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Do volcanoes emit more CO2 than humans?

What the science says...

Select a level... Basic Intermediate

Humans emit 100 times more CO2 than volcanoes.

Climate Myth...

Volcanoes emit more CO2 than humans

"Human additions of CO2 to the atmosphere must be taken into perspective.

Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day." (Ian Plimer)

The solid Earth contains a huge quantity of carbon, far more than is present in the atmosphere or oceans.  Some of this carbon is slowly released from the rocks in the form of carbon dioxide, through vents at volcanoes and hot springs. Volcanic emissions are a small but important part of the global carbon cycle. Published reviews of the scientific literature by Mörner & Etiope (2002) and Kerrick (2001) report a range of emission of 65 to 319 million tonnes of CO2 per year. Counter claims that volcanoes, especially submarine volcanoes, produce vastly greater amounts of CO2 than these estimates are not supported by any papers published by the scientists who study the subject. 

The burning of fossil fuels and changes in land use results in the emission into the atmosphere of approximately 34 billion tonnes of carbon dioxide per year worldwide, according to the U.S. Energy Information Administration (EIA). The fossil fuels emissions numbers are about 100 times bigger than even the maximum estimated volcanic CO2 fluxes. Our understanding of volcanic discharges would have to be shown to be very mistaken before volcanic CO2 discharges could be considered anything but a bit player in contributing to the recent changes observed in the concentration of CO2 in the Earth's atmosphere.

Volcanoes can—and do—influence the global climate over time periods of a few years but this is achieved through the injection of sulfate aerosols into the high reaches of the atmosphere during the very large volcanic eruptions that occur sporadically each century. But that's another story...

Recommended further reading on CO2 and volcanoes can be found here: Terry Gerlach in Earth Magazine ; USGS

Last updated on 2 June 2017 by John Cook. View Archives

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Further reading

Tamino has posted two examinations of the "volcanoes emit more CO2 than humans" argument by looking at the impact of the 1991 Pinutabo eruption on CO2 levels and the impact of past super volcanoes on the CO2 record.

The Global Volcanism Program have a list of all volcanoes with a Volcanic Explosivity Index (VEI) greater than 4 over the past 10,000 years.

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Volcano

Please check the related blog post for background information about this graphics resource.

Comments

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Comments 1 to 25 out of 236:

  1. A new sceptic argument that a "faith" based sceptic that I am arguing with currently has raised is that it is increased undersea volcanoes that are warming the oceans and therefore causing the current observed warming... I have not found too much to counter this apart from a few lines on Real Climate but those weren't too helpful - any suggestions?
  2. Undersea volcanos are indeed active but I don't think that is a big issue. The skeptical argument on volcanos has some merit but not in the way that they are explaining it. First, keep in mind that there are 2 and only 2 natural sources of heat on this planet. The first and more important is the sun. Block the sun and CO2 can have zero effect (it is a feedback). So you do have greenhouse conditions. Second is albedo, soot from volcanos and man-made sources collect over the poles, moreso over the north because that is where industry is largest. This lowers the albedo by darkening the ice. Less active volcanos in the northern hemisphere means that much less soot as well as other greenhouse gas emmitted from eruptions. Note that the south pole is not warming as much, nor south america or africa. The power of increased vulcanism is heat transfer to the ocean that causes upwelling currents and change the direction of air currents in doing so. The best known of these is El Nino/La Nina. See Johns "La Nina watch: March update" on this site.
  3. In rereading my comment I see that I misworded it. The entire first paragraph is the first source of heat and what increases it. The Second source of heat is the earth itself released by vulcanism or created by large forest fires. In both cases the soot while airborne will cool but once settled on the ice will warm as far as solar effects go. Both produce direct heat however and the second paragraph explains how internal heat controls weather.
  4. Recent articles indicate that AGW is not fully responsible for Greenlans glacial melts. von Frese explained. that "under a big place like Greenland or Antarctica, natural variations in the crust will makes some parts of the ice sheet warmer than others." from Magma May Be Melting Greenland Ice he also said "to effectively separate and quantify human impacts on climate change, we must understand the natural impacts too." "The researchers don't yet know how warm the hotspot is, but if it is warm enough to melt the ice above it even a little, it could enable the ice to slide more rapidly out to sea." from Volcano Deep Down Could Be Melting Greenland's Ice Since these articles were printed, I have seen none of the data from the stated conference that by now should be available.
  5. John Using a little circular logic I made a guess at where to place this comment. Sorry if I am incorrect. For starters Volcanoes Unleash El Niño. I had mentioned this in a couple of threads as there does not seem to be an EL Nino thread. But logically, since solar cycles stopped following warming in the late 70s (actually erratic weather conditions started then ie. the ice age scare of 1978-79) we need to take another look at the worst (hottest years) since: 1997-1998 El Niño 1982-1983 El Niño I would like to point out that the triggering and actual cause is volcanic/vulcanism and that these severe cycles must also include the La Nina events that follow each El Nino event. I would also like to point out that prior to the late 1970s there was very little mention of these climate cycles (in the US) other than California where they are very noticeable due to the lack of drastic seasonal changes.
  6. A graphic representation of this volcano induced phenomena showing both cooling and warming recent history clearly shows why 1998 was so hot and the cooling afterward.
    Response: I fixed your hyperlink (make sure it starts with http:// - you had the word at in the a href code. Interesting page - I especially like the little dig they have at NCEP to demonstrate how much better their forecast is.
  7. Some evidence: "Healy Researchers Make A Series Of Striking Discoveries About Arctic Ocean" — Contrary to their expectations, scientists on a research cruise to the Arctic Ocean have found evidence that the Gakkel Ridge, the world's slowest spreading mid-ocean ridge, may be very volcanically active. They also believe that conditions in a field of undersea vents, known as "black smokers," could support previously unknown species of marine life ScienceDaily (Nov. 29, 2001) "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean" — A research team led by the Woods Hole Oceanographic Institution (WHOI) has uncovered evidence of explosive volcanic eruptions deep beneath the ice-covered surface of the Arctic Ocean. Such violent eruptions of splintered, fragmented rock--known as pyroclastic deposits -- were not thought possible at great ocean depths because of the intense weight and pressure of water and because of the composition of seafloor magma and rock. ScienceDaily (June 26, 2008) I would think that this is an indication of increased vulcanism.
  8. John A little more detail here. "A major part of Earth's volcanism happens at the so-called mid-ocean ridges and, therefore, completely undetected on the seafloor." Bathymetric chart of the Gakkel Ridge (Nice photo and charts)
