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Venus Unveiled

Filed under: — raypierre @ 16 March 2008

Something over a week ago I had the pleasure of making my way up to the little ski resort of La Thuile in the Val D’Aosta to learn about the latest results from the Venus Express mission. (You can imagine it was a tough decision to go to La Thuile and hear real scientists talking about Venus when I could have instead been listening to luminaries such as Mark Morano drone on at the Heartland Institute pseudoscience bash. ) My own connection with the Venus Express meeting came about through some work I’ve been doing on habitability of the newly discovered "Super Earth" extrasolar planets like Gliese 581c. Many of us think these may be "super-Venuses" rather than "Super-Earths," so it seemed like time to touch base with the people working on our own Venus. The fact that we can put together the same bits of physics we use to understand global warming on Earth in order to understand the interplay of the carbon dioxide greenhouse with sulfuric acid clouds on Venus is a testament to the fundamental power of climate science, and gives the lie to Claude Allègre’s oft stated claim that there is no such thing as a science of climate. Altogether, it was a thrilling meeting.

The Venus Express mission was described in this earlier RealClimate article, and you can read more about the mission at the VEX home page. Venus Express was done on the cheap, mostly using instruments cobbled together from leftover hardware from Mars Express and the Rosetta comet mission. The results have been nonetheless spectacular, and La Thuile provided a suitably spectacular venue in which to discuss them. This meeting was one in the series of Rencontres de Moriond in which scientists get together for a week of intensive discussion of leading-edge topics in physics — plus equally intensive skiing, climbing, hiking and enjoyment of good Northern Italian cooking. If you’ve ever read any of Jeremy Bernstein’s accounts of how he got involved in mountaineering through his attendence at particle physics meetings conducted in similar circumstances, you’ll know the general idea about how such things work. It’s a great way to shake loose creative thinking. And it’s one of those things that makes real science so much fun. Perfectly aside from the setting, it was a thrill to see the vigor of this field, and the influx of talented new young postdocs and graduates students, with all their fresh ideas and enthusiasm. I hope to give just a bit of the flavor of what went on during that eventful week.

A Field Guide to Venus

Venus has an Earthlike mass and surface gravity, the latter being 8.9 meters per second per second, only slightly less than Earth’s. Venus is in a very nearly circular orbit about the Sun with orbital period (year) equal to 224.65 Earth days. Venus rotates much more slowly than Earth, however, and this has many consequences for the atmospheric dynamics, since it greatly reduces the Coriolis accelerations that do so much to organize Earth’s large scale atmospheric circulations. In fact, the rotation of the planet is retrograde — i.e. opposite in direction to the rotation of the orbit. The siderial day on Venus — the period with which the star patterns would repeat, if you could see the stars from the surface — is 243 Earth days, but since this is in the retrograde direction, it adds to the angular velocity of the planet relative to the Sun. Thus, the rate of rotation relative to the Sun is 1/224.65 + 1/243 rotations per Earth day, leading to a solar day of 1/(1/224.65 + 1/243), or 116.7 Earth days. This is the time between sunrises, as would be seen from the planet’s surface. Thus, Venus’ solar day is roughly half of its year, as illustrated in the sketch below (credit K. Fuller).

You might think that the long day would result in the dayside heating to extreme temperatures while the darkness-plunged nightside plummeted to relatively frigid values. In fact, because of the dense 92 bar atmosphere, it takes a very long time for most of the atmosphere to heat up or cool down, and there is little day/night variation over most of the depth of the atmosphere. Higher up, however, there is a diurnal and seasonal cycle, as illustrated by the black vs. green lines in the accompanying sketch — Venus Express in fact found indications that the diurnal cycle extended deeper into the atmosphere than this traditional sketch suggests, with significant temperature variations penetrating to 45 km. altitude. The atmosphere of Venus is nearly pure carbon dioxide, with a few percent of nitrogen thrown in. It also contains traces of water vapor, which though tiny, contribute significantly to the greenhouse effect of the atmosphere.Most of the greenhouse effect comes from the carbon dioxide, however, which by itself is sufficient to raise the surface temperature most of the way toward its observed value of around 470C. A key feature of the atmosphere of Venus is the sulfuric acid cloud deck. These clouds account for the high reflectivity of Venus, but because they also reflect infrared back to the surface (unlike water clouds, which absorb and emit), they have a warming effect as well, and constitute the second most important factor in the greenhouse effect of Venus after carbon dioxide. Radiation model calculations demonstrate that the clouds have a pronounced net cooling effect on the planet, when both factors are taken into account. The cloud deck comes from combinations of sulfur dioxide with water, but the nature of the sulfur cycle allowing the cloud deck to be maintained is currently a matter of considerable uncertainty.

The VEX instruments

For a full list of the complement of instruments on Venus Express you can take a look at the VEX Instrument Summary .For the most part, I’ll focus on data from VIRTIS and SPICAV-SOIR. VIRTIS is a spectral imager which observes patches of Venus in a set of wavelengths ranging from the ultraviolet (0.25 microns) to the near infrared (5 microns). On the night-side VIRTIS infrared yields thermal emission, which can provide information about cloud structure and temperature, as well as information about atmospheric constituents.. On the day-side VIRTIS infrared images are dominated by reflection of the near-infrared component of sunlight; the absorption of solar near-infrared also provides valuable information about atmospheric constituents, as well as information about cloud structure that is complementary to the night-side thermal emission. SPICAV/SOIR is a spectrometer with somewhat different characteristics; it returns high-resolution ultraviolet images , which reveal interesting aspects of atmospheric dynamics. The reflection of short wavelengths like ultraviolet gives a good indication of the occurrence of cloud particles, but the utility of ultraviolet observations is enhanced by the presence of an as-yet unidentified ultraviolet absorber in the atmosphere of Venus, which shows up in the form of dark streaks on ultraviolet images. Besides being useful as an ultraviolet imager, SPICAV/SOIR is used with a technique called occultation, in which the attenuation of starlight or sunlight passing through the atmosphere provides information about the vertical profile of various atmospheric constitutents, including sulfur dioxide, water vapor (and its various isotopes), carbon monoxide, carbonyl sulfide and oxygen. SPICAV is derived from spare parts from a similar instrument (SPICAM) that flew on Mars Express, but SOIR, which adds infrared channels useful for solar occultuation measurements, was newly developed for Venus Express.

Venus Express also carried a thermal infrared spectrometer, PFS, which was intended to study wavelengths longer than 5 microns. Thermal emission in these wavelengths is important to the understanding of the radiation budget of Venus. Unfortunately, this instrument was the one disappointment in an otherwise spectacularly successful mission, as the PFS was rendered inoperative by the failure of a critical shutter to open. But no worries — the instruments that did work provide a great wealth of new material to think about.

