Forgot your password?
typodupeerror
Earth Space News Science

Is the Earth Gaining Or Losing Mass? 356

Posted by timothy
from the do-your-genes-make-this-planet-look-fat? dept.
Hugh Pickens writes writes "BBC recently asked physicist and Cambridge University professor Dave Ansell to draw up a balance sheet of the mass that's coming in to the earth, and the mass going out to find out if the earth is gaining or losing mass. By far the biggest contributor to the world's mass is the 40,000 tonnes of dust that is falling from space to Earth every year. 'The Earth is acting like a giant vacuum cleaner powered by gravity in space, pulling in particles of dust,' says Dr. Chris Smith. Another factor increasing the earth's mass is global warming which adds about 160 tonnes a year because as the temperature of the Earth goes up, energy is added to the system, so the mass must go up. On the minus side, at the very center of the Earth, within the inner core, there exists a sphere of uranium five mile in diameter which acts as a natural nuclear reactor so these nuclear reactions cause a loss of mass of about 16 tonnes per year." (Read more, below.)
Pickens continues: "What about launching rockets and satellites into space, like Phobos-Grunt? Smith discounts this as the mass is negligible and most of it will fall back down to Earth again anyway. But by far the biggest factor in earth's weight loss are the 95,000 tonnes of hydrogen that escape from the atmosphere every year. 'The other very light gas this is happening to is helium and there is much less of that around, so it's about 1,600 tonnes a year of helium that we lose.' Taking all the factors into account, Smith reckons the Earth is getting about 50,000 tonnes lighter a year, which is just less than half the gross weight of the Costa Concordia, the Italian cruise liner that recently ran aground."
This discussion has been archived. No new comments can be posted.

Is the Earth Gaining Or Losing Mass?

Comments Filter:
  • by Anonymous Coward on Thursday February 02, 2012 @04:11PM (#38906835)

    No such thing. And warming the earth doesn't make it more massive.

  • by tiffany352 (2485630) on Thursday February 02, 2012 @04:13PM (#38906865)
    According to E=mc^2, one gram of matter is equivalent to 10^13 J of energy (according to Wolfram|Alpha).
  • by Trepidity (597) <delirium-slashdot@@@hackish...org> on Thursday February 02, 2012 @04:17PM (#38906941)

    Some models do have some kind of nuclear-reactor thing going on at the very center, but it's indeed not right to present it as some kind of fact, when it's greatly disputed what might be there (and our evidence is very circumstantial). As far as I can trace it, the proposal for a "nuclear georeactor" in a sub-core of the inner core is due to J.M. Herndon, who proposed it in 1996 [pnas.org], and has since developed the idea in various other papers. I don't think it's anywhere near consensus, though.

  • by noh8rz2 (2538714) on Thursday February 02, 2012 @04:17PM (#38906945)

    So now burning (hint, just a chemical action) some dead dinosaur is releasing the energy equivilent of 160 TONNES?

    I'm pretty sure he means that if the surface temperature increases by 1 degree C, then that corresponds to a higher amount of energy in the planet. it has nothing to do with burning fuel or anything else.

  • by Oswald McWeany (2428506) on Thursday February 02, 2012 @04:21PM (#38907021)

    Depends which globe you are talking about. If you're not talking about Earth- you're off topic.

    If you're talking about Earth and look at overall trend analysis graphs covering the last 100 years- the last 15 years fit in the scale correctly. Also 9 of the 10 warmest years on record have occurred during the past 15 years.

  • by blueg3 (192743) on Thursday February 02, 2012 @04:28PM (#38907123)

    So now burning (hint, just a chemical action) some dead dinosaur is releasing the energy equivilent of 160 TONNES? Eh?

    No. Burning is mass-neutral. Not only is it chemical, as you point out, but the energy released during burning is still in Earth, so by mass-energy-conservation, the total mass of the Earth is unchanged.

    It's the increasing average temperature of the Earth that causes the increase in mass. That temperature increase is not energy released from burning fuel, but rather additional energy captured from solar radiation (as a result of increased atmospheric CO2). So ultimately all the additional mass is coming from solar radiation.