  9. The current work on vulcanism in the south Pacific: Olsen et al. Rapidly changing flows in the Earth’s core. Nature Geoscience 1, 390 - 394 (2008) Published online: 18 May 2008 | doi:10.1038/ngeo203 Subject Category: Geomagnetism, palaeomagnetism and core processes Rapidly changing flows in the Earth's core Nils Olsen & Mioara Mandea A large part of the Earth's magnetic field is generated by fluid motion in the molten outer core. As a result of continuous satellite measurements since 1999, the core magnetic field and its recent variations can now be described with a high resolution in space and time. These data have recently been used to investigate small-scale core flow, but no advantage has yet been taken of the improved temporal resolution, partly because the filtering effect of the electrically conducting mantle was assumed to mask short-period magnetic variations.. Here we show that changes in the magnetic field occurring over only a few months, indicative of fluid flow at the top of the core, can in fact be resolved. Using nine years of magnetic field data obtained by satellites as well as Earth-based observatories, we determine the temporal changes in the core magnetic field and flow in the core. We find that the core flow is spatially localized and involves rapid variations over a few months, with surprisingly large local accelerations. Our results suggest that short-term fluctuations of the core magnetic field are robust features of rapid core dynamics and should be considered in the development of future numerical models of the geodynamo. Danish National Space Center/DTU and Niels Bohr Institute at Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Correspondence to: Nils Olsen1 e-mail: nio@space.dtu.dk
  10. Sorry the subject of comment 9 is the south Atlantic, although it also affects the south pacific.
  11. Buried Volcano Discovered in Antarctica By Dave Mosher, LiveScience Staff Writer 20 January 2008: “This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet," Vaughan said. "The flow of this glacier towards the coast has speeded up in recent decades, and it may be possible that heat from the volcano has caused some of that acceleration."
  12. Three relevant articles: This one may have helped cooling last winter to some extent: "Kamchatka Volcano Blows Its Top", ScienceDaily (July 5, 2007) "The eruption of one volcano will have far-reaching affects. Although Klyuchevskoy is located in Kamchatka, its ash crossed the Bering Sea and reached Unimak Island in the Aleutians within one day." This one explains why not all eruptions cool: "Chile's Chaiten Volcano One Of Scores Of Active Volcanoes In Region", ScienceDaily (May 7, 2008) "In to order to significantly affect the climate, a volcano has to put out a lot of sulfur dioxide aerosols into the stratosphere for an extended period, which then reflects sunlight away from the Earth," he said. "Our data from Chaiten showed the last eruption was high in silica and low in sulfur." This most recent one may be on the same tectonic plate as Kamchatka (a different article that can be found on the same web page): "Explosive Eruption Of Okmok Volcano In Alaska", ScienceDaily (July 21, 2008) "Okmok Volcano in Alaska continues to produce explosions and ash plumes through a newly created vent and poses hazards to air travel in the area. ... There are about a dozen cones within the modern caldera that formed in the last 2000 years, and the most recent eruptive activity occurred in 1945, 1958 and 1997." Just 3 (somewhat large) examples of current vulcanism and why it may or may not be involved in cooling. My point being that not all vulcanism is created equal so a generic statement about volcanos is not relevant.
  13. John A little more support for my hypothesis: Tectonic Plates Act Like Variable Thermostat ScienceDaily (Aug. 14, 2007) — Like a quilt that loses heat between squares, the earth's system of tectonic plates lets warmth out at every stitch. Adapted from materials provided by University of Southern California.
  14. Hi Quietman. I went through all your volcanic links above. Generally, it seems that there have been new and interesting discoveries, but nothing establishes a change over recent decades in volcanic activity under ice that would correspond to recent climate changes, etc... ----------- "Magma May Be Melting Greenland Ice" http://www.livescience.com/environment/071213-greenland-magma.html "The newly discovered hotspot, an area where Earth’s crust is thinner"... "What caused the hotspot to suddenly form is another mystery."... I don't think hotspots form 'suddenly' (on the relevant timescale for recent climate changes, at least). It was newly discovered. The second quote above may be an example of careless word choice. What caused the ice stream to form (suddenly?), where it previously did not exist? It could have been global warming. What caused it to form where it did? In that matter, geology could be a factor. ------------------ "Volcano Deep Down Could Be Melting Greenland’s Ice" http://www.medindia.net/news/Volcano-Deep-Down-Could-Be-Melting-Greenlands-Ice-30702-1.htm discussion of 'variations' in geological heating seem to be about spatial variations, not temporal. ------------------ "Study: Volcanoes Unleash El Niño" http://dsc.discovery.com/news/afp/20031117/elnino.html Very interesting. But the causal link is through the already-known-to-be-important volcanic aerosol cooling (I had no idea that's what you were refering to in our previous discussion at "Science and Society"). And the impression I get here is that volcanic aerosols are not generally necessary or necessarily sufficient to cause El Nino conditions. There isn't a mention of a recent trend in that kind of eruption (explosive tropical) or ENSO either - although from the graphs on this website, there seems to be a period of greater volcanic aerosol abundance from ~1960 to the 1990s, after a period of relatively low volcanic aerosol abundance from ~ 1910 (or earlier in the Southern Hemisphere) to ~ 1960. Does this correlate with any ENSO (El Nino) behavior changes? Even if the answer is yes, there are other changes that would or could affect ENSO - some change in solar forcing, changes in human aerosols, both globally and also I would think in spatial distribution, and the anthropogenic increase in greenhouse forcing. There are other modes of internal variability, and while I don't know of specific interactions or explanations, it doesn't require a stretch of the imagination to suspect that monsoons (also affected by aerosols, not that others are not), MJO, QBO, and NAO, NAM, SAM, etc. could be pushing some of ENSO's buttons. I think such a thing