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Comments 131051 to 131100:

131051. Patrick 027 at 15:09 PM on 23 September 2008
        Volcanoes emit more CO2 than humans
        "When the amplitude of the wave becomes significant compared to fluid depth, there are nonlinearities" And also when the displacements become significant compared to the wavelenth... --- "PS - It's NASA that claims CO2 induced AGW is only 2% of GHG warming. I don't know how they arrived at that number. " Maybe they're comparing the anthropogenic forcing from the increase in CO2 to the total greenhouse forcing that exists (I think something like 155 W/m2, although that includes feedbacks (water vapor and clouds) that maintain the climate as is in the absence of change)? I'll get back to sudden core motion changes tomorrow.
131052. Patrick 027 at 14:56 PM on 23 September 2008
        Volcanoes emit more CO2 than humans
        To be specific, 1.1 um/s (u used in leiu of 'mu'; um = micron) is the vertical tidal acceleration at the Earth's surface at points in line with the center of the Earth and the Moon, and is locally upward. The vertical tidal acceleration halfway in between those two points, in a ring on the surface, is downward and half the magnitude. Let 2*T be the vertical tidal acceleration on the surface of a sphere at the near and far point from a tide generating mass. Then, where N is the angle from near point (so N = pi radians (or 180 degrees) at the far point), The local vertical tidal acceleration is: dv = T * [ 1/2 + 3/2 cos(2N) ] And the local horizontal tidal acceleration (positive toward lower N): dh = T * 3/2 sin(2N) So the total range of each is 3T. T is linearly proportional to the distance to the center of the sphere experiencing the tides, and does not depend on the mass of the body experiencing the tides**. The shape and magnitude of the equilibrium tidal distortion can be determined by finding the surface for which the vector sum of the tide experiencing body's gravity and the tidal acceleration are normal (perpendicular) to that surface - the slope of that surface is thus dh/(g-dv) (or the negative of that, depending on perspective), which is almost equal to dh/g since |dv| << |g| **. **-thus far I have ignored the effect of the gravity of the mass anomaly of the tidal bulge itself. This would tend to make the tides a bit larger. When I tried to calculate the equatorial bulge in the same way I got half the actual value, so maybe the actual tidal bulge is twice what I have said so far - at equilibrium, that is (??). However, actually figuring out how a body is deformed is tricky (without knowing more than I do, anyway). The vertical tidal acceleration is related to increased spacing of (geo)potential surfaces - surfaces of constant potential energy - caused by the shape of the bulge. At equilibrium, density variations are only perpendicular to these surfaces. One could imagine a combination of vertical and lateral movement to shift the body around into this shape. As the potential surfaces are spaced differently, the pressure increase with depth increases at a different rate, so that density changes due to pressure changes should fit. However, one could also imagine a response involving initial decompression at high tide and compression at low tide (in response to the vertical tidal acceleration) - a sharp density discontinuity could shift up and down to match the equilibrium shape, but then the mass distribution below that point would not be at equilibrium The pressure variations at depth would then drive lateral movements toward equilibrium. The equatorial bulge is essentially at equilibrium because it's not be cycled or varied rapidly. Tidal deformation is cycled as objects spin through the tidal acceleration and tidal potential energy fields. The tidal bulge must then travel as a gravity wave (or some other wave) around/through the object. A freely propogating gravity wave travels due to the pressure gradients in the fluid caused by a vertical surface displacement through a fluid at a speed c = square root of (gH), where g is the gravitational acceleration and H is the fluid depth. It is a gravity wave because gravity supplies the restoring force. This formula is only true for a shallow fluid (compared to wavelength) which is below a vacuum or very low density material compared to itself, as is the situation for water waves under air. More generally, I think the speed is also proportional to the difference in densities across the surface divided by the density of the underlying fluid (this is an internal gravity wave). When the wavelength is not much longer, or is shorter, than the fluid depth, the full motion of the wave does not extend all the way down because (*I think - haven't done the math yet for myself*) vertical accelerations cummulatively cancel out the pressure variation due to the surface height displacements, so the wave only 'feels' some fraction of the fluid. When the amplitude of the wave becomes significant compared to fluid depth, there are nonlinearities... I don't think the compressibility of water has much effect on gravity waves, but more generally, gravity and elastic forces may both supply a restoring force. In solids, the elastic forces may include a resistance to shearing motion (as in a seismic S-wave, and also I think a 'Love' wave (kind of surface seismic wave) - (of course gravity is insignificant in S, P (compressional, like sound waves), Love, and Raleigh seismic waves). If and when the coriolis effect comes into play, there are also Kelvin waves, which are waves that move along lateral boundaries (like coastlines) with amplitudes that, in the case of constant fluid depth found immediately off the coast and a straight coastline (compared with the wavelength of the wave, I suppose), decay exponentially away from the coast. Such Kelvin waves travel at the same speed as gravity waves (at least in the case of wavlength >> fluid depth). There can also be inertio-gravity waves. Internal gravity waves also occur in a fluid with continuously varying density (the atmosphere), as opposed to a sharp interface - the math gets more complicated in that case. ... To make a long story short, there are certain natural frequencies of various modes of oscillation for the whole Earth, for ocean basins, etc, which depend on the size and shape and the speed and behavior of different kinds of waves. If a system is forced near it's natural frequency, it can resonate. If it is forced much faster than a natural frequency, there may not be much response. If the forcing is much slower, the system may just follow the forcing in near equilibrium (I think). My impression is that not much per unit volume deformation is required to distort the whole Earth by the tides because the horizontal movement is distributed over large vertical distances; the horizontal displacements would be of the same order of magnitude as the vertical displacements. Rather than coming back to it later, notice that implies a tidal strain (at equilibrium) (compressional, tensile, or shear) on the order of 50 cm / 6000 km, or ~ 0.1 ppm. I don't know what stress that would require within the crust offhand. If the whole Earth responded in the same way, the same would be true for the oceans - the vertical depth changes would be small because most of the surface changes would be supplied by changes in the sea floor (and there would be no noticeable changes at the coasts). But the ocean doesn't respond the same way, so the horizontal displacement in the open ocean may be on the order of a kilometer (which the coriolis force may act on so that water parcels move in loops). The changing water depth would also affect changes in the underlying crust and mantle, so it's complicated. Of the energy that is going into the tidal displacments, some comes back out - the 'elastic' fluid motion of the ocean (and outer core in as far as that's concerned), and the elastic deformation of the solid Earth (includes the mantle - it responds more rigidly to high-frequency cycling; plastic deformation takes time). Energy is lost to viscosity in fluid motions and in plastic deformation, electrical resistance in the core, and to any brittle failure that would occur, as well as microscopic fractures. (PS atomic spacing may vibrate about equilibrium spacing, where equilibrium is at the bottom of an 'energy well'. Over small vibrations the energy well is approximately parabolic, so there is a linear proportion of force to deformation (strain). But when atoms are pulled apart, the energy approaches a modest limit, whereas pushed in close enough and the energy shoots way up. Thus, extreme compression can store so much energy that when released, the atoms could fly apart (vaporization).) Anyway, not much tidal energy is lost outside the oceans on Earth. More energy may go into the solid Earth tides then is dissipated there because the energy can come back out to the extent that the Earth 'springs' back. -------------- At the surface of the sun, with all planets aligned, tidal acceleration is 0.981 ppt of the lunar tide on Earth's surface. That's on the order of 1 nm/s2. At 10 solar radii out from the center, it would be on the order of 10 nm/s2. I'm not sure how the solar wind's velocity varies as it moves away from the sun - it would be decelerated by gravity but it is also affected by the magnetic field (and vice versa). For the sake of having some ballpark figure: at 100 km/s, it takes ~ 7,000 seconds to cross a solar radius. In 70,000 seconds, the time taken to cross 10 solar radii, the tidal acceleration would make a difference in velocity on the order of 0.7 mm/s. Even out 100 solar radii, tidal acceleration might cause a variation on the order of 7 mm/s. It seems rather insignificant compared to a speed of even just 10 km/s, let alone 100 km/s or 500 km/s. Of course, while I've been mentioning tidal accelerations out to 10 Earth radii and 10 solar radii, I should mention that the formulas for tides I've been using are nice linearizations - approximations that will fail when the distance out becomes significant compared to the distance to the tide-generating mass. However, for a tide generating object a distance R from the center of the body experiencing tides, the approximation is not off by more than a factor of 10 within ~ 75 % of R toward the tide-generating mass, or ~5 times R in the opposite direction; it's not off by more than a factor of 2 within 1/3 R toward the tide-generator or just over half of R in the opposite direction.
131053. Patrick 027 at 11:47 AM on 23 September 2008
        Volcanoes emit more CO2 than humans
        Tidal motion: If a local tide h = A*sin(wt), where A is half of the range, the maximum rate of change of h would be A*w; w=2*pi*frequency; for the maximum possible semidiurnal lunar tide on Earth (where the moon is in the equatorial plane), the frequency (not adjusting for the moon's orbital motion, which would reduce the following numbers just a little) is roughly 2/(86400 s), so w = 2pi/(43200 s) = 0.000145 / s. Thus at the surface of the Earth, the maximum vertical velocity of an equilibrium tide is 0.039 mm/s; at the core/mantle boundary it would be about 0.012 mm/s (just over a tenth the typical fluid velocity in the outer core, and of even less importance to the geodynamo for other reasons). The corresponding velocity at 10 Earth radii from the Earth's center: 39 cm/s. The corresponding velocity on the surface of the Sun for all planets aligned, not adjusting for planetary motions, using a solar rotation period of 26 days (it's in that neighborhood, although it varies with latitude on the Sun): 5.8 microns per second. For what it's worth, the corresponding velocity at 10 solar radii from the Sun's center: 58 mm/s. But how would that pertain to the solar wind? What are tidal accelerations? Earth's surface g = ~ 9.81 m/s2 = G*massEarth/(radiusEarth^2) -- Moon's mass is about Earth's mass / 81 Moon's (average) distance from Earth is about 60.3 Earth radii. 1/81 * [(1/59.3^2)-(1/60.3^2)] = 0.12 ppm -- So the difference in lunar g from Earth's center to the sublunar point at Earth's surface, as a fraction of Earth surface g: 0.12 ppm. That's 1.1 microns per second squared. to be continued...
