Dr. Roger Pielke Sr. writes:
News Article On The Earth’s Heat From Radioactive Decay
An intriguing news article has appeared by Charles Q. Choi titled
Radioactive decay fuels Earth’s inner fires
The article includes the text
“Extraordinary amount of heat remains from primordial days, scientists say
The researchers found the decay of radioactive isotopes uranium-238 and thorium-232 together contributed 20 trillion watts to the amount of heat Earth radiates into space, about six times as much power as the United States consumes. U.S. power consumption in 2005 averaged about 3.34 trillion watts.
As huge as this value is, it only represents about half of the total heat leaving the planet. The researchers suggest the remainder of the heat comes from the cooling of the Earth since its birth.”
To convert the estimate in the MSNBC news article to watts per meter squared, 20 trillion watts must be divided by the area of the Earth [5.1 x 10^14 meter squared] which yields a heat source of 0.039 watts per meter squared.
This is well less than the significant radiative forcings as estimated in figure SPM.2 in the 2007 IPCC WG1 report and, except for local effects where lava flows and volcanic eruptions are occuring , this heat is of minor climatic importance [the outgassing of sulphur dioxide and other chemicals and of ash, of course, are a different issue]. The heating of the interior and resulting effect on currents in the Earth’s mantle, however, are important in climate on very long time scales as this helps drive plate tectonics, such as continental drift.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
10 TerraWatts or 0.03 W/M^2.
Makes me wonder how much that value was 4 billion years ago.
A brighter burning early Sun gave way to a much lower output Sun of today.
The mass and density of the oceans does form a time barrier to outright radiation, much like the density and mass of the Sun keeps nuclear output from reaching the surface for 1 million years.
So, in order for CO2 and greenhouse gases to significantly slow the cooling off of the Earth, the total density AND mass of the atmosphere has to increase significantly. All it would take to upset this balance is for the Sun to drop its output…which it has done over billions of years. But, in reality, the Earth is not in inertial thermal balance, but leaks slowly and irrevocably over great expanses of time.
The ultimate path of planetary cooling is moderated by the great mass of the Sun (which moderates the Solar Fusion output) but still ends up looking like a frayed rope. Both are seeking a lower energy state, and the final outcome is cold, dead bodies floating in space.
Relax, it’s going to take billions of years.
Life on Earth has existed for 80% of the Earths history. Nothing we can do will heat it up beyond that total range of temperature, though we could launch enough Nukes to waste all life except the most basic.
????this heat is of minor climatic importance???
REPEAT> Yeah!!! Only,If you ignore the 3 million +++ SUBMARINE Volcanic and black smokers that warm the Ocean AND THERE HAS BEEN A 400% INCREASE IN ACTIVITY TO BOOT.
This IS where and why there is the current rise of C02 just like before every deep ice age.
The proof is in the timing of the now due 65million year cycle,in fact WE ARE ENTERING A multiple cycle called a Converging Harmonic Cycle.
We are in the same spiral arm and crossing the thin magnetic disc around the Galactic Equator,and people don’t seem to have worked out yet it seems, why the Co2 is rising is RIGHT ON TIME for the 65million year cycle to be ALL natural.Well 97%? maybe.
TAIWAN increased seismicity
http://sites.google.com/site/jacquesangelier/InstrumentalEarthquakes.jpg
http://www.earth.webecs.co.uk/
Figure 2.7 Seismic data acquired on the Norwegian continental shelf in the period 1962 – 2000
http://www.npd.no/engelsk/npetrres/petres2001/images/figurer/2-7.gif
Take a look at these USGS earthquake numbers. Go here for more details. You have to wonder how anyone could justify that earthquakes aren’t increasing. Their strengths certainly are.
http://standeyo.com/NEWS/08_Earth_Changes/080510.diz.bogus.story.html
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
http://www.poetpatriot.com/timeline/tmlndisvolcanos.htm
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Why doesn’t the deep ocean freeze up? My understanding was that the enormous amounts of pressure applied to non-compressable water keeps that water from freezing.
These are geologists, and they’re talking about heat leaving the molten part of the planet. What is happening on the surface is irrelevant, other than how it messes up their rock samples. Don’t compare these numbers to the total surface/atmospheric radiation budget, as they’re clearly only dealing with the geologic heat component.