as ENSO might be a general expectation for sufficiently wide (east-west) and large oceans along the equator - I've heard that a climate model may produce ENSO like behavior if the Atlantic is widened sufficiently. In the sense that a computer model is a theory, I think there is a theoretical explanation for ENSO at least in general. In so far as what human minds have comprehended, I don't know how far the understanding goes, but I know that typically trade winds push water westward in the tropics, building up a warm pool in the western part of a tropical ocean, and lifting the thermocline in the eastern part - potentially enough to allow upwelling of cold deep water. If a perturbation causes the winds to let up, the warm water may slosh back, and that changes the thermal forcing of the winds, which could allow continued weakenning of the winds, etc. - and the reverse could happen too, it's a positive feedback either way. There are many complexities to add to that picture (double ITCZ in western Pacific, equatorial Kelvin waves, equatorial countercurrent and equatorial upwelling, Ekman pumping), which I am not qualified to go into in so far as ENSO is concerned, but I can speculate that perhaps the temperature difference between the cold upwelling water in the east and the warm pool in the west has to reach some threshold before the positive feedack is strong enough to overcome some other effects that would tend to maintain steadier winds - and a longer period of time for a westward current to remain in low latitude waters could allow a higher temperature increase in the water along the way from regional radiative conditions (more sunlight - and when clouds form they have high tops in the tropics, so they have a stronger greenhouse effect than many clouds elsewhere, I think). ------------------ "Healy Researchers Make A Series Of Striking Discoveries About Arctic Ocean" http://www.sciencedaily.com/releases/2001/11/011129050111.htm Discovery of more volcanic/hydrothermal activity than was previously thought to exist - this does not mean a recent change in that activity has occured. ------------------ "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean ScienceDaily (June 26, 2008)" http://www.sciencedaily.com/releases/2008/06/080625140649.htm nothing about a recent change or any correlation to climate changes... ------------------ "Buried Volcano Discovered in Antarctica" http://www.livescience.com/environment/080120-antarctic-volcano.html An eruption occured 2300 years ago, volcano is still active. " “This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet," Vaughan said. "The flow of this glacier towards the coast has speeded up in recent decades, and it may be possible that heat from the volcano has caused some of that acceleration." " The article never states that an increase in geothermal heating in recent decades has been established, however. "Vaughan noted, however, that the hidden volcano doesn't explain widespread thinning of Antarctic glaciers."..." "This wider change most probably has its origin in warming ocean waters," he said, which most scientists attribute to global warming resulting from human activity, such as the use of fossil fuels. " ------------------ "Kamchatka Volcano Blows Its Top" (July 2007) http://www.sciencedaily.com/releases/2007/07/070705110230.htm "Chile's Chaiten Volcano One Of Scores Of Active Volcanoes In Region" http://www.sciencedaily.com/releases/2008/05/080507105654.htm "Explosive Eruption Of Okmok Volcano In Alaska" http://www.sciencedaily.com/releases/2008/07/080720093810.htm Yes, the location and composition of volcanic eruptions as well as the size/kind of eruption are factors in any climate/weather effects. The greatest cooling can be generally expected from low latitude volcanos because they are most likely to produce a global blanket of long-lived (for aerosols) stratospheric aerosols. Higher latitude eruptions' aerosol distributions may be less likely to cross hemispheres, and the stratospheric circulation each winter tends to bring air toward the poles and then back to the troposphere, so high latitude aerosols may come out of the stratosphere faster. Ash from high latitude eruptions may, depending on exact location, have some chance of landing on snow or ice, reducing the albedo and thus having a local or regional heating effect which would contribute to a global warming effect (until either the snow or ice melts - except for the albedo effect of the earlier melting time if that is involved - or enough new snow or frost falls/forms on top of it). On the other hand, I think any ash cloud hanging over most surfaces except snow and ice would increase the albedo and have a cooling effect, and then there is also the albedo effect of aerosols via their effects on clouds - these effects being more short lived. There is no indication here of a significant change in volcanic activity in recent decades from the previous decades or centuries or beyond. ------------------ "Tectonic Plates Act Like Variable Thermostat" http://www.sciencedaily.com/releases/2007/08/070813171122.htm direct geothermal heat supply still generally wouldn't significantly affect climate, especially global climate, during most of Earth's history except near the beginning. But this could be related to changing rates of geologic outgassing of CO2 over millions of years. ------------------ IN ADDITION TO THE ABOVE: I also found: ------------------ "Could Volcanic Activity In West Antarctic Rift Destabilize Ice Sheet?" http://www.sciencedaily.com/releases/2008/02/080229183818.htm very interesting. no suggestion of current activity or timing of activity in recent geological past. ------------------ "First Evidence Of Under-ice Volcanic Eruption In Antarctica ScienceDaily (Jan. 22, 2008)" http://www.sciencedaily.com/releases/2008/01/080120160720.htm a volcano erupted 325 BC and remains active. "Co-author Professor David Vaughan (BAS) says,"This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet. The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters." " ------------------