131054. Patrick 027 at 10:27 AM on 23 September 2008
        Volcanoes emit more CO2 than humans
        Specifically, about 89 % of the mass of the sun is within half it's radius from the center. This means that the size of the equilibrium tidal bulge above that point is nearly proportional to the fourth power of the distance from the center; and would only be close to 1/16 of it's surface value - more precisely, 1/(16*0.89) = 1/14.24 = 7.02 % of the surface value. At just 20% of the way to the center, only ~ 1 % of the mass of the sun lies above, so the equilibrium tidal bulge is rather close to 0.8^4 = 0.1^4 * 2^12 = ~ 41 % of the surface value. Keep in mind that the equilibrium lunar tide at the Earth's surface has a range of ~ 54 cm at the surface, or close to 16 cm at the core/mantle boundary (I say close to because while g is nearly constant in the mantle, it is not precisely constant); for what it's worth, at 10 Earth radii from the center of the Earth, it would be 5.4 km. If all the planets were aligned with the sun, the equilibrium tidal range at the sun's surface would be about 2.1 mm (close to how much your hair would grow in 5 in 6 days - and points on the sun would go through this range in a bit over 10 days, I think (half solar rotation period)) - at 20% below the surface, 0.86 mm; for what it's worth, at 10 times the solar radius from the sun's center, it would be 21 m (69 feet). to be continued...
131055. Philippe Chantreau at 06:19 AM on 23 September 2008
        The link between hurricanes and global warming
        Thanks Chris, nice to have someone with more awareness of the current litterature to give us pointers.
131056. Philippe Chantreau at 06:16 AM on 23 September 2008
        What does CO2 lagging temperature mean?
        The caveat in your argument is this adjective: valid. There is not that much criticism from skeptics that deserves it. Whatever is actually valid is being considered and is part of the scientific litterature. No offense, but you going for Beck's pathetic nonsense and plain lies does not indicate that your sense of what is valid is better than mine.
131057. Patrick 027 at 04:24 AM on 23 September 2008
        Volcanoes emit more CO2 than humans
        First two clarifications of what I wrote earlier: "So of the heat that goes into driving the convection, perhaps between 70 % and 85 % (halving the efficiency to approximate the effect of internal heat sources only) would then go on to the mantle." With just under 30 % conversion of heat to mechanical energy for the heat coming from the base of the outer core, with nearly linear temperature trend with depth and the temperature range being somewhat small compared to absolute temperature, a first approximation for a distributed source of heat within the outer core would be half that efficiency of conversion - just under 15 %. That heat would come from the overall temperature decline of the outer core. However, the volume per unit depth is not invariant but is proportional to the square of the radius. The mass distribution is a bit different because of increasing density toward the center (Karato p.13), and specific heat is not constant, but the distributed heat source from cooling would still likely be skewed toward the cooler parts of the outer core, so the overall efficiency for the conversion of heat from cooling would be less than half of the that of the latent heat from the base of the outer core from inner core growth. For my own curiosity I might sometime try to estimate the proportion of the two heat sources by comparing the "100 K every billion years would release 5.7 TW of heat" to a figure derived from specific heat - unfortunately a figure not easy to find for molten high pressure iron alloy. The other clarification: "Of course, some of the mechanical energy goes back into heat anyway, and some goes into electromagnetic energy, but some of that may go back into heat within the core (but I'm thinking it would go back into heat always at lower temperature (higher up within the core) than where it went into mechanical energy, so that entropy increases), ... etc." That's on average - that the mechanical and electromagnetic energy produced from heat at one temperature will on average go back into heat at a lower temperature - individual packets of energy may go back into heat at higher temperature, destroying entropy, provided other parts of the system are supplying the work (free energy) to drive such a process, and gaining entropy. In the absence of fluid motions, the magnetic field would decay - about exponentially - due to diffusion of the magnetic field. If the core were superconducting, this could not happen - any change in the magnetic field would produce a voltage that would drive an electric current that would restore the magnetic field. The finite conductivity of the material allows some of the electrical energy to go into heat, so that the magnetic field can diffuse and decay. According to Karato (pp.197-198 in particular), the magnetic field would essentially vanish in ten thousand years without a geodynamo to power it up. I would imagine the decay rate is used to estimate the power that must go into maintaining the field - this is rate of magnetic energy conversion to heat energy in the core itself. Because of uncertain toroidal field components in the core that are hard or impossible to detect directly from the surface (though they can be inferred by comparing the seismographic implications of different geodynamo computer models to seismographic observations, taking into account some inner core properties), the actual magnetic field energy density is uncertain, so that would be a source of uncertainty in the power necessary to maintain it. The magnetic field energy will be concentrated within the core - inferred from Karato p.199, the magnetic flux B in the core may be between ~ 3 and ~ 300 times the surface value (30 microTeslas) (B of a typical refrigerator magnetic is about 100 times the natural B at the surface). I think field energy density is proportional to the square of B, in which case the energy density is between 9 and 90,000 times the surface value, the volume of the core is ~ 16 % the volume of the Earth (more than 1/9) (for future reference, surface area of core ~ 30 % that of the whole Earth (which implies the mass of the core is about ~ 30 % the mass of the Earth, since gravitational acceleration is nearly constant within the mantle (that's somewhat of an accident of the specifics of the Earth's mass distribution, not a general principle)), radius of core ~ 54 % that of the whole Earth); the magnetic field changes wouldn't induce much of a current in the mantle and the mass of the magnetosphere and E-region dynamo are very small, so it makes sense to think that most of the geodynamo energy goes back into the heat energy of the core. Any mechanical and electromagnetic energy going back into heat within the core also includes that coming from composition-generated buoyancy. (But I think some small portion of electromagnetic energy must radiate away into space as the Earth moves and the field changes.) As long as I'm on this, notice that 'stretching' the field lines, contorting them by uneven fluid motions, increases the magnetic energy density by putting a greater length of field lines into a unit volume. An interesting analogy could be made between that and the conversion of potential to kinetic energy in the atmosphere to sustain nearly-geostrophic wind shear as isotherms are elongated (without changing the average temperature gradient), such as by a growing wave pattern. There are big differences but there's a cool geometric similiarity. --- "And then you need to add the extra gravitational forces from jupiter and full alignments. If they can affect the sun they can certainly effect the Earth." The vast majority of tidal forces on Earth is from the moon and sun (solar tides being about half the magnitude of lunar tides, I think (roughly from memory ratio of masses divided by cube of ratio of distances: ~330,000*80 * (0.384/150)^3 =~ 0.44 - just under half). Remember planetary tides on the sun from: http://blogs.abcnews.com/scienceandsociety/2008/07/global-warming.html#comments A more complete comparison: height of equilibrium tidal bulge raised on sun by planet, as fraction of that raised on earth by moon, [ignoring out-of-equilibrium complexities of crust,ocean reaction (no Bay of Fundy on sun?)] expressed as ppt (parts per thousand): Jupiter: 1.33 Venus:.. 1.27 Earth:.. 0.590 Mercury: 0.563 Saturn:. 0.0647 Mars:... 0.0179 Uranus:. 0.00122 Neptune: 0.000375 Pluto:.. 0.0000000191 SUM:.... 3.84 Tidal acclerations at solar surface generated by planets, as ppt of lunar tide on earth, : Jupiter: 0.340 Venus:.. 0.325 Earth:.. 0.151 Mercury: 0.144 Saturn:. 0.0165 Mars:... 0.00458 Uranus:. 0.000311 Neptune: 0.0000957 Pluto:.. 0.00000000488 SUM:.... 0.981 The sums would be approached when Venus and Jupiter and a few others are aligned or close to aligned with the sun. When Jupiter-Sun-Venus forms a right angle, the tides on the sun will be more limited. (PS notice Saturn plays a much larger role in the 'solar jerk' (where the importance of a planet is proportional to it's mass times it's distance) than it does in tides on the sun (mass divided by distance cubed). This would have some implications for Fairbridge's concepts. It would also be instructive to consider the product of the above numbers, which gives the tidal acceleration that acts on the tidal bulge: In ppm of equilbrium lunar tides on Earth: Sum of products:.. 1.04 Product of sums:.. 3.77 Jupiter by itself: 0.454 The distinction between the first two is a nonlinearity. This is the tidal force per unit area of the sun per unit density variation with depth at the sun's surface, relative to a theoretical equilibrium lunar tide on Earth. The density variation within the Earth is distributed with some significant concentration near the surface and near the core/mantle boundary. The mass of an equatorial bulge is produced by the vertical displacment of a density contrast. The density variation within the sun is quite small near the surface; one has to get almost halfway to the center before the density is comparable to the ocean, ~ 60 % of the way to the center to find densities similar to that of the Earth's mantle; the great majority of the Sun's mass is contained within half it's radius from the center. to be continued...
131058. chris at 21:39 PM on 22 September 2008
        Svensmark and Friis-Christensen rebut Lockwood's solar paper
        Re #4 Mizimi, Perhaps you need to look again and think a bit more carefully. John Cook explains it very straightforwardly in his article and the two graphs of Svensmark and Friis-Christensen rather speak for themselves. i.e. according to Svensmark and Friis-Christensen's analysis presented in the graphs above, changes in the CRF mediated by solar activity have made zero contribution to the warming of the last 30-odd years. If anything the CRF contribution is a slight cooling one.