Venus Express sports a lightweight radio-science package, VeRa. Radio occultation is a low tech but highly valuable workhorse of planetary observation. By observing the refraction of radio waves passing through the atmosphere, one can obtain density profiles, since the index of refraction is proportional to density. From density and the hydrostatic relation (i.e. pressure is the weight of all the fluid above you) it is possible to reconstruct temperature profiles if you know what the atmosphere is made of. On Venus, radio occultation can observe the atmosphere down to about 45 km. altitude from the surface.

Venus: A dynamic atmosphere

Venus is not the featureless cue-ball you’d think it is from low-resolution observations in the visible spectrum. Observations of Venus in the infrared and ultraviolet spectrum show a variety of intriguing wave and vortex patterns. The highly dynamic nature of the upper atmosphere of Venus is not a new discovery, but the increasingly sophisticated observations have continued to enrich our understanding of Venus atmospheric dynamics. Indeed a new era of Venus meteorology is dawning. For multiple reasons, the deep atmosphere of Venus is a fairly quiescent place: the low rotation rate of Venus makes it easy for the dense atmosphere to transport heat and keep temperatures horizontally uniform, while the mass of the atmosphere and the limititation of infrared cooling by the dense carbon dioxide atmosphere even out the diurnal and seasonal cycle. Moreover, through a combination of reflection, scattering and absorption, only a trickle of sunlight reaches the surface to drive convection and other atmospheric circulations. Things can happen more rapidly in the upper part of the atmosphere, which can also support stronger temperature gradients. Keep in mind that the top 1% of the mass of the atmosphere of Venus is about like the whole atmosphere of Earth, and that there is plenty of dynamics and temperature variations at least down to the 2 bar level (about 45 km above the surface). There is plenty of active atmosphere to keep dynamicists happy. If you will, you can think of Venus as consisting of a dynamically active 2 bar "atmosphere" atop a sluggish deep "ocean."

Now let’s take a look at some of the circulation patterns revealed by Venus Express. The patterns are made visible through the modulation of the cloud distributions, and for the most part reflect motions taking place at altitudes of 45-60 km. In the night-side infrared, clouds show up as dark patches or streaks, since they block upwelling infrared; relatively cloud-free areas are bright. The image at the right shows the night-side VIRTIS infrared image, taken looking toward the South Pole, on the right half of the image. The left half is a day-side observation in the visible spectrum, from reflected sunlight. You can see a concentrated vortex structure near the pole, and an intriguing spiral cloud pattern, probably due to the differential rotation of the atmosphere — i.e. the fact that it is swirling like a bathtub vortex and not in rigid-body rotation. It is generally believed that there is subsiding motion near the pole, but the extent of vertical motions associated with these cloud patterns is not well known. Some of the patterns are interpreted as variations in cloud top height (hence temperature) induced by the vertical motion field, rather than as variations in cloud thickness. Many of the eddies give an appearance very much like two-dimensional vortices having little vertical motion, while other cloud and wave patterns look more like Earth’s boundary layer convective cloud streets (modulated by wind shear), or like gravity waves.

The South Polar vortex shows a dipole pattern very much like has been seen earlier at the North Pole. Here’s an example of the evolution, viewed by VIRTIS in an infrared channel thought to be mostly responding to cloud top height (see ‘South-polar features on Venus similar to those near the north pole’ by G. Piccioni et al. Nature,29 November 2007.) The vortex you are seeing is about 2000 km. across.

And this color image of the vortex, taken in the 5 micron band, shows the dipole structure more clearly. The bright yellow region is the dayside.

Although the surface of Venus rotates only slowly, the upper atmosphere has taken on a rotation rate of its own, and air around the 50km level circles the planet with a period of roughly 5 days. This is called super-rotation, because the rotation is in the same sense as the rotation of the planet, but stronger. It allows the upper atmosphere to support substantial temperature gradients, by providing a Coriolis acceleration which can offset pressure gradients associated with temperature variations. The super-rotation is not actually a rigid-body rotation, but has a very distinctive profile in latitude. Venus Express has provided new observations of the zonal wind pattern using cloud-tracking methods, an example of which is shown to the right. Note particularly the uniform velocity in the nightside winds, extending from 70S to the Equator; the polar regions are in something closer to rigid body rotation. What accounts for this pattern? In all theories, the transport of momentum by transient eddies is critical to redistributing the angular momentum and creating low-latitude super-rotation. Thus, the improved understanding of eddy dynamics from Venus Express will help us to determine the character of the eddies and their transports. An essential question remains to be answered: What are these eddies and where to they come from? Much prevailing thinking ascribes the eddies to instabilities of horizontally sheared jets — the barotropic instability — but the images themselves do not give a very clear impression of jet instability.

In a related notable result, the modelling team from the Laboratoire de Meteorologie Dynamique, Paris has achieved a very convincing simulation of super-rotation in a new Venus general circulation model. Though the deep atmosphere of Venus is sluggish, its dynamics is nonetheless crucial since it is this circulation which brings angular momentum from the surface to the upper atmosphere; this circulation is also critical for atmospheric chemistry, since it transports gases to the surface where they can react to form minerals, and (more speculatively) transports volcanic outgassing to the cloud deck.

Higher in the atmosphere, the extreme temperature difference between the dayside and the nightside, due to solar absorption in the atmosphere on the dayside, drives a circulation flowing from the hot dayside to the cold nightside. This circulation also gives rise to another fascinating phenomenon, the oxygen airglow. On the dayside, extreme ultraviolet from the Sun can actually break up carbon dioxide molecules into their component parts, which liberates free oxygen atoms. These are carried to the cold nightside, where they recombine into O2, releasing energy in the 1.27 micron infrared range. Venus express carried out many new observations of the airglow phenomenon and the circulation in these extreme upper reaches of the atmosphere — which also bear on the processes allowing planetary atmospheres to escape to space.