  15. Patrick Yes, I linked to Neds blog because you make an interesting argument in the Bertha thread. I thought that John and some of the other posters here would also find it so. On the arctic volcanos, these were new massive undersea eruptions in 1999-2001 along the arctic ridge, this relates to NEW increased seafloor spreading. The 2007 article on tectonics supports this and the subsequent additional heat convection currents concept. The current hypothesis on the cause of ENSO is not the volcanic eruptions, that is symptomatic not cause, the cause is undersea volcanic vents along the subduction zone as explained in the tectonics article. The aerosol issue is not involved in my argument because not all volcanos produce them or outgas the same compounds. SO2 outgassing hss a different effect than CO2. Particulates from undersea eruptions do not reach the atmosphere. SO2 and CO2 released by these submerged volcanos have two dramatic effects: convection currents and acidification of the ocean (something blamed on AGW but actually volcanic in origin). Recent tectonic activity has been observed under antarctica recorded as earthquakes along the transantarctic mountains (an ancient fault line or plate edge). The thinning of the crust under Greenland is directly related to it's active volcanos, mountain growth and seafloor spreading or rifting. These are like puzzle pieces, each one is not very significant in itself. but added together, along with what little we understand about gravitational stresses, begins to make some sense of what occurs in very long climate cycles.
  16. Patrick From "Could Volcanic Activity In West Antarctic Rift Destabilize Ice Sheet?" (the first one you found): "However, this study also shows that the land in West Antarctica has been rising beneath the ice sheet in some areas and subsiding beneath it in others, over roughly the past 25 million years. Some areas have subsided to as much as 8500 feet below sea level. This tectonic restlessness contrasts markedly with the stability of the regions that lay beneath the northern hemisphere ice sheets of the recent geologic past, and its affect on the history of the West Antarctic ice sheet has not yet been evaluated." This relates again to the tectonics article linked to in my comment (13).
  17. Quietman - I went back and looked - it appears I did skip over the link from your comment 8. When I click on there now, though, it takes me to a list of other science (and politics about science) blogs (which sidetracked me because they were interesting). Aside from that, nowhere did I see in any of the links you supplied here a claim of some recent change in geologic activity - the closest being speculation that changes could be occuring related to an ice stream in Greenland (doesn't apply to all of Greenland) and the Pine Island glacier (doesn't apply to all of West Antarctic ice sheet) - neither of which are affirmed as being due to a recent change in geological forcing - so it is still quite possible that any recent changes there could be due to changing climate, with some such locations perhaps being more sensitive or having different thresholds because of a constant geological factor. I interpreted other articles (such as those concerning explosive submarine eruptions or the mid ocean ridge in the Arctic) as being new discoveries - not indicating a change in the actual thing that had been discovered. (If there is some quote to contradict that which I missed please point it out to me). "The current hypothesis on the cause of ENSO is not the volcanic eruptions, that is symptomatic not cause, the cause is undersea volcanic vents along the subduction zone as explained in the tectonics article." I missed any such connection made between submarine volcanic activity and ENSO behavior - could you provide the quote from the article? (I'm not saying that geothermal heating itself wouldn't have some effect, but I think (those calculations I did at "Science and Society") that except in some rare extreme cases, the temporal variation on such short timescales would be miniscule compared to so many other available variations that might trigger or modulate ENSO behavior. I don't think compositional fluctuations from hydrothermal vents would have big enough effect (such as on buoyancy, on a large-enough spatial scale) to be significant in ENSO either. ..."not all volcanos produce them"... [aerosols] ..."or outgas the same compounds." Agreed. "SO2 outgassing hss a different effect than CO2." Agreed. "Particulates from undersea eruptions do not reach the atmosphere." Agreed. "SO2 and CO2 released by these submerged volcanos have two dramatic effects: convection currents and acidification of the ocean (something blamed on AGW but actually volcanic in origin)." Well, no I disagree strongly there. First, it isn't AGW itself, technically, but the emission of CO2 that is a major cause of AGW, that is directly causing ocean acidification as well (not that climate itself can't affect (bio)geochemistry, but in this case I don't think that's a big factor). Second, the amount of CO2 geologically outgassed is miniscule compared to anthropogenic emissions, and more importantly, it didn't change a lot just recently (on a timescale to matter to AGW, or even to glacial/interglacial variations). The long term SO2 emission rate probably isn't changing much either. Of course there are short-term variations, like single eruptions, but overall these are relatively constant fluxes, and so biogeochemical conditions will long since have responded to them until fluxes balance, so there is a steady state on intermediate time scales. "Recent tectonic activity has been observed under antarctica recorded as earthquakes along the transantarctic mountains (an ancient fault line or plate edge)." Now, that's interesting. But even if it were unusual in