131059. chris at 21:21 PM on 22 September 2008
        The link between hurricanes and global warming
        Re #10 and #14 (Mizimi and HealthySkeptic) Why should we take account of the appeals to authority of a 78 year old retired scientist just because he happened to be an authority on hurricanes during his working career? Gray is demonstrably wrong in many of his assertions, and as with all science, his comments should be judged according to the evidence, and not because he's given platforms for bombastic assertions, and you might happen to like what he says. If you look at the numbers that Gray asserts about hurricane numbers, for example (Mizimi reproduced these in post #10), you can see the first problem. As Gray presumably knows full well (after all he's published on the very subject - see Goldenberg et al, 2001 below), the issue is not about total numbers/frequencies of hurricanes and tropical storms, but the increased numbers of high category (Cat 4 and 5) storms in a warming world. That's pretty obvious from reading John Cook's top article. Gray's other major assertion that is in complete contradiction with the evidence is his insistence that global warming is the result of internal variation in the ocean circulations. One may as well point out the other rather unfortunate habit of Gray which is to use ludicrous strawmen and other fallacious "arguments" with which to attack the straightforward science. So he is wont to state, for example, that hoary chestnut of contrived ignorance that climate models are no good because they can't predict the weather two weeks ahead [***]! Gray is either being incredibly ignorant of the science or mendacious...take your pick. [***]http://www.washingtonpost.com/wp-dyn/content/article/2006/05/23/AR2006052301305_pf.html Putting aside Gray, the issue is reasonably clear, even if this is an area of climate science, and the consequences of man-made global warming, that are not very well-defined as yet. The following seems pretty straightforward: (i) everyone seems to agree (Gray, included) that recent years (last couple/few decades) has seen enhanced activity of hurricanes and tropical storms in terms of intensities (Goldenberg et al, 2001; Emanual, 2005; Hoyos et al, 2006; Curry et al, 2006; Elsner et al, 2008). (ii) everyone seems to agree that the enhanced intensity of tropical storms and hurricanes is related to the enhanced sea surface temperatures (SST) that have been directly measured. In fact it was William Gray that first established a causal link between hurrican intensity and SST way back in 1968. (iii) it seems pretty well established that enhanced SST during the period of enhanced high category hurricanes is largely the result of the global warming measured during this period (Barnett, 2005; Trenberth and Shea, 2006; Elsner, 2006). If the Earth warms, the SST warms, and it is the thermal energy in the surface waters of the sea that provide the destructive power of tropical storms. Barnett, T. P. et al (2005) Penetration of human-induced warming into the world's oceans Science, 309, 284–287. Elsner JB (2006) Evidence in support of the climate change - Atlantic hurricane hypothesis Geophysical Research Letters 33 L16705 Elsner, JB et al (2008) The increasing intensity of the strongest tropical cyclones. Nature 455, 92-95 (see link in John Cook's top article). Emanual K (2005) Increasing destructiveness of tropical cyclones over the last 30 years Nature 436, 696-688 (link in John Cook's top article). S. B. Goldenberg, C. W. Landsea, A. M. Mestas-Nuñez, W. M. Gray (2001) The Recent Increase in Atlantic Hurricane Activity: Causes and Implications Science 293, 474 - 479 C. D. Hoyos et al. (2006) Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity Science 312 94 - 97. K. E. Trenberth and D. J. Shea (2006) Atlantic hurricanes and natural variability in 2005 Geophysical Research Letters, VOL. 33, L12704 etc. etc. --------------------------------------------------- here's some of the abstracts of papers cited above: C. D. Hoyos et al. (2006)Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity Science 312 94 - 97. Abstract: "To better understand the change in global hurricane intensity since 1970, we examined the joint distribution of hurricane intensity with variables identified in the literature as contributing to the intensification of hurricanes. We used a methodology based on information theory, isolating the trend from the shorter-term natural modes of variability. The results show that the trend of increasing numbers of category 4 and 5 hurricanes for the period 1970–2004 is directly linked to the trend in sea-surface temperature; other aspects of the tropical environment, although they influence shorter-term variations in hurricane intensity, do not contribute substantially to the observed global trend." Barnett, T. P. et al (2005) Penetration of human-induced warming into the world's oceans Science, 309, 284–287. Abstract: "A warming signal has penetrated into the world's oceans over the past 40 years. The signal is complex, with a vertical structure that varies widely by ocean; it cannot be explained by natural internal climate variability or solar and volcanic forcing, but is well simulated by two anthropogenically forced climate models. We conclude that it is of human origin, a conclusion robust to observational sampling and model differences. Changes in advection combine with surface forcing to give the overall warming pattern. The implications of this study suggest that society needs to seriously consider model predictions of future climate change." **K. E. Trenberth and D. J. Shea (2006) Atlantic hurricanes and natural variability in 2005 Geophysical Research Letters, VOL. 33, L12704 Abstract: "The 2005 North Atlantic hurricane season (1 June to 30 November) was the most active on record by several measures, surpassing the very active season of 2004 and causing an unprecedented level of damage. Sea surface temperatures (SSTs) in the tropical North Atlantic (TNA) region critical for hurricanes (10° to 20°N) were at record high levels in the extended summer (June to October) of 2005 at 0.9°C above the 1901–70 normal and were a major reason for the record hurricane season. Changes in TNA SSTs are associated with a pattern of natural variation known as the Atlantic Multi-decadal Oscillation (AMO). However, previous AMO indices are conflated with linear trends and a revised AMO index accounts for between 0 and 0.1°C of the 2005 SST anomaly. About 0.45°C of the SST anomaly is common to global SST and is thus linked to global warming and, based on regression, about 0.2°C stemmed from after-effects of the 2004–05 El Niño." Elsner JB (2006) Evidence in support of the climate change - Atlantic hurricane hypothesis Geophysical Research Letters 33 L16705 Abstract: "The power of Atlantic tropical cyclones is rising rather dramatically and the increase is correlated with an increase in the late summer/early fall sea surface temperature over the North Atlantic. A debate concerns the nature of these increases with some studies attributing them to a natural climate fluctuation, known as the Atlantic Multidecadal Oscillation (AMO), and others suggesting climate change related to anthropogenic increases in radiative forcing from greenhouse-gases. Here tests for causality using the global mean near-surface air temperature (GT) and Atlantic sea surface temperature (SST) records during the Atlantic hurricane season are applied. Results show that GT is useful in predicting Atlantic SST, but not the other way around. Thus GT "causes" SST providing additional evidence in support of the climate change hypothesis. Results have serious implications for life and property throughout the Caribbean, Mexico, and portions of the United States."
131060. Quietman at 15:46 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Also, the bottleneck actually was a split resulting in two bottlenecks. Two seperate groups were evolving independent of each other in different parts of Africa. The resultant diversity and mixing occured when these groups were reunited 70K years ago and emerged from Africa. Our species emerged 40K years ago (displacing Neandertal) but apparently mixing with earlier departures of H. erectus along the way. This is still contested and unresolved as H. heidelbergensis and H. georgicus are still feeding fuel to this fire.
131061. Quietman at 15:26 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        PS - It's NASA that claims CO2 induced AGW is only 2% of GHG warming. I don't know how they arrived at that number.
131062. Quietman at 15:13 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Patrick From the article: Sloshing Inside Earth Changes Protective Magnetic Field By Jeremy Hsu, Staff Writer 18 August 2008 "A new model uses satellite data from the past nine years to show how sudden fluid motions within the Earth’s core can alter the magnetic envelope around our planet." Read that slowly ["sudden fluid motions within the Earth’s core"] This is not talking about millions of years, or thousands or even hundreds of years. This word "sudden" is very relavent to my argumant.
131063. Quietman at 15:01 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Patrick I was aware of these ocean and mantle conditions. It is not what I am talking about, and although the mantle is currently exposed directly to the south Atlantic it is irrelevant, according to the measurements it's thick and not any warmer than other parts of the seafloor. I am talking about gravitational tides in the magma ie. the Earths heat engine. Heat escapes to the oceans along tectonic plate edges and fissures. And if you study the paleodata there are more plate edges and fissures than recently thought. And then you need to add the extra gravitational forces from jupiter and full alignments. If they can affect the sun they can certainly effect the Earth. Many people don't know that Antarctica as well as North America sits on more than one plate. People talk about a Pacific plate but that should be plural as there are several plates of different sizes, and moving in different directions. Obviously since the plates are irregular this movement changes the amount of thermal energy delivered constantly. But the greatest heat transfer occurs in regular cycles at subduction zones and that is the interesting part. What besides tidal forces can cause these cyclic events? And remember, these forces are not the moon alone although it is the most important because of proximity. PS - I found a couple of references for my earlier statement on extinction: Climate Change Spurred Human Evolution By Andrea Thompson, LiveScience Staff Writer 06 September 2007 Megadrought Put the Squeeze on Our Ancestors By Ann Gibbons ScienceNOW Daily News 10 October 2007 Ancient drought ‘changed history’ By Roland Pease BBC science unit, San Francisco, 12/7/2005 This was from 150,000 to 70,000 years ago. Starting 70,000 years ago, the climate turned wetter.
131064. Patrick 027 at 14:40 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        wustite is FeO, so I'm guessing magnesiowustite is (Mg,Fe)O. The pyrolite model of mantle composition can be given, for purposes of chemical accounting, in terms of weight percents of individual metal (or other) oxides - it would be more convenient to also have it in molar percents but I don't have the time right now to do that calculation, so in weight percents (Karato, p.4): SiO2 45.4 MgO 36.6 FeO 8.1 Al2O3 4.6 CaO 3.7 other oxides 1.4 --- Okay, so the overall geothermal heat release tends to stay near constant over short time periods - but there are short-term fluctuations because some heat release is in the form of individual plumes of magma, which gradually move upward in the crust, some fueling eruptions... this overall process still takes quite a bit of time but the overall heat transport by plumes could, I suppose, be a little bumpy in time. While tidal dissipation contributes just a little to heating, and not much at all within the crust or mantle, this doesn't address the potential for a role in affecting the transport of other heat. (It takes a lot of heat to heat up a corner of a pool, much less energy to swirl the water around). I suppose tidal stresses could alter the timing of volcanic eruptions and earthquakes. But (aside from butterfly-effects, which for the solid and deep Earth would take a very long time to materialize as different configurations of mantle or even core convection, and wouldn't affect much the 'climate' of that convection) I really don't see how it would affect any time-averaged rate of such things - the earthquakes and volcanic eruptions (and geysers, etc.) will happen anyway because of the accumulation of forces and materials driven by geological forces - tidal forces just come and reverse and reverse again, there is no accumulation - On the other hand, as airplane mechanics well know, materials that are repetitively cycled through small stresses can fail eventually from a much smaller stress than would have otherwise been necessary - in some materials, the cycled stresses have to pass some minimum amplitude for this to happen - but for aluminum, this is not the case. So over time, one could imagine repetivive tidal distortions, over hundreds of millions to billions of cycles, might 'weaken' the crust - at least the upper part which is more brittle (the lower part might 'heal it's wounds' because of the warmth ...?)... but the seismic shaking from episodic earthquakes would also do that. How big are tidal stresses in the crust, anyway? seismic waves have wavelengths that, I presume, are quite a bit shorter than the radius of the earth, whereas tidal deformation is distributed on that length scale, which reduces the stress it could cause. And you only get two cycles of tidal stress a day, at most - how many thousands or millions of years would it take for this to be a factor in the mechanical properties of the crust, if ever? - (which implies a short term change in tides couldn't have an immediate impact).