Venus atmospheric chemistry: The cloud deck

Using occultation methods, Venus Express has shed far more light on atmospheric chemistry than I can begin to go into here, but I will at least mention a few of the results. Quite remarkably, the remote-sensing techniques can detect not only the profiles of water vapor in the atmosphere, but also the various isotopes, notably the heavier version — deuterated water, HDO, in which deuterium substitutes for one of the hydrogens. In the Earth’s upper atmosphere, the HDO to H2O ratio is depleted relative to the water vapor in the lower atmosphere, because the heavier HDO condenses out more readily when it rains. On Venus, the situation is the opposite, and HDO is greatly enriched relative to lower level water vapor. This occurs because water vapor is broken apart by sunlight, and the lighter hydrogen escapes more readily than the heavier deuterium. Venus Express also found, though, that oxygen is escaping from the atmosphere in the ratio expected from breakup of water, suggesting that non-thermal escape processes in which chemical reactions give an extra kick to atoms, are important. Putting together a consistent picture which simultaneously accounts for the oxygen escape and the deuterium enrichment will tell us much about the mechanisms by which planets lose atmospheres, and perhaps shed light on issues affecting habitability of extrasolar planets.

Because the sulfuric acid cloud deck has such a profound impact on the climate of Venus, the chemistry of the Venusian sulfur cycle is of great interest. What is the lifetime of the clouds, absent resupply? Venus Express measurements, and associated laboratory experiments, are helping to clarify these issues as well. Carbonyl Sulfide has been observed in the atmosphere, and there are good indications that the formation of polysulfur (S2, S4, etc.) and possible subsequent precipitation plays a role in the sulfur cycle. The nature of sulfur dioxide resupply connects up with the contentious issue of catastrophic resurfacing of Venus, which I’ll take up shortly.

Peeking at the surface

With such a thick CO2 atmosphere, you’d think it would be utterly impossible to see the surface of Venus in the infrared. The issue of "saturation" of the absorption of infrared by CO2 has been discussed previously on RealClimate, but it turns out that even with 92 bars of CO2 in the atmosphere, Venus is not saturated throughout the infrared spectrum. There is a narrow window region in the vicinity of 1 micron wavelength, which allows the surface to be observed in the infrared. Venus Express has exploited this window to make maps of infrared emission from the surface, which, combined with topography data from the Magellan radar altimiter, allow an estimate of surface emissivity. Hopefully, this will shed some light on the minerology of the surface, which is largely mysterious. Just as a sample of the new data, here is an image showing the surface brightness anomaly overlain with radar topography. This image comes courtesy of Joern Helbert and his student Nils Müller, and of course as for all results derived from VIRTIS, the VIRTIS P.I’s Giuseppe Piccioni and Pierre Drossart deserve a round of applause as well.

One of the most exciting questions concerning the nature of Venus is whether the planet has undergone catastrophic resurfacing in the relatively recent past.. Venus has no plate tectonics to gradually engulf part of the surface. Unlike Earth or Mars, impact craters are uniformly distributed over the surface. By some reckonings, there appear to be no old craters, as witnessed by the apparent lack of craters in a state of partial degradation. This would argue for the entire surface having been engulfed or flooded over with magma some time in the past half billion years or so. However, the morphology of the surface lends itself to varying interpretations, and these were the subject of a genteel debate between David Grinspoon (for resurfacing) and Sue Smrekar (in the opposing camp). I can’t say that anybody struck a knockout blow, but it was certainly informative, and serves as another example of the way real scientists try to hash out uncertainties and conflicting theories. There is no herd mentality here, any more than there is in studies of Earth’s climate. It’s in the DNA of scientists to poke at theories all the time, and never cease their questioning. “Consensus” does not consist in agreeing on everything, but rather in agreeing on a common set of tools and methodologies, as well as on a set of results that can be considered settled to a sufficient degree that further results can be confidently built upon them. Consensus of this sort exists for Venus as well as for Earth, and nobody makes a fuss about it.

The question of resurfacing has major implications for the climate history of Venus. No active volcano has yet been observed on Venus, and it has been conjectured by David Grinspoon that perhaps Venus goes through cycles of extreme volcanism and sulfur resupply to the cloud-deck, followed by long quiescent periods in which the clouds dissipate and leave the planet’s surface much hotter than its already torrid temperature. This is indeed a frontier area of planetary science, and one which engages phenomena extending from the interior to mineral reactions at the planet’s surface, and onward to photochemistry in the outer reaches of the amosphere.

The Earth seen from Venus: A Pale Blue Dot

Modern planetary probes are so versatile they can be re-programmed to do things their original designers never anticipated. With colleagues at the University of Chicago, I’m doing that now, using a minerology probe on the Spirit and Opportunity rovers on Mars to examine atmospheric argon. Taking a leaf from the Pale Blue Dot observations of Earth from Galileo, popularized by Carl Sagan (look. here. for a detailed report of those observations), Venus Express mission scientists have gotten the bright idea of using observations of Earth from Venus to test methods for searching for habitable extrasolar planets. The next generation of extrasolar planet-finders will return spectra of the planets averaged over the entire planetary disk, so learning how to make the most of "single pixel astronomy" is of the utmost importance.

Already, observation of the Earth spectrum by VIRTIS has detected Earth’s CO2, oxygen and water vapor. Observations by SPICAV show the absorption feature characteristic of ozone. Work is underway, spearheaded by Darren Williams, to see if Earth’s oceans can be detected through the characteristic sun glint they produce.

At the meeting I also had the pleasure of meeting Enric Pallé, a young astronomer who is probably best known to regular RealClimate readers for his attempts to estimate trends in Earth’s albedo through ground-based measurements of lunar Earthshine. . Enric’s connection with the Earth from Venus session comes about because he has been looking at ways to measure a planet’s length of day by examining fluctuations in reflected sunlight; he has also been trying to detect Earth’s vegetative "red edge" through Earthshine observations. Enric tells me that he has refined his somewhat controversial Earth albedo estimates, and these no longer show the mysterious and striking long-term albedo trends reported in the original paper. To tell the whole story, though, I should note that the satellite based CERES albedo estimates (which showed an opposite trend to Earthshine) have evidently also been revised, owing to discovery of a drift due to deterioration in a filter. We’ll have to wait for Enric’s paper to see the details, but estimates of albedo fluctuations appear to be converging, according to preliminary results he showed me. This is science at its best, and a reminder both that detecting trends from satellites is difficult, and that one should avoid building elaborate and earthshaking interpretations on data from novel observing techniques like Earthshine until they have time to mature. We all could have been spared a lot of grief if the Alabama boys who pushed their erroneous microwave satellite temperature trends over surface records for so long had been as diligent as Enric in re-examining their methods.

What a week!

All in all, quite a week! And despite the lack of good snow on the cross-country trails, I did manage to get in a few nice excursions up the valley, with the help of a prodigious supply of red klister. I am looking forward to seeing what another year of Venus Express observations brings.

155 Responses to “Venus Unveiled”

  1. 101

    Lowell writes:

    [[How long before increased CO2 results in a runaway greenhouse on Earth like has happened on Venus.]]