The current numbers on part of Wikipedia are “Mean heat flow is 65 mW/m2 over continental crust and 101 mW/m2 over oceanic crust.[12]”. http://en.wikipedia.org/wiki/Geothermal_gradient
@ur momisugly richard verney @ur momisugly Roy Spencer @ur momisugly Dave Springer @ur momisugly John F. Hultquist
Think about this:
When the Earth was warm in paleoclimatological past – Plate tectonic activity was high.
When the Earth was cool in paleoclimatological past – Plate tectonic activity is low. And that is today where Milankovitch cycles play a very large role in our climate causing the huge Pleistocene temperature oscillations which were not there 40 million years ago or more. I am speaking here of Long-Term climate change. Not the short term one. There were/are always shortterm fluctuations in climate. Even 50 million years ago.
Where are most of these oceanic ridges and subduction zones situated which cause increased or decreased tectonic activity? Yes underwater in the Deep Ocean.
Is Deep Ocean Temperature solely controlled by Atmospheric Temperature? Or could Geothermal Heat Exchange with Deep Oceanic water be a serious factor to consider?
Science underestimates the influence of Geothermal Heat Exchange with the Deep Ocean.
A warmer Deep Ocean means a warmer climate. http://www.essc.psu.edu/essc_web/seminars/spring2006/jan18/Zachosetal.pdf (Fig. 2)
-This hypothesis could easily explain the existence of liquid water during the Faint Young Sun Paradox. How warm (geothermally) was Young Earth anyway?
-It could easily explain why Snowball Earth melted. (Decreased tectonic activity causing the Earth to freeze over – Increased tectonic activity causing ocean temperature to rise and melt the ice)
-It could also easily explain why Hyperthermals recover so beautifully. (This is somewhat more complicated to explain in a few sentences)
Three problems science is struggling on for years, even decades.
http://www.youtube.com/watch?v=PZjPGdXMMso Watch the difference in speed of the plates and heat exchange with the air in this case. Earth tectonic plates move almost identical. The physics is practically the same. One can even witness flood basalt events at 0:05, 0:12, 0:18, 0:22, 0:25.
The difference here is: Timescale.
We know so little about the geological history of the Earth.
This hypothesis could be a beautiful contender for replacing the CO2 theory.
So, essentially, the US energy consumption is fart all in space and hell for warming the earth’s climate as well.
That’s good to know, since it means that Australia’s energy consumption is not even a whiff of a sneaker fart in space and hell for warming the earth’s climate.
I strongly suspect that the atmospheric lapse rate would pretty much govern the temperature of the ocean floor if the water were “magically” removed without changing the albedo of the earth as a whole. Since the lapse rate is ~ 6.5 C/km and people here are using ~ 4.5 km as the depth, the temperature would be ~ 30 C warmer than at current sea level.
The fact that the sea floor is closer to the core would be only a minor effect, I strongly suspect — much the same way that a valley is warmer than a mountain top because of the lapse rate, not because of the distance from the center. Or conversely, the temperature 1 mile below Denver (ie at sea level) will be much hotter than in Los Angeles, even though both are the same distance from the center. The geographical gradient must almost certainly be steeper under the ocean than under the land. (in fact, this scenario would decrease the difference, since we would be warming the ocean floor considerably.)
richard verney says: July 21, 2011 at 10:48 am
But this is a false analogy. If you took that pit and sloped the sides out to make it a typical valley or ocean basin 20+ km across, the bottom of the valley would still be warm, but at an atmospheric gradient of ~ 6.5 C/km, not the geological gradient of ~ 25 C/km (assuming the number quoted above it correct).
Barry Day says: July 21, 2011 at 10:34 am
If you check the numbers, the area of the ocean is about 300 million km^2. so there is one smoker for every 10 km^2 = 10 million m^2. Even if the smokers average a megawatt of heat, then that is still only 0.1 W/m^2. Compared to 240 W/m^2 from the sun, this 0.1 W/m^2 of thermal energy is indeed “minor”.
P.S. This agrees remarkably well with wikipedia “Heat flows constantly from its sources within the Earth to the surface. Total heat loss from the earth is 44.2 TW (4.42 × 1013 watts).[12] Mean heat flow is 65 mW/m2 over continental crust and 101 mW/m2 over oceanic crust.[12] ”
http://en.wikipedia.org/wiki/Geothermal_gradient
When you think that one of the best insulator, a vacuum insulated panel, has a R value of at best 8.8 K m^2/W, using the 0.039 W/m^2 value and that of the emperature of the upper mantle, we get a R-Value for the crust of about 24,950 K m^2/W.