131065. Patrick 027 at 14:02 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Just to be clear, then, my point about tidal deformation vs convective deformation of the outer core - not only is the outer core convective fluid velocity greater, the convection is heterogeneous motion with much variation within the core and continual motion, whereas the tidal deformation's motion only varies from one extreme velocity to the opposite extreme velocity over the whole diameter of the core, so the deformation is that much smaller, and it reverses itself cyclically. The outer core's convective motions will expend much more energy than tidal motion within the outer core to distort the magnetic field lines and even to move against viscous dissipation. --- Mantle crystal structure- if I understand Fig. 1-7 on p.21 of Karato correctly: For the 'pyrolite' model of mantle composition: At the top, mantle material would be over half (by volume) olivine ( (Mg,Fe)2SiO4 - the (Mg,Fe) notation indicates that the composition can vary - in the case of olivine, there is complete solid solubility between the two extremes, Mg2SiO4 and Fe2SiO4), with the remainder orthopyroxene, clinopyroxene, and garnet. Going down, some pyroxene is transformed into garnet at a gradually increasing rate. At ~ 400 km depth, all the olivine transforms to 'Beta (Mg,Fe)2SiO4'. Then with increasing depth, eventually all pyroxene goes into the garnet phase, and a small portion of the 'Beta' does as well. Somewhere at or just below 500 km depth, all remaining 'Beta' is transformed to a spinel crystal structure that isn't Beta. Going deeper, Garnet starts going into Ca-perovskite, the amount of Ca-perovskite gradually increasing; meanwhile, near 600 km depth, garnet also starts going into an 'ILM' phase, which increases gradually until a depth of 650 km. At 650 km, all 'ILM' and a majority of the spinel go into Mg-perovskite, and the rest of the spinel phase goes into Magnesio-wustite (double dots above the u in 'wustite'). Below that, the amounts of both Ca-perovskite and Mg-perovskite increase gradually from the garnet until all garnet has been converted, which occurs somewhere below 700 km. From p.19, the 'beta spinel' is also called wadsleyite, or modified spinel, and the spinel below 500 km is called ringwoodite.
131066. Patrick 027 at 13:07 PM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Another website (actually it's a Google book free preview or something like that): “Numerical Models of Oceans and Oceanic Processes By Lakshmi H. Kantha, Carol Anne Clayson” see p.446,447,451... notes I took from that: Kantha’s global model: TW dissipated by each component: total 3.75 M2 2.57 S2 0.41 N2 0.12 K2 0.03 K1 0.38 O1 0.19 P1 0.04 Q1 0.01 Total energy (PE+KE) of ocean tides about 13 times larger than equilibrium (heavily damped and resonant??) Power input into ocean distributed over area (with some patterns); dissipation concentrated in shallow seas -- (M2 is the lunar semidiurnal (twice-daily) tide. I assume S2 is the solar semidiurnal tide. The tidal response is complicated from the geometry of ocean basins, the coriolis effect, etc, but what I know about the equilibrium tide - the full tide is semidiurnal if it is due to a mass permanently in the equatorial plane; the semidiurnal tide, if it reached equilibrium, would be strongest at the equator and zero at the poles; because the moon and sun are usually somewhat removed from the equatorial plane, they also produce diurnal tides - if they reached equilibrium, they would be strongest at midlatitudes, and zero at the equator and poles, and the high tide in each hemisphere (North and South) would occur at the opposite time of day. (Of course, if the tidal deformation ever actually reached equilibrium, you'd need satellites or some other instrument to ever notice it, because the land and ocean would be rising and falling together.) ------ For a given tide-generating mass at a given distance, the equilibrium tidal bulge height is proportional to the mass of the tide-generator, and to the inverse cube of the distance to that mass, to the fourth power of the radius of the body experiencing the tides divided by the mass of that body (or more generally, the mass contained within that radius). The tidal acceleration is proportional to the mass of the tide generator, the inverse cube of the distance to that mass; it is linearly proportional to the radius of the body experiencing the tides (or more generally, the distance to the center of that body), and is independent of the mass experiencing the tides. Gravitational acceleration g is proportional to M divided by the square of radius r; within the Earth's mantle, g is nearly constant, hence ... to make a long story short, the equilibrium tidal displacement of the mantle/core boundary is about 0.30 times that of the surface. The equilibrium tidal range at the surface due to the moon is ~ 0.54 m (my calculation from math and physics) or 0.56 m according to the physics book mentioned earlier in the Chandler wobble discussion. Some notes from the Karato book mentioned earlier: Total heat flux from the core: estimated from ~ 3 to 10 TW. Energy needed to drive the geodynamo (in terms of thermal energy or mechanical energy? - not sure): roughly 0.1 to 1 TW. Because the outer core is convecting, the total heat flux from the core must be greater than that which would be conducted through material at the adiabatic lapse rate (about 0.7 K/km for the outer core) (remember this is liquid metal alloy, thermal conductivity ~ 40 W/(K m), about 10 times that of surface rocks). The estimated conducted heat from the core ~ 4 TW. (This conducted heat would be unavailable to drive the geodynamo. However, the process of forming the inner core, in addition to giving off latent heat, concentrates some (likely) buoyant impurities, which will then rise - this buoyancy from compositional heterogeneity cannot conduct very fast, and so could drive some convection itself). Cooling of the core by 100 K every billion years would release 5.7 TW of heat (I'm assuming that includes latent heat from solid core growth. The reason for the solid core growing from below is that the melting point rises with pressure, as the solid phase is denser than the liquid phase. The same is true of the mantle - if the mantle were gradually heated up, one of the first parts to melt would be the near the top. In fact it is partial melting upon ascent (even as it cools adiabatically from decompression) that produces the crust and lithosphere (according to Karato, upon some partial melting, dissolved water is lost from what becomes the lithosphere - making the lithosphere more rigid - so the asthenosphere (below the lithosphere) is softer not because it is partially molten but because it has not undergone sufficient partial melting to liberate water (in addition to being warmer, of course). Because the mantle is not a pure substance, it doesn't have a single melting point, and melting and freezing involve chemical differentiation - more generally, this concept helps explain the variations in igneous rocks.) The scale of fluid velocity of the outer core has been estimated at around 0.1 mm per second (thats FAST for a deep geophysical process!). That's about 8.6 m per day! Compare that to the motion required to catch up to tidal deformation. Based on an ideal heat engine, the conversion of the heat driving the outer core convection to mechanical energy is ~ 26.8 % or 28 % efficient, based on top and bottom temperatures of 4100 K and 5500 K, and of 3600 K and 5000 K, respectively - that's based on all the heat going in at the bottom, however, which won't be true, although much of it may be (from latent heating). So of the heat that goes into driving the convection, perhaps between 70 % and 85 % (halving the efficiency to approximate the effect of internal heat sources only) would then go on to the mantle. Of course, some of the mechanical energy goes back into heat anyway, and some goes into electromagnetic energy, but some of that may go back into heat within the core (but I'm thinking it would go back into heat always at lower temperature (higher up within the core) than where it went into mechanical energy, so that entropy increases), ... etc. The mantle and crust have there own heat sources (aside from the heat liberated upon cooling, this is where most radioactivity is - radioactive elements increase in concentration from the core to the mantle, to oceanic crust, to continental crust). I think the total geothermal heat flux at the surface is somewhere around 40 TW. Much of that is conducted through the crust (or for heat generated within the crust, conducted through part of the crust) in the final part of it's journey. If a typical thermal conductivity of crustal material were 2 W/(K m) and the thermal gradient in that material were ~ 30 K/km, that's a heat flux per unit area of ~ 0.06 W/m2 - if that's typical, that's a large fraction of the total heat flux at the surface. Although concentrated in geologically active areas, much of the heat leaving the Earth from below the surface comes through geologically quiet regions of the Earth's crust.