    About a billion years.

    [Response: And even then, it won't be rising CO2 that triggers a runaway, but the continued long-term secular increase of solar luminosity. --raypierre]

    [[I’m afraid if we don’t do something about increased CO2 soon, we will end up with something close to Venus]]

    Don’t worry about it. Not going to happen.

    [Response: Actually, if you want to worry about something runaway-like you should worry about what clouds might do on the destabilizing end of the possible spectrum of cloud effects. Clouds have a net cooling effect on Earth's climate at present. If you take away this net cooling effect, then the Earth gets a lot closer to the runaway greenhouse threshold for a saturated atmosphere (though the undersaturation of the atmosphere still helps to preserve a margin of safety). I don't actually think there's much risk of cloud cooling disappearing completely, or going into a runaway, but still this line of thought shows you how much potential clouds have for making things a lot worse than the mid-range IPCC scenarios. --raypierre]

  2. 102
    Jim Galasyn says:

    Thanks to Ray in 98 for the education. News to me!

  3. 103
    Jim Eager says:

    Re Lowell @ 88: “How long before increased CO2 results in a runaway greenhouse on Earth like has happened on Venus.”

    It’s not going to happen, period. Please read the original post and all comments in the thread.

  4. 104
    Hank Roberts says:

    > 88, 89, sunspots
    See the discussion over at
    Solar Cycle /Forums/ Solar Cycle 24/ Solar Activity/ New Sunspot
    See posting by marconis 03/24/2008 — restates the FAQ explaining why
    “These are more likely to be cycle 23 spots.”

  5. 105
    Patrick 027 says:

    Re 99, 101 – I wonder, though – what if plants (perhaps with our super-wise distant descendents’ help) evolved to incorporate titanium dioxide, producing nanoparticles of it in leaves, as a pigment for photosynthesis (realizing that may be hard to do giving the stability of titanium minerals – right? Maybe the plant produces special enzymes in the roots…). With enough UV driven photosynthesis, the plants could over time abandom chlorophyll, and then we’d have bright white vegetation. (of course, then the continents would be much colder than the oceans, so the monsoons wouldn’t work, I’d think… – but where the monsoons fail, the plants migh die and get covered by darker sand, and then the rains might come again?). Of course, in order for that to work, there’d have to be a selective advantage of the white plants over the green plants. A whole field of white plants might do well by staying cool (especially if surrounded by darker plants that can help bring the rains of thermally direct convection), but a single white plant wouldn’t have any obvious advantage – unless … well, that’s probably too off-topic.

    Now, I’m not saying that I’d want to live in that world, or leave that world for my great grandkids or their great great grandkids or their … – but for SO long in the future, who knows? Maybe just easier to put out the space mirror ($4 trillion? but they’d have millions of years to build it. It wouldn’t have to be a single piece – many small mirrors with solar powered steering mechanisms could be mass-produced. They might even be colored to reduce the solar IR while letting in more visible. They could be retasked to push asteroids off of collision courses when necessary)… Maybe just easier to lay out the white tarps and floating white pumice (made from real rock!) rafts.

  6. 106
    Patrick 027 says:

    Re 104 – actually, at least some plants are reflective in the solar IR – Sudan grass comes to mind. As the sun gets brighter – well I know it will eventually expand and become a red giant, but before then, is it already very slowly reddenning and expandind or is it turning more blue or just staying put at it’s current color? That would matter for how best to design plants – reddenning might leave some opportunity to use the IR albedo. If the red and/or blue fluxes are increasing, some color-selective reflection could limit absorption to narrower wavelength bands where photosynthesis is most efficient, leaving the overall appearence a lighter shade of green.

  7. 107
    Chris Colose says:

    Re 96

    Spencer seems to be inferring what he calls “feedback” from variability that is controlled by other things.

  8. 108

    RE #99, Lowell, while this current bout of GHGs & GW will not go into permanent runaway conditions, it could go into what I call limited runaway (from human control), or hysteresis. That is, the warming caused by human emissions could lead to nature emitting more GHGs (e.g., from frozen methane in permafrost and ocean hydrates) and reduced albedo (whiteness of snow & ice), leading to further warming, leading to further conditions that increase warming, and so on until it gets pretty hot — hot enough perhaps to release other monsters, like hydrogen sulfide from anoxic oceans that could kill off a lot of life in the sea and on land. You can read Mark Lynas’s SIX DEGREES to get a better idea of what’s possible in the geological short run (over the next 100,000 years or so).

    OTOH, even if we drastically reduce GHGs and avoid tipping into a situation that will eventually take us up to 6 degrees and serious long-drawn out catastrophe, there are lots of bad things in the pipes right now, which may lead to many people dying and many species going extinct. Disease spread, severe water shortages (due to drought and glacial & snow pack cycle diminishing around the world), crop reductions (due to pests, heat, flood, drought), severe storms, floods, even floods amid droughts. Consideration of even half the damages of this best-case scenario should have been enough to make every person on planet earth start reducing their GHGs way back in 1990. Sad commentary on “humanity.”

  9. 109

    re 96

    Spencer’s presentation of both his 2007 GRL paper and a precis of its forthcoming sequel was about the only fundamental science on offer at the NYC affair, and I look forward to seeing your take on it, and that of others , as Roy has done interesting work in the past, and now has a bona fide modeler on his team.

  10. 110

    #104 Hank, NASA expertise has already declared cycle 24 started,

    its been so long since I’ve observed so many spots, but these ongoing are different than the usual, they are pale, by appearance not so cold. Solar experts may explain…

  11. 111
    Thomas Lee Elifritz says:

    To all you ‘not going to happen’ folks, this post is about Venus. Venus is there for all of you to see. Venus seems to easily refute, in the most glaring manner possible, all of this ‘not going to happen’ rhetoric.

    Not only can it happen in the long term it’s a done deal.

  12. 112
    Jim Eager says:

    Re Thomas Lee Elifritz @ 111: Venus is Venus, Earth is Earth. Taking into account all of the differences between the two at this point in time, it’s not going to happen on any time scale meaningful to humans.

  13. 113

    # 100, & “As a kid I read a science fiction book in which astronauts visited Venus. When they dropped below the cloud deck they discovered that is was a hot tropical world of jungles populated by dinosaurs. I prefer thinking of it that way.”

    I agree with you, Craig; that’s the way I’d like to think of it. And your comments made me think about the real, unspoken point of this topic on Venus, a planet so inhospitable to life that it’s rather poignant. The important lesson from this post is that we have a beautiful, wonderful, life-sustaining planet (in contrast with Venus and other planets). We should cherish it and take care of it.