Interesting article, thanks. Also interesting to compare the Earth’s heat with the net heat rate radiated by a human body. It’s on the order of 100 watts per square meter (according to
http://en.wikipedia.org/wiki/Black_body#Human_body_emission)
So, only about a half a trillion watts total.
😐
The issue of intense heat sources within the Earth’s core was not understood in the 19th century. Thus, Lord Kelvin dismissed Darwin’s theories by showing, using calculations of heat radiation from the earth, that not enough time had been available for evolution by natural selection. Darwin was appalled, and he had no conclusive answer, though he knew he was right.
visit: http://iamyouasheisme.wordpress.com/2010/01/12/quantitative-deep-freeze/
Barry Day says:
July 21, 2011 at 10:34 am
Figure 2.7 Seismic data acquired on the Norwegian continental shelf in the period 1962 – 2000
Unfortunately your Norwegian seismic data consists of a measure of the number of kilometers seismic survey vessels have travelled collecting seismic data for oil exploration – nothing to do with earthquakes.
NPD stands for Norwegian Petroleum Directorate – http://www.npd.no
Title: 20 trillion watts is not even Trenberth’s missing heat
20 trillion watts isn’t even close to the rating of the speakers in the car the kid down the street drives around. ;o)
Seriously, I was wondering what is the possible error for that number; 2X? 3X? 10X? +/- 2 trillion?
http://www.scientificamerican.com/blog/post.cfm?id=nuclear-fission-confirmed-as-source-2011-07-18
Misquoted and misreported by Scientific American.
@ur momisugly richard verney.
You are ignoring the atmosphere and the oceans, both of which are great at heat transfer. Dig two pits 8 km deep, one at the equator and one at the south pole. Are they both the same temperature (and very hot) at the bottom? No. Neither will reach your 126o temp either.
The mine analogy also doesn’t work. Go underground 2 km and the temperature is not 50-60o but more like 35o. This is because they pump down cool air. Take away the atmosphere and the oceans and eliminate convection and then yes, your point could be reconsidered.
G. Karst – I did not calculate the heating rate; I just converted their analyzed heat flux to a per meter squared unit. The Earth’s crust, of course, results in a buffering between the surface and the higher heat in the interior.
ferd berple says:
July 21, 2011 at 9:24 am
“…Water likely extends downwards under the oceans until it is turned to super critical steam at immense pressure, which will then vent upwards carrying heat back towards the ocean floor…”
Close, but not steam… and not really water either. At a hydrostatic depth of about 2.25 km, water is above it’s supercritical point of 22.064 MPa (3200 PSIA). 2.25 km is about 22.1 MPa. It won’t matter how much you heat it, it won’t go into a gas state.
In rock, at this depth and pressure, it tends to do other interesting things… like lowering the melting point of the rock that it’s entrained in… or joining the chemical structure such as in amphiboles and other hydrous reactions.
From Global Tectonics 3rd ed (Kearey, Klepeis and Vine):
The penetration of this convection is not known, but it is possible that it is crust-wide. It is thought that hydrothermal circulation of seawater in the crust beneath ocean ridges transports about 25% of the global heat loss, and is clearly a major factor in the Earth’s thermal budget.
Baa Humbug says:
July 21, 2011 at 11:25 am
“Why doesn’t the deep ocean freeze up?”
For the same reason as the water in a lake, pond, or reservoir of sufficient depth (for its location). Water at a certain temperature (~3.98 C) reaches maximum density and sinks. Beyond that temperature, that is, as the water continues to lose heat, the water becomes (again) less dense and more buoyant and will eventually freeze at the surface. It does so at the water-atmosphere boundary because the air (above) is colder then the water and the heat flow is from warmer to colder.
As the comments indicate, the ocean floor temperature will be above that of the adjacent water temperature and again heat will flow from the rock (warm) to the water (cold). There is no reason for the water to freeze at sufficient depth.