131067. Patrick 027 at 11:44 AM on 22 September 2008
        Volcanoes emit more CO2 than humans
        We as a species are responsible for ~ 100 ppm of the ~380 ppm of CO2 in the atmosphere and some similar amount (in terms of total amount, not concentration) in the ocean. We could easily get it to 400, 450, 500, 550, 600, 700, 800, 1000, ... ppm if we 'wanted to'. We are also responsible for the CH4 increase from ~ 700 ppb to ~ 1700 or 1800 ppb. "Your TSI table" ... "that is a long gradual process and has not much to do with the current situation." Yes. "The extinction I was referring to was during out split in Africa before we were fully human and only numbered in the thousands during a period of severe climate change. But rather than extinction it resulted in increased genetic diversity. " A bottleneck in the population should always reduce genetic diversity; that's not to say that genetic diversity might not increase faster than otherwise depending on the aftermath... What I have heard about the Toba eruption is that humans would have numbered ~ 10,000 or something like that in the aftermath. However, I think Homo sapiens sapiens were on the scene already, although Neanderthals (technically also Homo sapiens, but not Homo sapiens sapiens - if I have my names right) were still around. "My point is that the reason our planet is so active is gravitational stresses. Tidal stress from the moon plays the largest role. But when compounded by gravitational stress from other solar bodies we see cycles occur." My understanding is that most of the tidal energy dissipation occurs in the ocean and some fraction of that helps (along with wind-driven motions) mix the ocean so that it is less stratified than it otherwise would be. From: Oceanography: tides by Dr J Floor Anthoni 2000 http://www.seafriends.org.nz/oceano/tides.htm Total tidal energy dissipation rate: 3.75 +/- 0.08 TW; Of that, most - 3.5 TW - is dissipated in the ocean. The area of the Earth is about 510 trillion m2, so 3.75 TW is a global average of about 0.0074 W/m2; that's roughly a tenth of the geothermal heat flux from the surface. There will of course be some pulsation in the tidal dissipation, but the average over half a lunar month won't change as much, and the average over a year, over 18 years, etc. will vary considerably less. And less than a tenth of that would be dissipated within the solid Earth, core, and atmosphere. (maybe more on that later*) "What would happen to Earth if the moon was only half as massive? http://www.sciam.com/article.cfm?id=half-mass-moon (this approximately gives the same rate of lunar orbit growth given in the 'seafriends' website.) MORE: __________ Tides and ocean: Significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data G. D. Egbert and R. D. Ray (a lot of handy numbers there) "OCEAN SCIENCE: Enhanced: Internal Tides and Ocean Mixing Chris Garrett" http://www.sciencemag.org/cgi/content/summary/301/5641/1858 http://www.aviso.oceanobs.com/en/applications/ocean... ----- http://oceanworld.tamu.edu/resources/ocng_textbook/contents.html http://oceanworld.tamu.edu/resources/ocng_textbook/chapter17/chapter17_04.htm http://oceanworld.tamu.edu/resources/ocng_textbook/chapter17/chapter17_05.htm --- "Tides dissipate 3.75 ± 0.08 TW of power (Kantha, 1998), of which 3.5T W are dissipated in the ocean, and much smaller amounts in the atmosphere and solid Earth. The dissipation increases the length of day by about 2.07 milliseconds per century, it causes the semimajor axis of moon's orbit to increase by 3.86cm/yr, and it mixes water masses in the ocean." --- "The calculations of dissipation from Topex/Poseidon observations of tides are remarkably close to estimates from lunar-laser ranging, astronomical observations, and ancient eclipse records. Our knowledge of the tides is now sufficiently good that we can begin to use the information to study mixing in the ocean. Remember, mixing drives the abyssal circulation in the ocean as discussed in §13.2 (Munk and Wunsch, 1998). Who would have thought that an understanding of the influence of the ocean on climate would require accurate knowledge of tides?" Here's section 13.2: ----- __________ Tides, wind and ocean: 50 Years of Ocean Discovery: National Science Foundation, 1950-2000 ----- For some reason I didn't copy the website for this one, but I must have it saved somewhere in my 'favorites', but anyway: "Modelling global and local tidal dissipation rates E. Schrama": "Oceanic tides are a wave phenomenon set in motion by the gravitational work of Sun and Moon. Traditional geodetic and astronomic techniques allow one to assess the global rate of energy dissipation. Satellite altimetry brings this problem one step further, now making it possible to locally estimate the rate of conversion of barotropic tides into internal tides that initiate deep oceanic mixing." "The global dissipation budget strongly suggests that most of the energy in the tides is lost in the ocean;": 2.4 TW lost in ocean from semidiurnal lunar tide M2 0.1 TW for M2 solid Earth tide 0.2 TW atmospheric dissipation for S2 "Our results confirm that": M2 wave dissipates 2.42 TW, of that: approx 1.7 TW dissipated in coastal seas by friction; 0.7 dissipated in deep oceans "Suggested in literature is internal wave generation and the relevance is that this process is responsible for mixing between lighter surface waters and the deeper ocean. The hypothesis by W. Munk to explain the oceanic density stratification is that about 2 TW is required for maintaining this balance, Egbert and Ray were the first to suggest that about half of this amount could come from tidal mixing, the remaining part could come from wind induced mixing." ----- http://www.agu.org/meetings/wp06/wp06-sessions/wp06_OS15B.html __________ Wind and ocean "The Work Done by the Wind on the Oceanic General Circulation Carl Wunsch" http://ams.allenpress.com/perlserv/?request=get-abstract&issn=1520-0485&volume=28&page=2332 "Improved global maps and 54-year history of wind-work on ocean inertial motions Matthew H. Alford" http://opd.apl.washington.edu/scistaff/bios/alford/assets/Alford2003.pdf http://opd.apl.washington.edu/scistaff/bios/alford/alfordglobalmap.html OTHER undifferentiated: http://www.aviso.oceanobs.com/fileadmin/documents/kiosque/... http://www.jamstec.go.jp/esc/publication/annual/annual2006/... http://www.sciencedirect.com/science?_ob=ArticleURL...
131068. Quietman at 05:00 AM on 22 September 2008
        Volcanoes emit more CO2 than humans
        PS The wobble I refer to is long term geographic polar wobble and not orbital. As I do not know the cyclic rates of planetary alignments compared to this wobble I don't know if there is a connection or not. I was simply pointing out that there is a cyclic climate shift involved in the wobble.
131069. Quietman at 04:54 AM on 22 September 2008
        Volcanoes emit more CO2 than humans
        Patrick Re: 27.5 The extinction I was referring to was during out split in Africa before we were fully human and only numbered in the thousands during a period of severe climate change. But rather than extinction it resulted in increased genetic diversity. But that aside: I have no argument with your explanations. My point is that the reason our planet is so active is gravitational stresses. Tidal stress from the moon plays the largest role. But when compounded by gravitational stress from other solar bodies we see cycles occur. This is where the Fairbridge hypothesis comes into play. His hypothesis predicts sunspot activity (or lack thereof) with apparent accuracy. But sunspots are symtomatic. It is the cause of the sunspots I believe that is also the cause of the current heat imbalance. Your TSI table bears witness to the 5 million year positive slope that I was referring to in other posts on this site. But that is a long gradual process and has not much to do with the current situation. As we as a species are responsible for 2% of the increased CO2 (per NASA) I can not see any way that it can be pertinant to GW. In fact, I don't see GW at all, but I do see northern polar warming and increased equatorial temperatures which only makes sense if ocean driven (tectonic caused) oscillations are at fault.
131070. chris at 22:11 PM on 21 September 2008
        Do cosmic rays cause clouds?
        Re #37 Mizimi There is a very good reason for making the obvious distinction between "weather" and "climate". It's not true to say that "weather is the end product of the process climate...". Weather is the day to day variation in the parameters of temperature, pecipitation volume and type, wind speed and direction, atmospheric pressure and so on, within a particular climate regime. And so there isn't any particular feedback from weather into climate. This could only happen if there were persistent trends in the weather. However if that were the case it wouldn't be "weather" but "climate"! No one is dismissing the idea that the CRF may influence cloud formation and that this might have an influence on weather/climate. There just isn't any particularly compelling evidence for this outwith some effects on weather. It's unfortunate that the purveyors of this notion have done so in a manner that borders on the fraudulent and is at least very sloppy science. It's gratifying that at least one of these (Jan Veizer) has chosen to address this issue with scientific rigour in recent years. And we have plenty of HARD data on the subject. We have been monitoring the CRF in exquisite detail for at least the last 50 years. The huge imbalance in the Earth's enenrgy budget that has given us very marked warming, especially in the last 30-odd years, has occurred during a period in which the CRF has been essentially flat (outwith the solar cycle variation), if anything trending in a slight cooling direction. If we are interested in addressing the problems relating to recent and contemporary global warming, we should consider what we know to be the case [massive enhancement of the Earth's greenhouse effect results in a shift of the Earth's global temperature towards a new (higher) equilibrium temperature], rather than hang onto dubious notions that we know categorically have made no contribution to the warming.
131071. chris at 21:39 PM on 21 September 2008
        Can animals and plants adapt to global warming?
        Re #23 Mizimi In speaking of evolution you state: ["The process has no ethics, no morals, no compassion, empathy or any other attitude we as humans bring to bear on the issues."] Happily, however, we as humans DO have ethics, morals, compassion and empathy, as well as the less emotional abilities to reason, and make valid interpretations about our relationship with the natural world and our impacts, as well as being able to address what we consider to be in the best interests of ourselves and our near, and not so near, descendants. There's no question that the natural world will recover from any large scale trashing of existing environments, either mechanical (habitat destruction/pollution) or via man-made rapid global warming. The question is what sort of a world we wish to live in and leave to those that follow us. Happily (again!) there are very many intelligent and well-informed individuals and organizations both public and corporate who are taking a clear-headed and rational approach to these very real problems. There aren't too many that hold the ludicrous and repellent "argument" that it's all "natural" and that evolutionary processes will "pick up the pieces" in some far-off future. I suspect the vast majority of individuals are rather more concerned with making mature policy decisions that relate to the next several decades and few hundreds of years, rather than to wash their hands of the issue knowing that several hundreds of thousands and millions of years from now, that a trashed natural environment will have likely recovered.
131072. chris at 21:11 PM on 21 September 2008
        Can animals and plants adapt to global warming?
        Re #25 HealthySkeptic re your comment: ["The Carboniferous and the Ordovician are the only periods in the earth's history when global temperatures were as low as they are today. The late Ordovician was also an Ice Age, while at the same time CO2 concentrations were nearly 12 times higher than they are today (~4400 ppm). According to greenhouse theory, the earth should have been exceedingly hot. Obviously, other factors besides atmospheric CO2 have larger impacts on the earth's temperature and global warming."] That's not really correct. One needs to be careful to ensure that the paleoproxies for CO2 and the proxies for cold spells (generally evidence for widespread glaciations) are matched in time. The Carboniferous cold spells cover a massive period (20 million years and close to 70 million years if one extends this through the cold spells of the late Carboniferous and Permian). There are many proxy measures of atmospheric CO2 levels that match these time periods. In other words we know pretty well that the cold periods of the Carboniferous (and Permian) are associated with low atmospheric CO2 levels. The same unfortunately isn't the case for the very brief late Ordovician cold spell. This "only" lasted a couple of million years, and there isn't so far a proxy CO2 measure that overlaps the cold spell, so we don't know what the atmospheric CO2 levels were. Remember also that the solar constant was around 4% lower than now and so the threshold for cold spells leading to glaciations during this period is considered to be around 3000 ppm of atmospheric CO2 (rather than around 500 ppm of atmospheric CO2 now). Until we have proxy CO2 measures that we know are "contemporaneous" with the late Ordovician cold spell, we simply don't know whether there is an apparent mismatch between the temperature and greenhouse gas levels. Notice that the Earth has had many globally cool spells right through late Phanerozoic (several in the Jurassic, Cretaceous and Paleogene and of course in the Neogene). Where there are "contemporaneous" measures of atmospheric CO2 the cool spells match the periods of low greenhouse gas levels rather well (and vice versa - hot/warm spells match high atmospheric greenhouse gas proxy measures). This data has recently been compiled in a review: D. L. Royer (2006) "CO2-forced climate thresholds during the Phanerozoic" Geochim. Cosmochim. Acta 70, 5665-5675". see also: R.E. Carne, J.M. Eiler, J. Veizer et al (2007) "Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era" Nature 449, 198-202
131073. Patrick 027 at 11:12 AM on 21 September 2008
        Volcanoes emit more CO2 than humans
        Back to 4. for a moment: ... "At first glance (could be wrong?) it would also make sense to expect faster mountain building and thus an enhanced erosion rate (with some time lag) -" ... Of course, mountain building is not quite as continuous and ongoing a process as sea-floor spreading. Faster sea floor spreading (or a greater total length of mid-ocean ridges) and continental rifting will tend to raise sea level (assuming the wider mid-ocean ridges result from faster sea-floor spreading), as will erosion of continents with sediment transfered to continental shelves, etc, while continental collisions and associated mountain and plateau building will of course tend to lower sea level, while individual continents may be raised or lowered for other reasons. That can affect global average temperature by changing the albedo - this depends on cloud cover and vegetation, though.