  14. 114
    bkellysky says:

    NASA says the present sunspots are “old” Cycle 23 spots, and they can occur even after Cycle 24 has started. They have the polarity of Cycle 23 spot, not the reversed polarity of Cycle 24 spots.
    Excerpt from:

  15. 115

    Re 111: To all you ‘not going to happen’ folks, this post is about Venus. Venus is there for all of you to see. Venus seems to easily refute, in the most glaring manner possible, all of this ‘not going to happen’ rhetoric.

    Not only can it happen in the long term it’s a done deal.

    I thought the “worst case scenario”, in terms of runaway, was something closer to the Rain Planet (where they made the clone army) in Star Wars — the ice caps melt, the oceans rise, and then the diurnal temperature swings lead to a never ending collection of daily rain storms as the atmosphere is pumped full of water during the day and it all rains out (over the oceans …) at night when the temperatures drop.

  16. 116
    Chuck Booth says:

    Re # 106 Patrick:
    I’m curious to know why you think Sudan grass reflects solar IR? Can you cite any references on that? It is my understanding that surface color (e.g., red) has no bearing on IR absorption – the only significant reflection of IR is by shiny metallic surfaces. But, I could be wrong on this.

  17. 117
    pete best says:

    Is it true that all the second order feedbacks (output from one process being a input for another) are amplification/positive ones and that no negative/dampening feedbacks exist at this level in the climate system. Humans would have to engineer them in order to mitigate climate change?

  18. 118

    RE #117, & “Is it true that all the second order feedbacks (output from one process being a input for another) are amplification/positive ones and that no negative/dampening feedbacks exist at this level in the climate system. Humans would have to engineer them in order to mitigate climate change?”

    That is the million dollar Q. My thinking is that even in a scenario with positive feedbacks dominating, there would still be some negative ones (which would make the temperature chart jagged rather than strictly increasing and straight or smooth).

    However, we do know that earth has been in such positive feedback dominating scenarios in the past — 55 & 251 mya — though eventually the warming plateaued and came back down with positive cooling feedbacks…after annihilating a big chunk of life on earth.

    So it’s possible we are in the beginnings of one now or could be so within this century or next. It’s not something we’d want to gamble with…though that’s what we’re doing.

  19. 119
    Thomas Lee Elifritz says:

    I thought the “worst case scenario”, in terms of runaway, was something closer to the Rain Planet (where they made the clone army) in Star Wars — the ice caps melt, the oceans rise …

    Ok, so far so good, and then what?

    Ocean carbonates dissolve, methane clathrates are released, and then what?

    Forests die, the Amazon withers, the biosphere collapses and then what?

    Do the arithmetic, it ain’t pretty.

  20. 120
    C. W. Magee says:

    Random hard rock responses to various venus stuff:

    Re: terraforming
    The high surface temperature and low partial pressure of H2O would make hydrating Venus rocks tricky. The CO2 would also complicate things, since alkali-earth hydrous minerals would then carbonate (unless too hot), releasing the water.

    Also the calcite decomp temperature at 92bar CO2 is way higher than the current surface temp, so if that is where Venusian CO2 came from, it must have been much hotter in the past. calcite and anhydrite should be stable on the surface, but there is no evidence that they exist on Venus that I know of- presumably a result of slow kinetics due to no water.

    Zircons require at least some igneous differentiation, for which there is little evidence on Venus’s surface. And if there has been resurfacing, then you would get that age.

    Isn’t there something odd about Venus’s atmospheric Argon? An atmospheric sample return would be way easier than a surface one, and would let the noble gas guys do Kr, Ne, and Xe isotopes.

  21. 121

    Re #118: That is the million dollar Q. My thinking is that even in a scenario with positive feedbacks dominating, there would still be some negative ones (which would make the temperature chart jagged rather than strictly increasing and straight or smooth).

    We’ve never had run-away warming during any of the past large warm periods. The average global temperature has been between 12C and 22C for the past 600 million years or so — and I don’t have a handy graph going back any further. That tells me that there must be some negative feedback that happens near 22C that’s going to prevent any form of “Venus Effect”.

  22. 122
    pete best says:

    RE #118, If it takes 000′s 0f years for earth to come back down to equilibrium then that is not use for humandkind is it?

    I have read around a bit recrntly and found several quotes from people in the know regarding climate change and its consequences.

    Is thi take on climate change possibly true?

  23. 123
    Lawrence Brown says:

    Pale Blue Dot or small(and growing) Black Hole? An article in yesterday’s NY Times by Dennis Overbye suggests that there’s a non zero chance that the new CERN Large Hadron Collider may make global warming( and everything else)moot.

  24. 124

    Lawrence Brown posts:

    [[Pale Blue Dot or small(and growing) Black Hole? An article in yesterday’s NY Times by Dennis Overbye suggests that there’s a non zero chance that the new CERN Large Hadron Collider may make global warming( and everything else)moot.]]

    I doubt they can make a black hole. But even if they could, it would be so small that it would evaporate by Hawking radiation before it did any damage. Colliders have to be superpowerful just to create tiny subatomic particles from collisions between other particles. They ain’t gonna make something big enough to swallow the Earth.

  25. 125
    Ray Ladbury says:

    Lawrence Brown, This whole idea is crap. There is no way they are going to greate a black hole. They’ll be lucky if they even create any Higgs’ bosons (ther reason they built the thing). Black holes result from conditions in the core of supernovae. You won’t produce them terrestrially–ever. I do wish the Times reporters would either get the most tenuous clue about science or just leave it alone.

  26. 126
    Patrick 027 says:

    Re 116 – I saw it on a graph – albedo as a function of wavelength. Although looking at it again, I should qualify the information – it only goes from 400 nm out to 1000 nm (1 micron) – and only ~ 940 nm for some of the surfaces graphed, including Sudan Grass and Straw. On the same graph, the albedo of Alfalfa also rises sharply going into the infrared from visible, although not as much as Sudan Grass. Straw’s albedo increases gradually from blue to around 900 nm and levels off. Snow’s albedo declines going into the infrared but it is still relatively high at 1000 nm.

    See p. 90, in Chapter 4 (The Energy Balance of the Surface), of “Global Physical Climatology” (Hartmann, – I think it was 1994).

