"That could never happen." "It so totally could!"
February 28, 2010 2:59 AM Subscribe
Is there any way that major fluctuations in the Earth's climate could have an effect on the temperature of the Earth's core? What about its density? Could temperature changes cause some sort of change in the planet's gravity or magnetic fields? Could changing weather have any other effect on the Earth's interior?
This is to settle a debate.
This is to settle a debate.
Best answer: No, climate and weather effects on the surface of the Earth cannot affect the temperature or density of the Earth's core.
In the event of a major impact of an asteroid over 100 km across, the vaporization of rock would generate enough heat to vaporize the oceans. But studies (here's a small article [warning: PDF] by Norman H. Sleep - best I could do in a few minutes of web search) have shown that the thermal pulse from such a huge event would only penetrate down to a depth of 1 kilometer into the Earth's crust. Not only would the heat from such a huge event not make it to the core, it wouldn't even be enough to completely sterilize the planet - organisms that live in rock at depths lower than 1 km would survive.
If the heat from an impact event large enough to boil away the oceans wouldn't make it to the core, we can safely assume that the much smaller variations in climate would not be able to affect the core, either.
As for temperature changes affecting gravity - weather systems passing underneath (more specifically, variations in air pressure of those weather systems) could have very, very minor effects on the pull of gravity for an object at considerable altitude; these effects would not exist, however, for a person standing on the surface (as the weather system would be above them). None of this would be because of any changes in the Earth's interior - for an object high above the surface it would be because of variations in the amount of mass between it and the center of the earth.
posted by Chanther at 3:30 AM on February 28, 2010 [2 favorites]
In the event of a major impact of an asteroid over 100 km across, the vaporization of rock would generate enough heat to vaporize the oceans. But studies (here's a small article [warning: PDF] by Norman H. Sleep - best I could do in a few minutes of web search) have shown that the thermal pulse from such a huge event would only penetrate down to a depth of 1 kilometer into the Earth's crust. Not only would the heat from such a huge event not make it to the core, it wouldn't even be enough to completely sterilize the planet - organisms that live in rock at depths lower than 1 km would survive.
If the heat from an impact event large enough to boil away the oceans wouldn't make it to the core, we can safely assume that the much smaller variations in climate would not be able to affect the core, either.
As for temperature changes affecting gravity - weather systems passing underneath (more specifically, variations in air pressure of those weather systems) could have very, very minor effects on the pull of gravity for an object at considerable altitude; these effects would not exist, however, for a person standing on the surface (as the weather system would be above them). None of this would be because of any changes in the Earth's interior - for an object high above the surface it would be because of variations in the amount of mass between it and the center of the earth.
posted by Chanther at 3:30 AM on February 28, 2010 [2 favorites]
IANASeismologist, volcanologist, geologist, or mineral chemist. But until one chimes in, I'd say it's a question of what you mean by "effect". Defined one way, of course there'd be some effect. Consider two Earths, identical except that the atmosphere of one is 2-3 degrees hotter in places than that of the other, and moves in slightly different ways. Will the insides of both be exactly the same? There's no magic insulating layer that shields the core 100% from the surface, so of course there'd be some difference (even if it's only 1x 10^-20 of a degree in one tablespoon of rock).
On the other hand, if what you're asking about is crazy disaster scenarios like observable shifts in gravity, etc., then I doubt it. Global warming involves mostly very tiny shifts in temperature-- like, single degrees one way or the other. The core, on the other hand, is approximately 4,000-6,000 degrees C in temperature, and thousands of kilometers down. So to posit a measurable effect seems a little like saying the weather the next state over might affect the temperature of your oven.
posted by Bardolph at 3:33 AM on February 28, 2010
On the other hand, if what you're asking about is crazy disaster scenarios like observable shifts in gravity, etc., then I doubt it. Global warming involves mostly very tiny shifts in temperature-- like, single degrees one way or the other. The core, on the other hand, is approximately 4,000-6,000 degrees C in temperature, and thousands of kilometers down. So to posit a measurable effect seems a little like saying the weather the next state over might affect the temperature of your oven.
posted by Bardolph at 3:33 AM on February 28, 2010
The oceans have a mass about 5,000 smaller than that of the solid earth. The atmosphere has a mass about 1,000,000 times smaller than the solid earth. All three have heat capacities that are approximately equal (to within a factor of a few), the amount of energy in the earth's climate (including the ocean) is simply not going to make any detectable difference to the earth's interior. A heating of the atmosphere and ocean of say, 10C, is going to have absolutely no effect on the core, the magnetic fields, solid density, etc.
posted by caek at 3:35 AM on February 28, 2010
posted by caek at 3:35 AM on February 28, 2010
There is one way global warming will have an effect on the physical earth, though not something noticeable without instruments. Much of the frozen water overlaying land is at high latitudes. This water when it melts will be somewhat evenly distributed over the world oceans which will slow the rotation of the earth. Also it's only somewhat, the water will actually favour low latitudes which again will slow the rotation of the Earth.
Finally places that are currently under ice will experience a very small rise in elevation because of the overburden being reduced in mass. In the western arm of the Alps, for instance, mountains are growing at a rate of .035 inches per year.
posted by Mitheral at 4:49 AM on February 28, 2010 [1 favorite]
Finally places that are currently under ice will experience a very small rise in elevation because of the overburden being reduced in mass. In the western arm of the Alps, for instance, mountains are growing at a rate of .035 inches per year.
posted by Mitheral at 4:49 AM on February 28, 2010 [1 favorite]
The Earth weighs approximately 5.9736 × 10^24 kg.