131074. Patrick 027 at 10:44 AM on 21 September 2008
        Volcanoes emit more CO2 than humans
        ... Actually the climate forcing due to a 1% change in solar TSI would be closer to 2.4 W/m2. And while solar TSI may often go up and down by 0.1% or something like that, a change of 1% would be more likely over ~ 100 million years, associated with the long-term solar brightenning over it's stellar lifespan. (A formula for solar TSI as a fraction of the present day value is 1/(1 - 0.38*t/4.55), where t is the number of billions of years from now, negative for in the past. This is an approximation that may be innaccurate for near the beginning or end of the solar lifespan - I got it from a paper by James Kasting, forgot which paper. From this formula, solar TSI as a percent of present day solar TSI: 75.0 % at 4 Ga (billion years ago) 80.0 % at 3 Ga 82.7 % at 2.5 Ga 85.7 % at 2 Ga 88.9 % at 1.5 Ga 92.3 % at 1 Ga 93.0 % at 900 million years ago (Ma) 93.7 % at 800 Ma 94.5 % at 700 Ma 95.2 % at 600 Ma 96.0 % at 500 Ma 96.8 % at 400 Ma 97.6 % at 300 Ma 98.0 % at 250 Ma (~Paleozoic/Mesozoic boundary) 98.4 % at 200 Ma 99.2 % at 100 Ma 99.6 % at 50 Ma ... and in the future: 104.4 % in 500 million years 109.1 % in 1 billion years 120.1 % in 2 billion years ---------- And 'wobbles' in mantle convection and continental drift - these wobbles are analogous to day-to-day weather changes in the atmosphere; it is mantle weather. The weather reshapes itself in (depending on the weather features in question - I'm thinking of midlatitude synoptic-scale features) days as the winds reshape the pressure variations (depending in part on temperature variations) that shape the winds. In the mantle, momentum (and therefore the coriolis effect) is negligible; pressure gradients (due to density variations) drive motion against friction. The density variations that force the motion cannot change much faster than the motion itself - thermal diffusion being a much slower process. So large rapid changes in mantle convection and continental drift don't happen. But over many millions of years, the mantle and lithospheric weather will change; as cold slabs of material descend down from subduction zones, continents collide, and material is no longer fed to the descending slab, while the remaining slab continues descent; as continents overide midoceanic ridges; as heat builds up within the mantle near the core or perhaps around pieces of recycled crust to produce buoyant plumes, and as heat builds up under supercontinents, and as continents rift apart and sink a bit. Continents individually are warped and tilted, rise, and sink, as the move over density variations in the underlying mantle (a slow process). Over a long time, one might define a mantle climate. One kind of mantle climate change could then be the transition from layered convection to whole mantle convection. Whole mantle convection is simply convection cells with updrafts and downdrafts extending from top to bottom. In layered convection, the mantle would convect in two seperate layers (boundary at about 660 km depth from surface). When there is a boundary to convection (the top of the mantle, the bottom of the mantle, the bottom of the outer core, and possibly at 660 km depth in the mantle), heat must be transported by conduction to the next layer, which requires a higher thermal gradient, so heat can build up in the lower layer relative to the upper layer. Why would there be two layers of convection? As pressure increases with depth, material is compressed; this is associated with an adiabatic lapse rate where temperature rises or falls within a mass without the conduction of heat. But in solids there can also be phase transitions (I've also heard of different liquid phases of the same substance but ...). As with the phase transitions of melting/freezing and evaporation/condensation, a solid phase transition may involve a change in heat as well as density. Obviously as pressure increases, phase transitions to higher-density phases are favored. If a phase transition gives off latent heat (like condensing of water vapor to form clouds), than that transition will occur 'sooner' at lower temperature - more specifically, the Clapeyron slope dp/dT = change in entropy / change in volume, where dp is the change in pressure of an equilibrium phase transformation with a change in temperature dT. There are multiple phase transitions within the mantle from about 410 to about 660 km from the surface. The Clapeyron slope of the 660 km phase transition (which, going down, involves a change of much of the mantle's material to a perovskite crystal structure) 660 km is a nominal position used for identification - the actual position varies) is negative, which means that at higher temperature, the phase transition occurs at lower pressure. Without phase transitions and in the absence of significant coriolis effect, warmer material at a given pressure will generally rise and colder material will sink due to the effect of temperature on density. But as warmer or colder material rises or sinks across the 660 km phase transition, the actual position will rise or fall, respectively, due to the temperature change, and this produces a density variation that is opposite that caused by the temperature variation, and if strong enough, will produce a force that prevents convection across the boundary. From what I have read (not much, really), I've gotten the impression that there is some layered convection and some whole mantle convection at present; earlier in Earth's history, there may have been mainly just two-layered convection, and perhaps changing conditions caused a transition toward some whole mantle convection around the time of the Archean-Proterozoic transition (?)... Why would that happen? - well, material properties change with changing temperature; as the mantle as a whole cools, the 660 km transition should gradually rise upward overall - in the future, if it goes far enough, it would catch up with other phase transitions (which, if they have positive Clapeyron slopes, would be moving downward - where they meet I would expect a new phase transition to occure with an intermediate Clapeyron slope) ... not all of the mantle substance actually goes into the perovskite structure, ... the overall viscosity increases over time with decreasing temperature overall ... layered convection would allow heat buildup in the lower mantle relative to the upper mantle, so perhaps the temperature difference could have become so great that eventually it overcame the impediment to whole-mantle convection ? - if that's how it works, then one would expect episodic whole mantle convection, after each episode of which, the temperature change with depth would be reduced and so one would go back to two-layer convection - but I'm not sure that's how it would have worked - anyway, the advent of whole mantle convection could then have increased the cooling of the core, which would affect inner core growth rate (ps that liberates latent as well as buoyant composition variations, which help drive outer core convection, which of coarse powers the magnetic field), and this could also affect the geochemistry of the layers and the crust (?)... BUT also so far I have been describing phase transformations as being at equilibrium, but particularly in colder material, it isn't so easy for atoms to rearrange themselves, so phase transformations can be delayed beyond equilibrium, and the resulting microstructure that results when the phase transformation finally occurs can affect the viscosity (and/or rigidity?) of the material, and this would apply to the behavior of cold descending slabs coming from subduction zones. The rate of subduction affects the temperature of the slab, which affects the position and result of phase transformation, the effect on rigidity, and that could affect whether or not the descending slab penetrates into the lower mantle or comes to rest on the 660 km boundary ... SEE Karato, "The Dynamic Structure of the Deep Earth" --- 5. "We almost went extinct once already" Would you be refering to the supereruption of Toba about 75,000 years ago? While it did occur as an ice age was starting or setting in or growing stronger, a supereruption's effects would be particularly sudden, and eventually would have subsided into the background as Milankovitch forcing went on - of course there would be some climatic inertia from any buildup of snow/ice during the cooling from the supereruption. A supereruption, as with single eruptions and earthquakes, etc, are episodic events, and takent one at a time, not necessarily indicative of any overall trend in continental drift, mantle convection, or geothermal heat fluxes.
131075. chris at 10:39 AM on 21 September 2008
        Arctic sea ice melt - natural or man-made?
        Re #223 Mizimi This doesn't make any sense: ["In any event, melting sea ice = drop in ocean temp - more biomass (plankton like it cool) = more sequestration of CO2 and so we go round again. The system as a whole has numerous ways to address imbalances as it has (successfully)in the past."] No...and one can't make up fanciful, simplistic and physically-unviable ladybird book notions as explanations of real world phenomena. Global warming results in WARMING of the oceans AND MELTING of land ice (mountain glacial and ice sheet ice). If you think that warming-induced melting of land ice results in ocean cooling and more biomass and sequestration of CO2, then you are sorely deluded (or just haven't bothered to think properly). Have a think about what processes occurred during the last glacial to interglacial transition as a result of enhanced absorption of solar energy due to Milankovitch cycles, for example. You'll find that the massive amounts of land ice melt (enough to raise sea levels by over 100 metres) during the last glacial to (our present) interglacial transition, 20,000-8000 years ago was accompanied by a warming of the oceans. Let's not pretend that we don't know what we do know. Notice that the "system" doesn't really "have numerous ways to address imbalances". The "system" responds to imbalances in the global heat budget (e.g. by changes in direct solar insolation or enhanced greenhouse gas concentrations) by settling towards a new equilibrium temperature. We can see this very clearly by addressing what has happened in the past. That's the problem. There's no evidence that the Earth has any particular "self-regulating" properties outwith the massive thermal intertial provided by the oceans. So as solar insolation (Milankovitch-induced) or greenhouse gas concentrations increases, so does the Earth's temperature.
131076. chris at 07:42 AM on 21 September 2008
        Arctic sea ice melt - natural or man-made?