    160 tons of mass ~= 10^22 J
    Solar irradiance over the surface of the Earth ~= 10^17 W ~= 10^24 J/yr

    Math people, try it sometime.

    I see that you didn't take your own advice. I see no math in your post whatsoever, despite the fact that 1 kg of mass in energy is easy to compute and the total energy used by civilization has been estimated before.

    IF one assumes AGW the mass of heating the crust and atmosphere of the earth a tiny fraction of a degree per year isn't going to give tons either.

    See, here math would have been useful.

  • by necro81 (917438) on Thursday February 02, 2012 @04:33PM (#38907215) Journal
    I think the point the author is making isn't about the energy of burning fossil fuels, it's about the heat trapping that results. Normally the Earth is at ~100% energy balance with respect to solar radiation: a lot comes in (174 petawatts), and just about all of it gets radiated back out, continuously. But by trapping extra energy here on Earth in the form of heat, AGW gradually increases the Earth's total energy. E=mc^2 is not just for nuclear reactions: any system that gains or loses energy effectively gains or loses an equivalent mass. By how much? This guy says it's the energy equivalent of 160 tons of mass 160 tons, when converted to energy, is 1.44*10^22 Joules: a whole bigass boatload of energy. But, it is actually rather small (1/400th) compared to the total energy received by Earth from the sun in one year. So it doesn't take but a tiny percentage change the energy balance, accumulated over many decades, to get 160 tons of mass.
  • by blueg3 (192743) on Thursday February 02, 2012 @04:48PM (#38907479)

    This estimate would be vaguely correct if you used the Earth's surface area. However, the Earth's cross-sectional area is area of the 2D disc that is formed by a meridian. The area of solar radiation it absorbs is exactly its cross-sectional area. (What part of the surface that happens to be changes as time passes and a unit of sunlight is spread over a larger surface around the edges, but the total area is constant and is simply the cross-sectional area.)

  • by iggymanz (596061) on Thursday February 02, 2012 @04:49PM (#38907485)

    the mainstream view is that the iron-nickel core of the earth is of the same source and composition of iron-nickel asteroids, which have little or no uranium.

  • by NikeHerc (694644) on Thursday February 02, 2012 @04:55PM (#38907571)
    I have no idea what you are talking about. Are you responding to someone, or just ranting into the ether?

    Dude, I got his blaster comment. Best laugh I've had all day!
  • by Diamonddavej (851495) on Thursday February 02, 2012 @05:07PM (#38907741)

    There's no evidence of a georeactor in the Earth's core. We know this by measuring the abundance of geoneutrinos - neutrinos generated by radioactive decay and nuclear fission. The KamLAND, Japan and Borexino, Italy discovered a ~50% deficit in geoneutrinos i.e. 22 of 44 TerraWatts of heat comes from radioactive decay. The rest is primordial, left over from the Earth's cataclysmic formation. If there was a georeactor there would have been an anomalous abundance in geoneutrinos (KamLAND detected fission neutrinos from nearby Japanese nuclear reactors).

    The hypothesis of a georeactor, powered by a 16km diameter sphere of Uranium, was put forward by maverick scientist J. Marvin Herndon. He also believes the Earth is expanding and he rejects plate tectonics. Despite that, mainstream science did not ignore him but enthusiastically tested this georeactor theory.

    Gando, A. et al., 2011. Partial radiogenic heat model for Earth revealed by geoneutrino measurements. Nature Geoscience 4(9), 647-651.

  • by mbkennel (97636) on Thursday February 02, 2012 @05:17PM (#38907887)

    "If you want to think like a scientist, try thinking about what might DISPROVE the global warming hypothesis. That's right - you'll find that NOTHING is accepted as disproof."

    That's false. What would disprove it?

    *) Measuring infrared fluxes in the atmosphere and finding that they aren't changing as predicted by our chemistry and current knowledge of infrared scattering. This experiment has been done and the results match predicted theory.

