetrates only several tens of centimeters on the daily cycle and only several tens of meters on the annual cycle. This renders solar radiation irrelevant for internal processes.


Taking earth’s inner temperature: Surprising new study finds that the mantle is hotter than we thought

The temperature of Earth’s interior affects everything from the movement of tectonic plates to the formation of the planet.

A new study led by Woods Hole Oceanographic Institution (WHOI) suggests the mantle—the mostly solid, rocky part of Earth’s interior that lies between its super-heated core and its outer crustal layer—may be hotter than previously believed. The new finding, published March 3 in the journal Science, could change how scientists think about many issues in Earth science including how ocean basins form. "At mid-ocean ridges, the tectonic plates that form the seafloor gradually spread apart," said the study’s lead author Emily Sarafian, a graduate student in the MIT-WHOI Joint Program. "Rock from the upper mantle slowly rises to fill the void between the plates, melting as the pressure decreases, then cooling and re-solidifying to form new crust along the ocean bottom. We wanted to be able to model this process, so we needed to know the temperature at which rising mantle rock starts to melt." But determining that temperature isn’t easy. Since it’s not possible to measure the mantle’s temperature directly, geologists have to estimate it through laboratory experiments that simulate the high pressures and temperatures inside the Earth. Water is a critical component of the equation: the more water (or hydrogen) in rock, the lower the temperature at which it will melt. The peridotite rock that makes up the upper mantle is known to contain a small amount of water. "But we don’t know specifically how the addition of water changes this melting point," said Sarafian’s advisor, WHOI geochemist Glenn Gaetani. "So there’s still a lot of uncertainty." To figure out how the water content of mantle rock affects its melting point, Sarafian conducted a series of lab experiments using a piston-cylinder apparatus , a machine that uses electrical current, heavy metal plates, and stacks of pistons in order to magnify force to recreate the high temperatures and pressures found deep inside the Earth. Following standard experimental methodology, Sarafian created a synthetic mantle sample. She used a known, standardized mineral composition and dried it out in an oven to remove as much water as possible. Until now, in experiments like these, scientists studying the composition of rocks have had to assume their starting material was completely dry, because the mineral grains they’re working with are too small to analyze for water. After running their experiments, they correct their experimentally determined melting point to account for the amount of water known to be in the mantle rock. "The problem is, the starting materials are powders, and they adsorb atmospheric water," Sarafian said. "So, whether you added water or not, there’s water in your experiment." Sarafian took a different approach. She modified her starting sample by adding spheres of a mineral called olivine, which occurs naturally in the mantle. The spheres were still tiny—about 300 micrometers in diameter, or the size of fine sand grains—but they were large enough for Sarafian to analyze their water content using secondary ion mass spectrometry (SIMS). From there, she was able to calculate the water content of her entire starting sample. To her surprise, she found it contained approximately the same amount of water known to be in the mantle. Based on her results, Sarafian concluded that mantle melting had to be starting at a shallower depth under the seafloor than previously expected.

To verify her results, Sarafian turned magnetotellurics—a technique that analyzes the electrical conductivity of the crust and mantle under the seafloor. Molten rock conducts electricity much more than solid rock, and using magnetotelluric data, geophysicists can produce an image showing where melting is occurring in the mantle. But a magnetotelluric analysis published in Nature in 2013 by researchers at the Scripps Institution of Oceanography in San Diego showed that mantle rock was melting at a deeper depth under the sea floor than Sarafian’s experimental data had suggested. At first, Sarafian’s experimental results and the magnetotelluric observations seemed to conflict, but she knew both had to be correct. Reconciling the temperatures and pressures Sarafian measured in her experiments with the melting depth from the Scripps study led her to a startling conclusion: The oceanic upper mantle must be 60°C ( 110°F) hotter than current estimates," Sarafian said. A 60-degree increase may not sound like a lot compared to a molten mantle temperature of more than 1,400°C. But Sarafian and Gaetani say the result is significant. For example, a hotter mantle would be more fluid, helping to explain the movement of rigid tectonic plates.


Greenland ice sheet IS melting but much of the heating is coming from INSIDE the earth

Ice in Greenland is melting partly because of heat from the Earth’s mantle, according to a team of international researchers.

The group claims that they are the first to find a connection between melting of the Greenland ice sheet and the high heat flow from the Earth’s mantle.

The findings, they suggest, could have implications for future predictions on climate change and the reasons behind ice melt in the region.

The Greenland ice sheet is often considered an important contributor to future global sea-level rise over the next century or longer.