the last 100 or 200 years, is it unusual in the last few thousand years? "The thinning of the crust under Greenland is directly related to it's active volcanos, mountain growth and seafloor spreading or rifting." But that's not the kind of thing that happens quickly. My overall point being that there isn't evidence of changes in geological activity over such a time period such that they would be causing a significant part of the climate change over the last decades or even centuries (except for explosive volcanism into that air that produces aerosol cooling, which is accounted for by climate theory and models), and also, there isn't really a reason to suspect it as a significant factor. But of course a relatively constant geological condition, such as a hotspot under a part of greenland, could have an effect on the response to climate change, such as the response of overlying ice to warming at the ice surface and above.
  18. Patrick Unfortunately the ENSO hypothesis I had put in my notes but I did not write down the source. At the time I was looking to find out what drives El Nino for my own knowledge so it was not important to me to note the source. I remember it was a dot-gov site and I searched for "el nino". Re: Not happening quickly. There is an article at ScienceDaily.com (or LiveScience.com) that explains why we need to rethink rates of change for the earth. It seems that the earth works in spurts. Sometimes no action, sometimes slow and sometimes quickly. One was on "continental drift" (tectonic activity) rate changes and another on mountain building at subduction zones. So yes, geologically speaking these things can happen quickly, we just don't take notice of the changes unless we happen to be monitoring them (and we have not been for very long).
  19. " Sometimes no action, sometimes slow and sometimes quickly. One was on "continental drift" (tectonic activity) rate changes and another on mountain building at subduction zones. So yes, geologically speaking these things can happen quickly," but how quickly is quickly?
  20. Patrick That is the subject of my studies of late and the reason for my interest in the work done by Fairbridge. There are many point in earth's history where there were abupt changes. How abrupt these events were is totally unknown but assumed to take time because we thought that planetary evolution was both constant and steady. We now find that abrupt changes can happen very quickly. I think within a human lifetime as it would explain the rapid changes of the past but obviously this needs to be studied further.
  21. PS One important factor when considering tectonic movement is that it is not entirely in the horizontal plane but also in the vertical. Portions rise while others fall and this can affect movement measured horizontally as well.
  22. Re: "direct geothermal heat supply still generally wouldn't significantly affect climate, especially global climate, during most of Earth's history except near the beginning." It drives the ocean currents and in turn the air currents, ie. ENSO, PDO, AMO, etc. are driven indirectly by tectonics, hence the climate itself.
  23. "I think within a human lifetime as it would explain the rapid changes of the past but obviously this needs to be studied further." A number of sudden sharp changes can happen within seconds but they are limited in magnitude and spaced in time. Mantle convection and continental drift/plate movements are measured in cm or in per year - that's not to say there isn't variance, but the conditions driving and shaping mantle convection cannot change rapidly, and it's not going to get up to tens of meters per year (except if you go back in time far enough when the mantle's viscosity was suffiently low due to higher temperatures... that's probably closer to the beginning of the Earth than to now.) More rapid vertical movements can occur on smaller spatial scales, I think, but again, there are limits. (I expect the larger horizontal scale vertical motions caused by variations in the underlying mantle to be more gentle.) The fastest continental drift that could happen would correspond not with mantle convection but with 'true polar wander', which has to do with moments of inertia - the asymmetry of the Earth about it's axis caused by a supercontinent elevated by a buildup of heat in the mantle beneath it, for example - whether or not this ever did become a large factor in geographic changes, I'm not sure - it has been hypothesized to have occured late in the Neoproterozoic. The rate at which this could occur for a given mass distribution can be calculated fairly well - it's just a question of what mass distribution is more or less likely. I don't think it would be fast enough to affect day-to-day life for most people if it happenned now, though I haven't read so much... "It drives the ocean currents and in turn the air currents, ie. ENSO, PDO, AMO, etc. are driven indirectly by tectonics, hence the climate itself." I still don't see a good reason to suspect that or evidence to support it, though.
  24. Patrick Re: "I don't think it would be fast enough to affect day-to-day life for most people if it happenned now" No more than the normal "wobble" that has been the norm for human existance on this planet, Ice Age 4 included. We almost went extinct once already. For supporting evidence for actions of oscillations you can check the threads on this site. John has written a few good posts on them. The origin is another matter as it is still a hypothesis (just like AGW) but somewhat harder to find papers for on the web (not a popular subject like AGW). The hypothesis has just as much merit as the AGW hypothesis however. If I can relocate the original papers I will post links to them here.
  25. PS It isn't the speed of drift that is important, it's the vulcanism driving the drift which indicates a change in thermal energy released to the oceans.

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