  27. 127
    Chuck Booth says:

    Re #126 Patrick,
    Thanks – that is useful info that prompted me to look into it some more. I found additional information on this at

    And in an online preview of the book, Physics of Climate, By José Pinto Peixoto, Abraham H. Oort

  28. 128
    Lawrence Brown says:

    Barton and Ray. Thanks for the reassurance. I realize that there’s a lot of weirdness in physics,like quantum tunneling, Shrodinger’s poor cat that’s neither in a live or dead state until somebody breaks down the wave function(looks in the box?) and Bell’s inequality, but having the LHC being able swallow the Earth or turn it into a shrunken lifeless dwarf called a “strangelet” appears to cross the line even the wild world of quantum physics. Good to know what some mainstream physicists think of this.

  29. 129
    Ray Ladbury says:

    Lawrence Brown, These same two nutjobs filed a similar suit to block operations of the Relativistic Heavy Ion Collider at Brookhaven. The thing is that there are lots of different versions of string theory, and you can fine one or the other of them that will tell you just about anything. It’s just that there’s no reason to believe it.
    Physicists have pretty much always had a macabre sense of humor about such things. The article mentioned that on the Manhattan Project, they’d looked at the possibility of igniting fusion in the water vapor in the air and turning the world to a mini-Sun. Fermi went around before Trinity and took bets on the odds of incinerating the State of New Mexico. When I was a grad student, the question was whether the vacuum was in fact stable or metastable (if there were greater than 22 flavors of quark, it was metastable, but as it turns out, there are 4).
    Look, cosmic rays have energies up to 10^21 eV. Even transforming to the center of mass frame, a 10^21 eV proton colliding with a proton at rest has an energy ~1000 times as high as the CM energy of the LHC! Such events happen a few hundred times a year in Earth’s atmosphere. This one doesn’t even pass the straight-face test.

  30. 130
    David B. Benson says:

    pete best (122) — Yup.

    And thanks for the useful link.

  31. 131

    RE #121 & “We’ve never had run-away warming during any of the past large warm periods.”

    That’s true, we’ve never had permanent runaway warming as on Venus….or else we wouldn’t be here to talk about it.

    However, from a lay perspective on the current situation, enquiring minds might want to know if we are causing the current warming, and is there a point in that human-caused warming at which nature takes over and continues the warming thru positive feedbacks up to some higher temp (as has happened in the past).

    That may not be “runaway” from a non-human-centric, scientific perspective, but it would be a temporary (up to 200,000 years) runaway-from-human-control situation from an anthropocentric perspective, which some scientists have told me is better referred to as HYSTERESIS. But I think the term “runaway” is more informative and useful, as long as we’re clear we are not referring to a permanent situation as on Venus, but only a “runaway-from-human-control” situation (which, of course, would not apply to a prehuman era). And that situation, while not as dangerous as the Venus situation, could be dangerous for a large chunk of life on earth nevertheless.

    On the recent post about air-capture, it looks like we still might have some ability to slow or halt this bout of global warming, even if we exceed the CO2 level tipping point for a short time. It seems no one knows exactly how much CO2 equivalent in the atmosphere will put us at a tipping point (into hysteresis), tho they do seem to have an idea that a 3C warming would likely do that.

  32. 132
    Lawrence Brown says:

    “……….if there were greater than 22 flavors of quark, it was metastable, but as it turns out, there are 4).”

    Oops! My understanding is that there are 6.(Up,Down,Strange,Charm,Top and Bottom).

  33. 133
    Ray Ladbury says:

    Lawrence–of course you are right. I was suffering from brain flatulence. I am still a holdout for Truth and Beauty, myself–It’s the romantic in me!

  34. 134
    Miskolczi says:

    This is to Ray Ladbury (Says: 25 March 2008 at 8:07 PM)

    You are right, I am not an expert climatologist, I am just
    a physicist. But climatologist sometimes has to learn
    physics (meanwhile they can average temperature, ice cover

    Nowaday they are asking money for supercomputers I do not
    know why? It is quite sufficient to produce useless climate
    change predictions on a 100 km spatial resolution…

    They probably never heard of Von Neumann who pointed out long
    time ago that climate prediction is a boundary condition
    problem. If they do not put more physics into their GCM code
    they will keep coming up with nonsense.

    Where are you with your ‘finding a the kitchen
    sink in there’…you were given plenty of time.

    You know, there are two types of scientists. One is just
    talking, the other can prove what he is saying…which one
    you are? Well, NASA was not able to come up with any
    computations or resuls against the theory in six years, so I
    do not expect too much from you.

    In case you have some definite results to discuss I shall
    be happy to do so.

    [Response: Thanks for stopping by. Please leave the insinuations at home next time. - gavin]

  35. 135
    Ray Ladbury says:

    Ferenc Miskolczi (I presume), Climate science is not my day job. I do, however, know enough about it to realize 1)that the case for the current warming being caused by anthropogenic greenhouse gasses is not dependent in any way on GCM; 2)When a paramter is constrained by as many independent lines of evidence as CO2 forcing is, there’s not a lot of wiggle room.
    And actually there are many types of scientists (You’ve no doubt heard the one: There are 10 types of engineers–those who understand binary and those who don’t). The type of scientist I seek to be is one who is an expert in his own field and has sufficient grasp of the rest of physics that I can follow it and understand it. I would not presume that such a level of understanding exceeds that of the experts in the field. That is why I come to this site to learn from the experts in climate science. You are welcome to do so as well.

  36. 136
    Miskolczi says:

    Perfect Journals of raypierre:

    …’We could comment on it, but on the whole it’s more worthwhile to
    spend time commenting on things that have passed review in the more
    major journals and don’t have such obvious flaws (even if they
    nonetheless have flaws). –raypierre]’

    If people are interested, my answer to such comments may be found at this link:

    This much about the ‘Obscured Hungarian Journal’

  37. 137
    Miskolczi says:

    To Ray Ladbury #135:

    I came along to see the opinions of the experts about
    my article.

    My article is not about global warming.
    Global warming should be a proven fact based on
    measurements. If it is there, the question is what
    might be cause. The co2 level is also rising, it is
    another fact. But the way to the global average
    surface temperature is not via the co2 concentration,
    but via the total IR optical depth of the atmosphere
    and, a sound theoretical relationship which
    establishes the connection.

    From about 1920 the only available theoretical
    equation that related this two things is the Eddington
    equation developed for the semi-infinite atmospheres
    (of stars).

    Applying this to the Earth’s atmosphere is wrong, since
    for finite semi-transparent atmospheres the Eddington
    equation is invalid. This means that when a GCM (after
    correctly solving the local primitive equations with
    resonable spatial and temporal resolution) they arrive
    to the question of the global constraints. So far from
    the Eddington solution they have the linear-in optical
    depth relation which is incorrect.