In total, it contains an amount of ice that would lead to a rise of global sea level by more than seven metres, if completely melted.

The ice loss from the ice sheet has been increasing over the last decade, with half of it attributed to changes in surface conditions with the remainder due to increased iceberg calving - the process by which ice detaches from the glacier to become an iceberg.

The international research initiative IceGeoHeat, led by the GFZ German Research Centre for Geosciences, said that the effect of the Earth’s crust and upper mantle in current climate modelling are too simplistic.

They modelled the Earth’s mantle against the ice sheet and found that melting occurs in a given area due to the composition of the mantle underneath it.

Writing in the current online issue of Nature Geoscience, the group argues that this effect cannot be neglected when putting together data on climate change.

The Greenland ice sheet loses about 227 gigatonnes of ice per year and contributes about 0.7 millimeters to the currently observed mean sea level change of about 3 mm per year. The team point out, however, that existing model calculations were based on a consideration of the ice cap.

GFZ scientists Alexey Petrunin and Irina Rogozhina have now combined earlier ice and climate models with their new thermo-mechanical model for the Greenland lithosphere.

‘We have run the model over a simulated period of three million years, and taken into account measurements from ice cores and independent magnetic and seismic data’, said Petrunin. ‘The temperature at the base of the ice, and therefore the current dynamics of the Greenland ice sheet is the result of the interaction between the heat flow from the earth’s interior and the temperature changes associated with glacial cycles,’ said Irina Rogozhina who initiated IceGeoHeat.

‘We found areas where the ice melts at the base next to other areas where the base is extremely cold.’

The current climate is influenced by processes that go far back into the history of Earth: the Greenland lithosphere is 2.8 to 1.7 billion years old and is only about 70 to 80 km thick under Central Greenland.

The researchers believe that the coupling of models of ice dynamics with thermo-mechanical models of the solid earth allows a more accurate view of the processes that are melting the Greenland ice.


Earth’s core far hotter than thought

New measurements suggest the Earth’s inner core is far hotter than prior experiments suggested, putting it at 6,000C - as hot as the Sun’s surface.

The solid iron core is actually crystalline, surrounded by liquid.

But the temperature at which that crystal can form had been a subject of long-running debate.

Experiments outlined in Science used X-rays to probe tiny samples of iron at extraordinary pressures to examine how the iron crystals form and melt.

Seismic waves captured after earthquakes around the globe can give a great deal of information as to the thickness and density of layers in the Earth, but they give no indication of temperature.

That has to be worked out either in computer models that simulate the Earth’s insides, or in the laboratory.

X-ray vision

Measurements in the early 1990s of iron’s "melting curves" - from which the core’s temperature can be deduced - suggested a core temperature of about 5,000C.

"It was just the beginning of these kinds of measurements so they made a first estimate... to constrain the temperature inside the Earth," said Agnes Dewaele of the French research agency CEA and a co-author of the new research.

"Other people made other measurements and calculations with computers and nothing was in agreement. It was not good for our field that we didn’t agree with each other," she told BBC News.

The core temperature is crucial to a number of disciplines that study regions of our planet’s interior that will never be accessed directly - guiding our understanding of everything from earthquakes to the Earth’s magnetic field.

"We have to give answers to geophysicists, seismologists, geodynamicists - they need some data to feed their computer models," Dr Dewaele said.

The team has now revisited those 20-year-old measurements, making use of the European Synchrotron Radiation Facility - one of the world’s most intense sources of X-rays.

To replicate the enormous pressures at the core boundary - more than a million times the pressure at sea level - they used a device called a diamond anvil cell - essentially a tiny sample held between the points of two precision-machined synthetic diamonds.

Once the team’s iron samples were subjected to the high pressures and high temperatures using a laser, the scientists used X-ray beams to carry out "diffraction" - bouncing X-rays off the nuclei of the iron atoms and watching how the pattern changed as the iron changed from solid to liquid.

Those diffraction patterns give more insight into partially molten states of iron, which the team believes were what the researchers were measuring in the first experiments.

They suggest a core temperature of about 6,000C, give or take 500C - roughly that of the Sun’s surface.

But importantly, Dr Dewaele said, "now everything agrees".