        Re #240 Mizimi As Philippe has already indicated, you've posted links to a series of either non-science "sources", or have misinterpreted the science sources you've sourced. For example, on the effects of greenhouse gas emissions on plant growth and CO2 sequestration by the terrestrial environment, it's very clear that the massively enhanced CO2 emissions, especially during the last 30-odd years have decidedly NOT seen enhanced terrestrial absorption via enhanced plant growth as any sort of mitigation of our massive CO2 emissions. The reasons are very clear, and one of them is indicated in the very article you linked to: (i) There is a straightforward limit to the extent to which enhanced CO2 results in enhanced CO2 sequestration, as a result of many factors (e.g. nutrient and water availibility in the real world). As author of the "co2 effect on trees" article you linked to, states: "However, the scientists who conducted the study said such high growth rates probably will not be sustained as the experiment continues. They emphasized that the results do not indicate that more lush plant growth would soak up much of the extra CO2 entering the atmosphere from fossil fuel burning." (ii) In fact rather that the terrestrial environment, by far the main "sink" for atmospheric CO2 sequestration is the oceans. However, these are increasingly less efficient in absorbing enhanced atmospheric CO2 as CO2 levels rise, first because the ocean surface tends to saturate as atmospheric CO2 concentrations rise (Le Chatalier's principle), and secondly because, as the oceans warm, they become less effective sinks for CO2 (since warm water absorbs less dissolved CO2 than cold water). (iii) Third. because as the world warms, CO2 sequestration by the terrestrial environment actually tends to decrease. This has been shown, for example, in a paper published last week in Nature: "Prolonged suppression of ecosystem carbon dioxide uptake after an anomalously warm year" John A. Arnone et al (2008) Nature 455, 383-386. Abstract: "Terrestrial ecosystems control carbon dioxide fluxes to and from the atmosphere1, 2 through photosynthesis and respiration, a balance between net primary productivity and heterotrophic respiration, that determines whether an ecosystem is sequestering carbon or releasing it to the atmosphere. Global1, 3, 4, 5 and site-specific6 data sets have demonstrated that climate and climate variability influence biogeochemical processes that determine net ecosystem carbon dioxide exchange (NEE) at multiple timescales. Experimental data necessary to quantify impacts of a single climate variable, such as temperature anomalies, on NEE and carbon sequestration of ecosystems at interannual timescales have been lacking. This derives from an inability of field studies to avoid the confounding effects of natural intra-annual and interannual variability in temperature and precipitation. Here we present results from a four-year study using replicate 12,000-kg intact tallgrass prairie monoliths located in four 184-m3 enclosed lysimeters7. We exposed 6 of 12 monoliths to an anomalously warm year in the second year of the study8 and continuously quantified rates of ecosystem processes, including NEE. We find that warming decreases NEE in both the extreme year and the following year by inducing drought that suppresses net primary productivity in the extreme year and by stimulating heterotrophic respiration of soil biota in the subsequent year. Our data indicate that two years are required for NEE in the previously warmed experimental ecosystems to recover to levels measured in the control ecosystems. This time lag caused net ecosystem carbon sequestration in previously warmed ecosystems to be decreased threefold over the study period, compared with control ecosystems. Our findings suggest that more frequent anomalously warm years9, a possible consequence of increasing anthropogenic carbon dioxide levels10, may lead to a sustained decrease in carbon dioxide uptake by terrestrial ecosystems." (iv) And of course we can cast aside "wishful thinking" notions of enhanced plant sequestration as a mitigation of our massive greenhouse gas emissions, by the simple expedient of observing the atmospheric CO2 concentratrions. If these were being reduced by plant sequestration, one might expect greenhouse gas levels to be tailing off or decreasing. In fact they're INCREASING at a rather rapid rate (faster than linear, much in line with our emissions).
131077. chris at 07:04 AM on 21 September 2008
        Arctic sea ice melt - natural or man-made?
        I forgot to post the url for the Ramanathan article in press in PNAS (see post #249) It's: http://www.pnas.org/content/early/2008/09/16/0803838105.abstract
131078. chris at 06:32 AM on 21 September 2008
        Arctic sea ice melt - natural or man-made?
        One of the possible contributions to Actic warming was raised by leebert (posts # 29,34,37,42,47,49,58). This is so-called "black carbon" (part of the man-made aerosol load from burning "dirty fuels"), of which leebert referred to work by Ramanathan who has published extensively on this subject. The human-induced aerosol load from human emissions results in a combination of cooling and warming [black carbon on ice reduces albedo and promotes melting of ice; aerosols in the atmosphere screen the solar irradiation ("global dimming"] which counters greenhouse-gas-induced warming. In fact Ramanathan has shown that the overall effect of man-made aerosols is to counter the effects of global warming resulting from man-made enhancement of the Earth's greenhouse effect (see my posts # 33,39,41,45,48,53,66). Ramanathan has just published a detailed account of the committed effect of our greenhouse gas emissions, once the "cooling" effect of atmospheric aerosols is gradually overcome. It's not an encouraging scenario. It's pertinent that the very author that leebert has used to downplay the role of greenhouse gas emissions on global warming and Arctic sea ice attenuation, is actually one of the most vociferous scientists publishing on the extreme dangeroers of the committed warming that will result from our already-released greenhouse gas emissions. here's the abstract of the paper about to be published in the Proceedings of the National Academy of Sciences: On avoiding dangerous anthropogenic interference with the climate system: Formidable challenges ahead V. Ramanathan and Y. Feng Abstract "The observed increase in the concentration of greenhouse gases (GHGs) since the preindustrial era has most likely committed the world to a warming of 2.4°C (1.4°C to 4.3°C) above the preindustrial surface temperatures. The committed warming is inferred from the most recent Intergovernmental Panel on Climate Change (IPCC) estimates of the greenhouse forcing and climate sensitivity. The estimated warming of 2.4°C is the equilibrium warming above preindustrial temperatures that the world will observe even if GHG concentrations are held fixed at their 2005 concentration levels but without any other anthropogenic forcing such as the cooling effect of aerosols. The range of 1.4°C to 4.3°C in the committed warming overlaps and surpasses the currently perceived threshold range of 1°C to 3°C for dangerous anthropogenic interference with many of the climate-tipping elements such as the summer arctic sea ice, Himalayan–Tibetan glaciers, and the Greenland Ice Sheet. IPCC models suggest that ≈25% (0.6°C) of the committed warming has been realized as of now. About 90% or more of the rest of the committed warming of 1.6°C will unfold during the 21st century, determined by the rate of the unmasking of the aerosol cooling effect by air pollution abatement laws and by the rate of release of the GHGs-forcing stored in the oceans. The accompanying sea-level rise can continue for more than several centuries. Lastly, even the most aggressive CO2 mitigation steps as envisioned now can only limit further additions to the committed warming, but not reduce the already committed GHGs warming of 2.4°C."
131079. Patrick 027 at 04:16 AM on 21 September 2008
        Volcanoes emit more CO2 than humans
        "No more than the normal "wobble" "..."For supporting evidence for actions of oscillations you can check the threads on this site. "..."it's the vulcanism driving the drift" I think we're talking about 3 or 4 distinct phenomena now. By normal wobble, do you mean Milankovitch cycles or the Chandler wobble or...? 1. Milankovitch cycles: ~100,000 yr eccentricity; ~40,000 yr (obliquity) and ~20,000 yr (precession) cycles that involve changing orientation of the Earth's axis. However, the importance to climate being the change in the axial tilt relative to the orbit around the sun; the body of the Earth itself stays aligned with it's axis the same way - the geographic north pole is still in the Arctic ocean the whole time, etc. Causes of the Milankovitch cycles: gravitational effects of other planets, solar and lunar tidal torques on the Earth's equatorial bulge (The precession cycle, a wobble of the direction of the Earth's tilt relative to it's orbit about the sun, is actually due to a combination of changing direction of tilt and a changing orientation of the semimajor axis of the Earth's orbit). (The equatorial bulge is due to the centrifugal force of rotation - the geopotential surfaces of the Earth, such as sea level, are distorted in such a way that the gravity due to mass and centrifugal force from rotation, as vectors, add to produce an effective gravitational vector locally perpendicular to the surface so that there is no local 'sideways gravity'. PS equilibrium tidal bulges can also be computed by setting 'sideways gravity' to zero. Tidal dissipation of the Earth's rotation and transfer of angular momentum to the moon's orbit result in changes in lunar tidal forces and the Earth's equatorial bulge over time (many millions of years), both affecting the obliquity and precession cycles.) 2. Chandler Wobble and True Polar Wander. As vector quantities, a spinning object has a rotation w which is parallel to the axis of rotation, and an angular momentum L. L is parallel to w if the object is symmetrical about the spin axis - specifically if the spin axis is aligned with a principle axis. (Angular momentum is equal to the rotation times the moment of inertia; but the full moment of inertial is actually a tensor quantity (written as a 3 by 3 matrix) - but if the coordinate axes are chosen to align with the principle axes of the body, 6 of the 9 components are reduced to zero, leaving three moments of inertia, each about a principle axis, so that the component of rotion along each such axis can be multiplied by the corresponding component of moment of inertia to get the component of angular momentum along that axis.) So if the rotation w is aligned with a principle axis, the angular momentum L is also aligned with w and the same principle axis. If there are no external torques applied and the body is not being deformed, there is no wobble. If the three moments of inertia are equal (such as for a perfect homogeneous sphere or a sphere with only spherically-symmetric density variations centered on the center of the sphere), L and w are always parallel. But when the body has different moments of inertia (such as due to an equatorial bulge), then L and w can be in different directions. Without external torques, L must be constant in an inertial reference frame (that does not rotate with the body); but w may shift around; in the reference frame of the body itself, I think both can shift around - the changes over time are described by the Euler Equations. In what can be called the "Tennis Racket Theorem", if w is shifted from a principle axis by a small amount, then: A. if L and w are near one of the 'extreme' principle axes - with the larges or smallest of the three moments of inertia, then L and w oscillate about that axis (specifically I think L traces out a circle about the principle axis though I'm not sure offhand), and so rotation about such an axis is stable. B. But if L and w are initially near the intermediate principle axis, L and w move away from that axis and so rotation about that axis is unstable. The Chandler wobble is a shift of Earth's rotation axis about the principle axis of the Earth most nearly parallel to the rotation axis (this is an extreme principle axis - it has the largest moment of inertia due to the equatorial bulge - the other two principle axes are in (or almost in) the equatorial plane). The spin of the Earth is perturbed by small amounts from the principle axis by earthquakes and seasonal mass distributions, but rotation about this axis is stable. (And over time, some kind of viscous dissipation would actually tend to return the rotation axis to alignment with the principle axis - for fixed L in an inertial reference fram, such alignment minimizes the square of |w| and thus minimizes the rotational energy; on Earth, the spin axis is never found more than ~ 10 meters** (much less than climatologically insignificant) from the principle axis at the Earth's surface, and the period of the Chandler wobble is ~ 440 days** - this specific info is found on p. 261 of Classical Mechanics: A Modern Perspective. Second Edition. Vernon Barger and Martin Olsson. 