That's 5,973,600,000,000,000,000,000 metric tons. In other words, if you removed 1 million metric tons of mass from the Earth every second, it would take millions of years to have any appreciable effect on its mass, and billions to remove it completely.
The question is whether relatively minor changes in the temperature of Earth's atmosphere, which at its heaviest weighs on the order of grams per liter, will have a pronounced effect, however minor, on the physical characteristics of the Earth.
I don't even think you need to do the math here.
posted by valkyryn at 5:29 AM on February 28, 2010 [2 favorites]
That's 5,973,600,000,000,000,000,000 metric tons. In other words, if you removed 1 million metric tons of mass from the Earth every second, it would take millions of years to have any appreciable effect on its mass, and billions to remove it completely.
The question is whether relatively minor changes in the temperature of Earth's atmosphere, which at its heaviest weighs on the order of grams per liter, will have a pronounced effect, however minor, on the physical characteristics of the Earth.
I don't even think you need to do the math here.
posted by valkyryn at 5:29 AM on February 28, 2010 [2 favorites]
Everyone here is right. Another way to look at it is that surface temperatures can and do affect the temperature of the earth's crust. Not by a whole lot (even permafrost only gets about 15 feet deep according to wikipedia), but the effect is there, even down to a few kilometers. Look at this quick article on the Geothermal gradient. So that tells us there's a signal in the first couple of km, but what about the rest of the 6000+ km?
Right under the crust is the mantle, a fluid layer almost 3000 km thick. The coolest the mantle gets is about 500 degrees C at the boundary layer with the crust. All of that heating is due to the enormous pressure and friction going on there, clearly not forcing from the crust. Even if somehow you can heat the deep crust up a few degrees C (which would take thousands of years to propagate that far, based on talks I've heard), such an effect would be washed away at the crust-mantle interface. Since the core is another 3000 km deeper and under yet higher forces due to yet higher pressures, it can't see any information about what's going on at the crust. Magnetic fields come out of core-mantle interactions, and neither of those would be affected either.
posted by Schismatic at 6:49 AM on February 28, 2010
Right under the crust is the mantle, a fluid layer almost 3000 km thick. The coolest the mantle gets is about 500 degrees C at the boundary layer with the crust. All of that heating is due to the enormous pressure and friction going on there, clearly not forcing from the crust. Even if somehow you can heat the deep crust up a few degrees C (which would take thousands of years to propagate that far, based on talks I've heard), such an effect would be washed away at the crust-mantle interface. Since the core is another 3000 km deeper and under yet higher forces due to yet higher pressures, it can't see any information about what's going on at the crust. Magnetic fields come out of core-mantle interactions, and neither of those would be affected either.
posted by Schismatic at 6:49 AM on February 28, 2010
One comparison I heard years ago (probably on Bill Nye the Science Guy) was that from the depths of the oceans to the top of the atmosphere and everything in between was relatively no thicker than a single layer of plastic wrap around a basketball. So essentially everything that humans have ever done or experienced (obviously excluding space travel)? Nothing more than plastic wrap on a basketball.
posted by carlh at 7:29 AM on February 28, 2010
posted by carlh at 7:29 AM on February 28, 2010
For another comparison, here are some quick facts on temperatures in caves.
The flow of heat through the sandstone and limestone overlying Wind Cave's passages is extremely slow. Temperature fluctuations of over 60°F between day and night are not uncommon on the surface, but if we were to monitor the temperature only two feet below the surface on such a day, the fluctuation in temperature would be only about 1°F.
posted by gimonca at 7:37 AM on February 28, 2010
The flow of heat through the sandstone and limestone overlying Wind Cave's passages is extremely slow. Temperature fluctuations of over 60°F between day and night are not uncommon on the surface, but if we were to monitor the temperature only two feet below the surface on such a day, the fluctuation in temperature would be only about 1°F.
posted by gimonca at 7:37 AM on February 28, 2010
I love to hear the mechanism the person who thought this would work was imagining.
posted by DU at 7:38 AM on February 28, 2010
posted by DU at 7:38 AM on February 28, 2010
Response by poster: I love to hear the mechanism the person who thought this would work was imagining.
posted by DU at 10:38 AM on February 28 [mark as best answer]
[+] [!]
It was something along the lines of the whole Earth being a sort of an organism, so everything could affect everything else, and the heat had to travel somewhere and a bunch of other stuff I don't remember. I don't think he had an actual idea of "this is how it could happen," but more of a "it really seems like this could maybe happen somehow" type thing. Thanks to all who answered.
posted by Captain Cardanthian! at 10:26 AM on February 28, 2010
posted by DU at 10:38 AM on February 28 [mark as best answer]
[+] [!]
It was something along the lines of the whole Earth being a sort of an organism, so everything could affect everything else, and the heat had to travel somewhere and a bunch of other stuff I don't remember. I don't think he had an actual idea of "this is how it could happen," but more of a "it really seems like this could maybe happen somehow" type thing. Thanks to all who answered.
posted by Captain Cardanthian! at 10:26 AM on February 28, 2010
What about its density?
The IPCC report predicts up to 1/2 meter of sea level rise this century due to the thermal expansion of sea water as it warms.
posted by JackFlash at 11:40 AM on February 28, 2010
The IPCC report predicts up to 1/2 meter of sea level rise this century due to the thermal expansion of sea water as it warms.
posted by JackFlash at 11:40 AM on February 28, 2010
This thread is closed to new comments.
The tremendous heat and mass and relative chemical stability make the earth's core far, far more stable than the puny crust on which we eke an existence, with its melange of chemicals, exposure to radiations of all spectrums and volatile interactions. It operates not in centuries, or even millennium, but in ages.
In short, no.
posted by smoke at 3:29 AM on February 28, 2010 [1 favorite]