Earth’s Core 1,000 Degrees Hotter Than Expected

Earth’s internal engine is running about 1,000 degrees Celsius (about 1,800 degrees Fahrenheit) hotter than previously measured, providing a better explanation for how the planet generates a magnetic field, a new study has found. A team of scientists has measured the melting point of iron at high precision in a laboratory, and then drew from that result to calculate the temperature at the boundary of Earth’s inner and outer core — now estimated at 6,000 C (about 10,800 F). That’s as hot as the surface of the sun. The difference in temperature matters, because this explains how the Earth generates its magnetic field. The Earth has a solid inner core surrounded by a liquid outer core, which, in turn, has the solid, but flowing, mantle above it. There needs to be a 2,700-degree F (1,500 C) difference between the inner core and the mantle to spur "thermal movements" that — along with Earth’s spin — create the magnetic field. The previously measured core temperature didn’t demonstrate enough of a differential, puzzling researchers for two decades. The new results are detailed in the April 26 issue of the journal Science.

The centerpiece of the experiment was a new X-ray technique that takes measurements faster than before. Iron samples compressed in the laboratory typically last for only a few seconds, making it difficult to determine in previous experiments if the iron is still a solid, or if it is starting to melt. The technique makes use of diffraction that occurs when X-rays, or other forms of light, hit an obstacle and bend around it. Scientists sent X-ray bursts at the sample and observed the "signature" of heating, which is a diffuse ring, that pinpointed the temperature. These experiments pegged the melting point of iron at 4,800 C (about 8,700 F) at a pressure of 2.2 million times that is found on Earth’s surface at sea level. Extrapolating from that measurement, scientists estimated the boundary between Earth’s inner and outer core is a searing 10,832 F, give or take about 930 degrees, at a pressure of 3.3 million atmospheres (or 3.3 million times the atmospheric pressure at sea level). Participating organizations in the experiment include CEA (a French national technological research organization), the French National Center for Scientific Research (CNRS) and the European Synchrotron Radiation Facility (ESRF).


A thousand more degrees for the center of the Earth !!!

The kernel boundary is at a higher temperature than the solar surface and yet some people can not imagine that the kernel is responsible for the warming of the Earth while it is clear that the Earth’s mantle has also greatly increased temperature !!!

We have discovered a terrestrial warming which absolutely can not come from that of the atmosphere: it is the warming of the "mantle" of the Earth !!!

Not a little warming: 60 ° !!!

Read here in french language

Do not heat up 60 ° of the solid mass by heating one or two degrees above the air!

It is the core of the Earth that warms the whole thing well.

The Earth’s core is mounted at 6000 ° at the surface of the nucleus:

Read here in french a study of scientists from the Grenoble European synchrotron (ESRF), the CEA and the CNRS

It is the hot core of the Earth, not global warming, that is responsible for melting the Greenland Ice Cap.

The icecap of Greenland melts, but it turns out that the responsible is not global warming, as some would have you believe. Instead, researchers have now found evidence that a heat source hidden at the bottom of the planet is behind this melting ice that carries glaciers into the ocean.

Researchers from the University of Aarhus in Denmark used a ten-year study of Young Sound Fjord in Greenland to draw their conclusions. Throughout the survey, measurements were made on salinity levels and temperatures in the fjord, where water at depths ranging from 200 to 330 m gradually warmed.

They discovered that much of this heat came from inside the Earth. According to their estimates, 100 megawatts of energy per square meter has been transferred from the interior of the Earth to the fjord, and it is believed that similar amounts of heat have been transferred to the bottom of the surrounding glaciers. That’s roughly equivalent to a 2-megawatt wind turbine that sends electricity to a huge radiator at the bottom of the fjord all year long. Their findings were published in Scientific Reports.

The heat loss of the interior of our planet warms the temperatures of deep water where the fjords are, melting the glaciers. The heat, which is called geothermal heat flux, is found everywhere on our planet and goes back to its birth. Since flows are not evenly distributed, they can be difficult to measure. This study is unique in that it has been successful in identifying the heat flux of warming an almost stagnant water mass that has lasted for ten years.

In addition, scientists say that warming and melting under the icecaps that these heat flows induce "essentially lubricate the interface between ice and soil, which greatly accelerates the movement of ice."

Referring to the Greenland icecap as a GIS, the researchers write in the abstract: "A compilation of Greenland heat flux records shows the existence of geothermal heat sources under GIS and could explain the high zones of glacier speed as the glacial current of northeastern Greenland. The temperatures at the heart of our planet are estimated at around 6,000 degrees Celsius. The sun’s surface has similar temperatures, and this type of heat can be seen when volcanoes erupt or in hot springs, for example.

This study shows very clearly that nature itself is responsible for the melting of ice sheets in Greenland.

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