    My paper shows, that (independently of the Kirchhoff’s
    law, virial theorem, cloudy energy balance equation etc.)
    the global average thermal structure of the atmosphere
    is a radiative equilibrium profile, with a global average
    IR optical depth of 1.87. The relationship between the
    surface temperature and outgoing IR radiation is not
    linear in the IR optical depth, but contains the IR flux

    According to this, the sensitivity of the surface temperature
    for GHG forcing is much less…I would like to see the comments
    of the experts on this.

    If people dismiss a paper (like ‘raypierre’), because it is
    in an ‘Obscured Hungarian Journal’, or because the consequences
    of the results are against the IPCC report, it is bad enough,
    and it is not in the interest of the improvement of our
    understanding the planetary greenhouse effect.

    [Response: I'm not dismissing the paper because it is in an obscure Hungarian journal. I mentioned that just to explain how a paper with so many elementary errors in it could pass peer review. The problem with the paper is that you understand neither Kirchoff's laws nor the Virial theorem -- nor even dimensional analysis, which would have caught your Virial error for you right away. Chris Colose, who is an undergraduate in the early stages of his study, in fact understands this all far better than you, as did the undergrads at Bowdoin. --raypierre]

  38. 138
    Miskolczi says:

    To response of raypierre:

    If you are so sensitive to the elementary errors did you comment
    the Kiehl-Trenberth IR planetary radiation budget?

    Kirchhoff law: I stated that Ed=Su(1-Ta) and I proved this
    relationship theoretically for a bounded semi-transparent
    radiative equilibrium atmosphere. I put a figure at the

    link. You probably would like to explain the shown relationship
    between the flux density terms to those who mistakenly attribute
    it to the Kirchhoff law.

    In case you manage to explain this figure or (Fig. 2 in the paper),
    we may go on to discuss dimensional analaysis and virial
    theorem. I am very much impressed with your students. My students
    have no problem to read this paper and understand what it wants to

    [Response: Your poor students. I won't spoil the surprise by stealing the thunder of the Bowdoin class. I'm going to give them the first shot at writing this up, even if it takes them a while since they have other class work to attend to as well. --raypierre]

  39. 139
    Chris Colose says:

    Eppur si muove

  40. 140
    Tim McDermott says:

    Chris (139), Thanks, that made me laugh.

  41. 141
    Jeffrey Chambers says:

    The Senate minority is using work such as Miskolczi in attempting to dubunk the idea of a scientific consensus on man-made warming. Seems a ripe time to discuss use of science in the Senate as a number of carbon control measures are debated soon. I’d say the Bowdoin class should tesify!

    Here is the Senate minority report:

    and then follow this link where Miskolczi is cited:

    Prominent Hungarian Physicist Dr. Miklós Zágoni, a former global warming activist who recently reversed his views about man-made climate fears and is now a skeptic, presented scientific findings at the conference refuting rising CO2 fears. Zágoni’s scientific mentor Hungarian scientist, Dr. Ferenc Miskolczi, an atmospheric physicist, resigned from his post working with NASA because he was disgusted with the agency’s lack of scientific freedom. Miskolczi, who also presented his peer-reviewed findings at the conference, said he wanted to release his new research that showed “runaway greenhouse theories contradict energy balance equations,” but he claims NASA refused to allow him.

  42. 142
    Neal J. King says:

    Dr. Miskolczi,

    I have been reading your paper, and I have the following questions:

    a) Virial Theorem:
    One of the essential new insights that you want to bring into the discussion is the application of the Virial Theorem. However, I find your actual discussion of it is very short and cryptic. In particular, you relate the upward flux from the atmosphere to the atmospheric kinetic energy, and the surface upward flux to the atmospheric potential energy. What does a flux have to do with a bulk energy? I would appreciate something more specific than what you have provided in Section 2(g) and Section 3.1.


    c) Your Equation (7):
    I don’t understand your argument for this equation. It seems to me that if it is a result of conservation of energy, it would be derivable from an examination of your Figure 1; but I can’t see any reasonable interpretation of (7) based on the fluxes and interfaces defined in Figure 1. Equations (1), (2) and (3) I can understand from that, but not (7).

    d) Your Equation (8):
    As a consequence of (7), you derive the relation S_u = (3/2) * OLR; which I believe is an important step in your derivation of a unique balancing condition. However, as a universal relationship, this seems highly suspicious. Let’s take the special case that the atmosphere is totally transparent to all radiation: this can be done by following a sequence of mathematical models parameterized by the IR-molecule interaction strength, finally reducing it to zero. Then, if we look at Figure 1, we would set all the arrows that terminate in/from the atmosphere to zero. When we do that, we find that OLR = S_u = F_0: the radiation comes in, is absorbed only by the ground, and is emitted only to space. So in that case,
    S_u = (1) * OLR, not (3/2) * OLR.

    So how did the firm factor of (3/2) disappear? Why doesn’t this general result apply in the trivial case? In the continuous reduction of an interaction parameter, at what point does the reasoning leading you to the (3/2) factor fail?


  43. 143
    stas peterson says:

    To Neal King,

    Your request to Dr. Miskolczi for evidence of Su = 3/2 OLR is produced like any good evidence.

    Miskolczi is an experimental scientist first. If you read his previous paper using the data from the satellites he published a mountain of data and frequency by frequency, LBL, summations.

    See his clear sky spectral decomposition paper of 2004, circa pages 200-225 especially 202 etc. Measured ratio of Su to OLR is about Su = 1.5 OLR.

    He obtained the basis for his theoretical analysis and discussion, the old fashioned way… he went out, conducted an experiment, and measured it.

    Unlike Milne,in the 1920s, he had access to the satellite data that give actual measures of OLR, and F.

    You can use numerical methods to “solve” a differential equation with computational methods that were never conceivable to Milne.

    Ask me sir, Is Mikolczi’s model of a finite atmosphere attached to a stable planetary surface, allowing for continuity equations driving temperatures convergence at the surface with a gravitationally bound, hence denser at the bottom fading to vacuum at the top, and thus allowing evaporation, rising columns of hot air, convection energy transport, and rain, a good model of Earth?

    Or do you think that Milne’s stellar model of a infinite atmosphere created to model a star, with no surface, all gas or plasma, attached to only a mythical discontinuity at its gaseous center, more resembling of the real Earth? Milne’s infinite atmosphere model equipped with purposeful deviations, to trick the model into semi-computable simplifications? If so, tell me why?

    How did Newton deduce an inverse square law? Why not an inverse cubic or inverse quartic law? Answer: He experimented, Measured and then analyzed to produce in inverse square relations that matched reality.