1995. **Caution - most info is fairly correct but I have found a few specific numbers in that book which were wildly off - the mass of Venus on p.396, and I think the rate of tidal damping and the rate of lunar orbital change by tidal damping were also off.) 3. The two moments of inertia about the principle axes in or near the equatorial plane are about equal. However, if a supercontinent persisted in mid-to-high latitudes for a time and heat built up in the mantle beneath (continental crust is of course thicker but also has more radiactive heating per unit volume than oceanic crust, both of which have more than the mantle) so that the supercontinent were elevated, conceivably if this were extreme enough (I'm not sure how far this would have to go or how likely it is it could ever get that far, especially in the distant past when the equatorial bulge would have been larger), the principle axes could be shifted out of alignment from the spin axis enough and maybe the principle axis nearest the spin axis would become an intermediate axis (? or maybe that part's not necessary) and then the rotation becomes unstable ?? - or maybe it doesn't become unstable ?? - but the end result is that the supercontinent ends up at low latitudes so once again the principle axis with the largest moment of inertia is close to the spin axis. This process shifts the whole body of the Earth around; this is true polar wander. PS if this ever happenned - conceivably it might happen (that's the impression I have as of yet) faster than it takes for the equatorial bulge to deform back to equilibrium, which means parts of the equatorial bulge could be shifted into higher latitudes - the ocean would of course respond much faster, so parts of the mid-to-high latitudes could have 'land' made of exposed oceanic crust (which could result in much release of CH4 from hydrates/clathrates) while parts of the equatorial ocean would be extremely deep. But it depends on how fast or slow the different processes occur relative to each other. The only hypothesized instances of true polar wander on Earth that I know of would be in the late Neoproterozoic, and I don't know what the state of the evidence is for it. 4. And of course over time there is continental drift as the plates grow at rifts or ridges and go back into the mantle at subduction zones. Faster plate movements should tend to correspond to greater geothermal heat transport to the surface, wider mid-ocean ridges and thus higher sea levels (although I read something recently...), and faster geologic CO2 emission. At first glance (could be wrong?) it would also make sense to expect faster mountain building and thus an enhanced erosion rate (with some time lag) - which itself would at least partly counteract the tendency for a warmer climate to sustain an equilibrium elevated CO2 level by causing faster geologic sequestration of CO2 to balance the faster CO2 release. At first glance it also would make sense to expect more frequent eruptions of all or many kinds, including those explosive low-latitude eruptions that have a short-term cooling effect - but collectively over time this would have a persistent cooling effect, but CO2 builds up over time and eventually would have the larger effect on long-term climate. The size of the plates would also have an effect - smaller plates would require a longer total length of plate margins, which could correspond in part to a longer length of mid-ocean ridges, etc. Globally the average geothermal heat loss is ~ 0.1 W/m2; even if it could have been doubled ~ 100 million years ago or whenever, that would still only be ~ 0.2 W/m2. It's a small climatological forcing and it doesn't change very fast; in contrast, doubling CO2 is a forcing of about ~4 W/m2; a 1% increase in solar TSI would be a forcing of about 3 W/m2. Have to take a break now...
131080. Quietman at 00:57 AM on 20 September 2008
        Arctic sea ice melt - natural or man-made?
        Philippe I have to agree there. Last year was quite unusual and without the freak weather and would likely not have melted as much as this year. It does remain to be seen.
131081. Quietman at 00:46 AM on 20 September 2008
        Volcanoes emit more CO2 than humans
        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.
131082. Quietman at 00:43 AM on 20 September 2008
        Volcanoes emit more CO2 than humans
        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.
131083. Philippe Chantreau at 18:00 PM on 19 September 2008
        Arctic sea ice melt - natural or man-made?
        I don'tknow what predictions you are referring to, you're still not linking anything. The real experts were actually quite close to the mark. After all that thread on ice, you still can't look up NSIDC. You'll find all you need to know there. BTW, the answer is, they don't really know. It shows indications that the minimum has happened but only time will tell for sure.
131084. Mizimi at 06:22 AM on 19 September 2008
        What does CO2 lagging temperature mean?
        "Science does the best work possible with the best data that is available. Data are constantly sought, improved and correlated. Science is always a work in progress." I absolutely agree. And part of the process of improvement is to be open to valid critisism ( in the proper sense)and honest where data is sketchy or non-existent. Unfortunately for the scientists involved in this particular model, (I believe)it was high-jacked for other purposes and hence the current polarisation. Consequently resource which could be usefully addressing those 'iffy' areas are squandered on sawing sawdust.
131085. Wondering Aloud at 06:18 AM on 19 September 2008
        Arctic sea ice melt - natural or man-made?
        Yes check for yourself... not just at that one spot. For tree ring proxies used in the famed hockey stick and elsewhere cherry picked might be too kind. Many of them may not even be good proxies for temperature at all. An average of selected doubtful proxies does not make for a reliable record. If you can find how they chose which proxies to use and which to exclude, and why, you will find interesting reading. We have digressed a long way. How about all of those predictions of the Arctic ice disappearing this summer? How well did they make out now that the minimum is past? Remember how the young ice from last winter was going to melt much easier and all that stuff?
131086. Mizimi at 06:02 AM on 19 September 2008
        Satellites show no warming in the troposphere
        Have just graphed CO2 and GMT records from 1978 to 2007. By using the year on year change in CO2 plotted against GMT yearly change you get a remarkable match... I then factored the CO2 to get the 1998 peaks to align and then ALMOST ALL the peaks/troughs from 1978 onwards line up. Unfortunately can't find a way to put the graph on here! But you can always do it yourself ( unless someone tells me how to post it)
131087. Mizimi at 01:32 AM on 19 September 2008
        Satellites show no warming in the troposphere
        Looking at a graph generated from the Global data column it appears to trundle along with more or less equal + and - shifts until 1998 when there is a large rise of around +0.5C which declines to zero (2000) From then on there is a further large rise peaking in 2005 at +0.3C and then falling back to +0.1C From 1998 on the graph seems to include two events which have pushed the GMT well above mean. The CO2 record shows a ggod correlation to GMT fluctuations AND a spike in 1998 and subsequent spikes at the 'right' places...but the scale effect is wrong. 1998 shows +0.5C when the CO2 rise was 1.0ppm (97-98) Later CO2 increases of the same magnitude are not matched by similar Temp rises. It seems some other factors are at work..??
131088. Quietman at 23:49 PM on 18 September 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Thanks for the PNAS link, that is an interesting paper. But please note the last statement just above their conclusion.
131089. Mizimi at 23:30 PM on 18 September 2008
        It warmed before 1940 when CO2 was low
        One point to consider: oil and gas as fuels did not come into widespread use until the mid 1950's and began to supplant coal from 1960 onwards. Coal was the major fuel before 1940 and emission controls virtually non-existant, so there would also have been a cooling effect from aerosols to (partially) balance GG emissions.
131090. Philippe Chantreau at 15:09 PM on 18 September 2008
        Arctic sea ice melt - natural or man-made?
        A few cherry picked proxies? That's your description. For those who'd rather check for themselves, the latest reconstruction is here: http://www.pnas.org/content/early/2008/09/02/0805721105.full.pdf+html All data, methods, and computer code are also available online.
131091. Patrick 027 at 10:11 AM on 18 September 2008
        Volcanoes emit more CO2 than humans
        "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.
131092. Quietman at 08:27 AM on 18 September 2008
        Temp record is unreliable
        theTree Yes it does have an effect, producing a false feedback through CO2 release which is a GHG. The argument on CO2 is climate sensitivity. Hansen claims a high sensitivity while Spencer claims a low one. The results thus far indicate Spencer is scientifically but not politically correct.
131093. Quietman at 08:21 AM on 18 September 2008
        Svensmark and Friis-Christensen rebut Lockwood's solar paper
        Mizimi Nothing should be tossed, just put into perspective, the same goes for CO2.
131094. Quietman at 08:14 AM on 18 September 2008
        Volcanoes emit more CO2 than humans
        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.
131095. Quietman at 08:10 AM on 18 September 2008
        Volcanoes emit more CO2 than humans
        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.
131096. Quietman at 08:05 AM on 18 September 2008
        Arctic sea ice melt - natural or man-made?
        WA I agree, botanic references in the historic records alone implicate a much warmer climate *in the locations where they were written) at that time. It proves that parts of the earth currently cold were warmer then but it does not prove it was a global phenomena. It was likely a situation more like today where we see climate shifts. I don't know what astronomy says but I am interested in knowing if it was truely a global phenomena (the current is not global as can be proven by looking at local climate histories that have remained stable).
131097. Wondering Aloud at 06:48 AM on 18 September 2008
        Arctic sea ice melt - natural or man-made?
        Well I don't know I have seen a lot of things from astronomy papers to medieval records that strongly support a warmer middle ages. Cherry picked proxy studies showing otherwise do not convince. I have no idea about Soon or various others and I don't much like OISM. However for scientific method you might want to be careful. Robinson is best known as a whistle blower on scientific method. Linus Pauling made similar charges against him and rather famously lost the ensuing law suit along with the money for his Nobel prize.
131098. Quietman at 06:41 AM on 18 September 2008
        The link between hurricanes and global warming
        Philippe Re: "all the RC contributers" No, just one, but it made me loose all respect for the site. There are plenty of other sites with pro-AGW authors that I can and do respect (like this one).
131099. Quietman at 06:29 AM on 18 September 2008
        It's the sun
        PS In other words Camp & Tung demonstrate that the recent additional warming is not from TSI, with which I can agree.
131100. Quietman at 06:24 AM on 18 September 2008
        Solar cycles cause global warming
        Camp & Tung assume the IPCC's accepted sensitivity is accurate. If we take their numbers and lower the sensitivity to Spencer's numbers we get a very different result. Their study is on the solar forcing, the feedback is assumed.

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