    *) space probes finding Venus to be just a bit warmer than Earth instead of the hell hole that it is.

    *) clear global cooling trends

  • by mbkennel (97636) on Thursday February 02, 2012 @05:25PM (#38908021)

    Huh?

    The knowledge and certainty level about nuclear georeactors is quite low (understatement), and it is a minority opinion that it exists. If it does we certainly don't know enough about its prehistory either and what the consequences to climate would have been, so the climatological record isn't remotely conclusive on this.

    http://en.wikipedia.org/wiki/Earth's_energy_budget#Incoming_energy [wikipedia.org]

    Incoming solar radiation is 173 petawatts, 44 to 47 terawatts from "stored heat and radioactive decay" (probably not from fission), which is 0.025%.
    So a variation of 4 terawatts is about 0.002% of solar insolation. Now the climate can be sensitive but I doubt it's that sensitive. It probably wouldn't be possible to pick up a fluctuation in a 4 terawatt core georeactor in climate data.

    The core georeactor should be actually reasonably easy to detect if you can analyze neutrino scattering data and get initial angle and energy distribution of the incoming particles. That fact that I haven't heard of such a signal (the neutrino experimentalists would have found an unusual pesky background that they couldn't get rid of when trying to measure solar neutrinos) leads me to believe far more directly and without reference to climate that it's unlikely there's any signifcant core georeactor. Maybe it's possible it was just missed, and was in the data.

    Atmospheric physics and dynamics is much, much better understood since we've had experiments and theory for 50 years or so.

  • by GrumpySteen (1250194) on Thursday February 02, 2012 @06:04PM (#38908565)

    It takes over 4 Joules of energy to raise the temperature of 1 gram of water by 1 degree Celsius. Your 22,964.4 Joule figure would be sufficient raise the temperature of 5.5 liters of water by 1 degree C.

    The earth's mass is slightly larger than 5.5 liters of water and thus requires slightly more energy to raise its temperature by one degree.

    Try again [wikipedia.org]

  • by Anonymous Coward on Thursday February 02, 2012 @06:07PM (#38908597)

    So how does that translate to 160 tonnes a year? The total mass of earth is estimated as 5.9721986×10^24 kg [wolframalpha.com] or 5.9721986×10^21 tonnes. To raise that mass by 1 C requires 22,964.44 J of energy.

    Ahem... 22,964.44 Joules of energy will not heat very much stuff up by 1 degree Celsius. That's less than the metabolic energy of 1 gram of fat. You missed something pretty important in your numbers.

    Regardless, this was not talking about raising the average temperature of the entire mass of the Earth, but an increat in the "surface temperature" of the earth. There's a pretty big difference. However....

    And it takes about 100 years to raise the temperature of earth by 1 C. So I'd say their math is way off.

    I imagine it would take a pretty long time to raise the temperature of the entire mass of the earth by 1 degree Celsius. Not a "don't blink, or you'll miss it" timeframe like 100 years.

  • by Chris Burke (6130) on Thursday February 02, 2012 @06:15PM (#38908685) Homepage

    Dude, your math is WAY off. How'd you go from mass to required energy without determining the specific heat of the earth?

    Here, let me calculate the energy required to heat just the iron content of the earth (34.6% by mass) by 1 C: 9.278* 10^26 J [wolframalpha.com], which is equivalent to 1.037 & 10^7 metric tonnes [wolframalpha.com].

    You are off by a LOT of decimal places. A mere 23kJ should have immediately tipped you off as not passing the smell test. That's less than 1/1000th [wikipedia.org] of the energy released by burning 1 liter of gasoline!

  • by CountBrass (590228) on Friday February 03, 2012 @02:50AM (#38912385)

    The most baseless claim in the summary is that there is a 5 mile wide sphere of Uranium acting as a nuclear reactor at the centre of the Earth.

    There is no evidence for this, it's just wild speculation.

You can do this in a number of ways. IBM chose to do all of them. Why do you find that funny? -- D. Taylor, Computer Science 350

Working...