    [Response: Newton's law turns out to work almost everywhere. The counter example given above shows that Miskolczi's observation doesn't. Therefore it is unlikely to be a universal truth or be of any help in determining climate sensitivity. That the relationship was said to be derived theoretically when in fact it is just an approximation to his data is particularly concerning. - gavin]

  44. 144
    Ray Ladbury says:

    Re: Miskolczi, Gerlich & Tscheuschner et al.,

    Friends don’t let friends drink and derive.

  45. 145
    Neal J. King says:

    #143: stas peterson,

    As Gavin pointed out, my question was about the explanation of what is presented as a theoretical derivation. A theoretical derivation does not draw its validity from measurements, but from reasoning: If it matches the measurements, that agreement gives support to the assumptions. But since, as I showed, that factor of (3/2) must instead be a factor of (1) in the trivial case, then if the reasoning is actually correct in the non-trivial case, there should be some disruption in either the reasoning or the assumptions as the interaction between molecules and radiation vanishes. Where’s the disruption?

    A further point: In my original posting (#142), I originally had a point b). At my request, RealClimate staff edited this item out, because I came to doubt that point. After further study of the Virial Theorem, I have come to the following conclusion:

    - The Virial Theorem (VT) does apply to the case at hand. But it doesn’t give the result that Miskolczi is claiming:
    2*avg(KE) = avg(V), where V = mgz.

    - Why? The equation above is true when the V in question is what is causing the gas to cohere (e.g., a cloud of gas, or a star). In particular, it applies to central, power-law, forces (e.g., gravity). But what is causing the atmosphere to stick around is binding between the individual molecules and the planet Earth. That would be a power-law force except for the fact that the bottom limit of the atmosphere is defined by the ground: the potential well becomes infinite for all distances less than the Earth’s radius. That’s no power law!

    - The VT still applies, but the virial
    (sum of r_i . F_i)
    is no longer related in a transparent way to the potential energy due to the imposed external potential of the Earth’s gravity: It’s not equal to it.

    - Instead, if you do the actual calculation of the virial over a region of limited size (so that the mass density can be taken to be constant), you find that you get a term which equates to 2*avg(KE), another term which equates to 3*pressure*volume, a term that corresponds to the pressure difference in the vertical dimension, and a term that corresponds to the downward pull on the volume of gas. It also turns out that the first two terms are independent of the origin of the coordinates, but the second two terms each depend on the origin. That leads to the conclusion that the first two terms together imply the perfect-gas law; and the second two terms together imply the equation of hydrostatic equilibrium. You do not get anything extra that corresponds to the average gravitational potential energy avg(mgz): the avg(KE) term is tied to the pressure*volume term. (I’m sorry this presentation of results is so brief, but it would take a lot of space to explain this well.)

    - Indeed, as a separate exercise, you can take the model of an adiabatic atmosphere (
    and explicitly integrate KE and PE = mgz from bottom to top. When you do that, you find that 2*avg(KE) = 3*avg(PE), which doesn’t look anything like the VT for either 1-dimensional or 3-dimensional gravity.

    Finally, I have no opinion about Milne’s model applied to the atmosphere, as I haven’t studied it. I am just trying to understand what Miskolczi is doing. I believe I have identified some conceptual problems.

  46. 146
    John Olson says:

    I’ve noticed this Real Climate site still talks about global warming as established scientific fact.

    How did you all get past the inherent errors in satellite microwave sounding unit measurements? The methodology cannot be more accurate than +/- 1 degC (and is probably much less accurate), which means the intensive analysis of individual measurements can only produce a nice picture of satellite measurement instrument “noise”.

    Meanwhile, surface measurements do not include the polar regions, and vastly over-sample land areas in relation to ocean areas. No matter how sophisticated is the model used with this type of data, systemic errors cannot produce better climate statistics than the satellite data. Indeed, individual weather monitoring stations have been shown to produce warming data for a reason which has nothing to do with atmospheric composition: they appear to be measuring the local increases in surface temperature near growing rural, suburban and metropolitan areas.

    How are these systemic errors overcome in order to establish evidence for global warming — let alone a cause for such an hypothetical warming?

    I’ve heard it said in a number of places that the earth’s mean temperature is actually decreasing — trending downward for the last 10 years. As far as I know, mankind is pumping more CO2 than ever into the atmosphere. Do you agree, or do you take issue with the claim of global cooling? Why is it misleading or why is it correct?

  47. 147

    John Olson #146,

    I’ve heard it said in a number of places that the earth’s mean temperature is actually decreasing — trending downward for the last 10 years.

    Don’t believe everything you hear.

    And by the way, don’t you think the satellite and surface records agree pretty nicely — bumps, wiggles and all — in view of the fact that they are both impossible to be this precise?

    Perhaps those scientists know something you don’t ;-)

  48. 148
    David Donovan says:

    John Olson…

    Trying to get the last word in a near dead thread ?


    These questions have been addressed before…many times….

    Try the start-here link from the main page

    Also see..

    (scroll down a bit to the “problems with the temperature records” link )

  49. 149
    Jim Eager says:

    Each of these assertions have been addressed here at RC repeatedly. You would well advised to seek out the response(s) to them using the Start Here tab and the site search box before repeating them as you would then look much less foolish.

  50. 150

    John, your questions are all answered on this site. You can either keep reading various threads, where much of this has come up repeatedly, or you can look at the FAQs and scientific links.

    I will only tell you that the idea that “the earth’s mean temperature is actually decreasing — trending downward for the last 10 years” is a pure example of the “big lie” technique famously enunciated by Hitler’s PR guy, Goebbels, and I’m sorry that you have been mislead by those pushing it.

    Every data set we have shows a warming trend. Here is a useful starting point for you to verify this for yourself:

    If that is too much trouble, then I will reiterate here something I tell those who have a limited appetite for statistical analysis. Almost every year *since* 1998 (which I take to be “ten years ago” for practical purposes) has been warmer than almost every year before then. This fact alone should be enough to show you why the statement you repeat is at best highly misleading. Here is the actual ranking of top-ten warmest years (SR ’05 dataset, used by NCDC):

    Year Anomaly
    (J-D) (C) (F)
    2005 0.61 1.10
    1998 0.58 1.04
    2002 0.56 1.01
    2003 0.56 1.01
    2006 0.55 0.99
    2007 0.55 0.99
    2004 0.53 0.95
    2001 0.49 0.88
    2008 0.49 0.88
    1997 0.46 0.83

    (Note that of the years since 1998, only ’99 and 2000 don’t make this top ten list. Also how close places two through six are–close to the confidence interval, if I remember right, meaning that these years are pretty close to being “tied.”)

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