Water is the strangest substance the average person ever encounters. The list of its oddities is long –density with temperature can be found here:
http://en.wikipedia.org/wiki/Water_(properties)#Density_of_water_and_ice
I think the heat in the Earth comes more from the gravitational dough-hooking the Moon and Sun provide than anything to do with radioactive decay. The lack of general understanding of physics most scientists expose is quite astounding.
Sorry, add me to the Oops list.
http://www.micom.net/oops/
In my last comment I left out the degree sign on the temperature. It should be ~3.98° C.
I have to use ASCII Code to get the symbol. For ‘degree’ it is Alt 0176.
http://www.ascii-code.com/
enjoying the discussion of earth’s heat which has always seemed, to me, counterintuitively ignored in the climate world. i’m always struck when i hear that “absorbed solar radiation is 10,000 times as great as the heat emitted into the atmosphere via the earth’s thermal gradient”, and therefore the earth’s heat content of 10 to 31st power of joules can be completely ignored.
sounds like AGW propagandists cherry-picking sound bites.
it seems that it would be equally fair to say that, at night, the heat emitted to the atmosphere by the earth’s crust is MILLIONS (or, billions for that matter) of times greater than any heat received from the sun – since, at night, there is NO heat received from the sun.
at night, when there is no incoming solar energy, the stored and emitted heat coming from the earth is the only heat entering the atmosphere for 1/2 the globe. the heck with 240 watts per square meter at night – it doesn’t happen.
accepting that the convention for earth’s geothermal gradient heat is expressed in watts per meter squared terms, it seems to me that consideration needs to be given to the fact that the earth’s crust (dirt, sand, water, rock, etc) is FAR more dense than the air above it – on the order of 800-2000 times as dense – ranging from the density of water to, say, granite.
therefore, assuming an adjacent cubic foot of air and cubic foot of crust would tend to be the same temperature at any place on earth, the fact is that the cubic foot of earth under the air would contain 800 to 2000 TIMES the amount of heat. in other words, 1 square foot of earth’s crust, 1 foot deep, must hold more heat than a mile of air above it. why this isn’t significant is beyond me, especially considering that the earth is constantly being heated from underneath, whereas the air is only being heated by the sun when the sun shines – and the sun’s rays wax and wane all day long fading to zero at nighttime.
the trapped chilean coal miners were hot because of that thermal gradient, not from any effect of the sun at all.
and so, it seems to me anyway, that the heat content of the earth must be the dog that wags the climate’s tail rather the heat content of our thin layer of atmosphere being the tail that wags the dog.
Come to think of it: the input power is equal to that of the the converted energy output plus waste energy output. Both the converted energy output and the waste energy output is less than the inputed power but is equal to the the inputed power.
Since a part of the inputed power is converted to good and proper use, like apples and oranges, the output energy of the US power consumption is then, of course, less than the stated power consumption and the energy to heat conversion of that power consumption is really just bugger all in that great scheme of things.
So why would anyone be as derange a communist as to tax, by the hundreds of billions, the US power consumption if it is less ‘an a sneaker of a whiff of a farts problem in space and hell?
John F. Hultquist says:
July 21, 2011 at 2:39 pm
Sorry, add me to the Oops list.
http://www.micom.net/oops/
“In my last comment I left out the degree sign on the temperature. It should be ~3.98° C.
I have to use ASCII Code to get the symbol. For ‘degree’ it is Alt 0176.
http://www.ascii-code.com/”
° Thanks, John. I just had to try it.° This is a very interesting discussion but I am not sure whom to believe! I do know SSam is correct re water at high pressure.
prjindigo says: J uly 21, 2011 at 2:29 pm
An interesting hypothesis. Please provide calculations of the magnitude of this heating effect. Or a link to textbooks or scientific articles that quantify the tidal heating of the earth. Enlighten us on the proper physics.
Or enlighten us as to the mistakes in the article attributing half the heating to radioactive decay as evidenced by detection of neutrinos.
Lichanos-Kelvin actually had a contemporary critic, and although I have often read it said (and repeated myself) that Kelvin’s error was no fault of his own, as he couldn’t have known about radioactive decay. Except that Kelvin made another error, namely he modeled the mantle as rigid, not fluid, and thus no convection within it. His critic was John Perry, and as early as 1895 he got an estimate in the right order of magnitude, just from accounting for that:
http://www.geosociety.org/gsatoday/archive/17/1/pdf/i1052-5173-17-1-4.pdf