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Sun & climate: moving in opposite directions

What the science says...

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The sun's energy has decreased since the 1980s but the Earth keeps warming faster than before.

Climate Myth...

It's the sun

"Over the past few hundred years, there has been a steady increase in the numbers of sunspots, at the time when the Earth has been getting warmer. The data suggests solar activity is influencing the global climate causing the world to get warmer." (BBC)

At a glance

Thankfully for us, our Sun is a very average kind of star. That means it behaves stably over billions of years, steadily consuming its hydrogen fuel in the nuclear reaction that produces sunshine.

Solar stability, along with the Greenhouse Effect, combine to give our planet a habitable range of surface temperatures. In contrast, less stable stars can vary a lot in their radiation output. That lack of stability can prevent life, as we know it, from evolving on any planets that might orbit such stars.

That the Sun is a stable type of star is clearly demonstrated by the amount of Solar energy reaching Earth's average orbital position: it varies very little at all. This quantity, called the Total Solar Irradiance, has been measured for around forty years with high accuracy by sensitive instruments aboard satellites. Its average value is 1,362 watts per square metre. Irradiance fluctuates by about a watt either way, depending on where we are within the 11-year long sunspot cycle. That's a variation of no more than 0.15%.

From the early 1970s until today, the Solar radiation reaching the top of Earth's atmosphere has in fact shown a very slight decline. Through that same period, global temperatures have continued to increase. The two data records, incoming Solar energy and global temperature, have diverged. That means they have gone in opposite directions. If incoming Solar energy has decreased while the Earth continues to warm up, the Sun cannot be the control-knob of that warming.

Attempts to blame the sun for the rise in global temperatures have had to involve taking the data but selecting only the time periods that support such an argument. The remaining parts of the information - showing that divergence - have had to be ditched. Proper science study requires that all the available data be considered, not just a part of it. This particular sin is known as “cherry-picking”.

Please use this form to provide feedback about this new "At a glance" section, which was updated on May 27, 2023 to improve its readability. Read a more technical version below or dig deeper via the tabs above!

Further details

Our Sun is an average-sized main sequence star that is steadily using its hydrogen fuel, situated some 150 million kilometres away from Earth. That distance was first determined (with a small error) by a time consuming and complex set of measurements in the late 1700s. It led to the first systemic considerations of Earth's climate by Joseph Fourier in the 1820s. Fourier's number-crunching led him to realise a planet of Earth's size situated that far from the Sun ought to be significantly colder than it was. He was thereby laying the foundation stone for the line of enquiry that led after a few decades to the discovery of what we now call the Greenhouse Effect – and the way that effect changes in intensity as a response to rising or falling levels of the various greenhouse gases.

TSI Solar cycles

Figure 1: Plot of the observational record (1979-2022) on the scale of the TSIS-1 instrument currently flying on the space station. In this plot, the different records are all cross calibrated to the TSIS-1 absolute scale (e.g., the TSIS1-absolute scale is 0.858 W/m^2 higher than the SORCE absolute scale) so the variability of TSI in this plot is considered to be its “true variability” (within cross calibration uncertainties). Image: Judith Lean.

The Sun has a strong magnetic field, but one that is constantly on the move, to the extent that around every 11 years or so, Solar polarity flips: north becomes south, until another 11 years has passed when it flips back again. These Solar Cycles affect what happens at the surface of the Sun, such as the sunspots caused by those magnetic fields. Each cycle starts at Solar Minimum with very few or no sunspots, then rises mid-cycle towards Solar Maximum, where sunspots are numerous, before falling back towards the end. The total radiation emitted by the Sun – total solar irradiance (TSI) is the technical term – essentially defined as the solar flux at the Earth's orbital radius, fluctuates through this 11-year cycle by up to 0.15% between maximum and minimum.

Such short term and small fluctuations in TSI do not have a strong long term influence on Earth's climate: they are not large enough and as it's a cycle, they essentially cancel one another out. Over the longer term, more sustained changes in TSI over centuries are more important. This is why such information is included, along with other natural and human-driven influences, when running climate models, to ask them, “what if?"

An examination of the past 1150 years found temperatures to have closely matched solar activity for much of that time (Usoskin et al. 2005). But also for much of that time, greenhouse gas concentrations hardly varied at all. This led the study to conclude, " that at least this most recent warming episode must have another source."

TSI vs. T
Figure 2: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al. 2007. TSI from 1979 to 2015 from the World Radiation Center (see their PMOD index page for data updates). Plots of the most recent solar irradiance can be found at the Laboratory for Atmospheric and Space Physics LISIRD site.

The slight decline in Solar activity after 1975 was picked up through a number of independent measurements, so is definitely real. Over the last 45 years of global warming, Solar activity and global temperature have therefore been steadily diverging. In fact, an analysis of solar trends concluded that the sun has actually contributed a slight cooling influence into the mix that has driven global temperature through recent decades (Lockwood, 2008), but the massive increase in carbon-based greenhouse gases is the main forcing agent at present.

Other studies tend to agree. Foster & Rahmstorf (2011) used multiple linear regression to quantify and remove the effects of the El Niño Southern Oscillation (ENSO) and solar and volcanic activity from the surface and lower troposphere temperature data.  They found that from 1979 to 2010, solar activity had a very slight cooling effect of between -0.014 and -0.023°C per decade, depending on the data set. A more recent graphic, from the IPCC AR6, shows these trends to have continued.

AR6 WGI SPM Figure 1 Panel p

Figure 3: Figure SPM.1 (IPCC AR6 WGI SPM) - History of global temperature change and causes of recent warming panel (b). Changes in global surface temperature over the past 170 years (black line) relative to 1850–1900 and annually averaged, compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations (see Box SPM.1) of the temperature response to both human and natural drivers (brown) and to only natural drivers (solar and volcanic activity, green). For the full image and caption please click here or on the image.

Like Foster & Rahmstorf, Lean & Rind (2008) performed a multiple linear regression on the temperature data, and found that while solar activity can account for about 11% of the global warming from 1889 to 2006, it can only account for 1.6% of the warming from 1955 to 2005, and had a slight cooling effect (-0.004°C per decade) from 1979 to 2005.

Finally, physics does not support the claim that changes in TSI drive current climate change. If that claim had any credence, we would not expect to see the current situation, in which Earth's lower atmosphere is warming strongly whereas the upper atmosphere is cooling. That is exactly the pattern predicted by physics, in our situation where we have overloaded Earth's atmosphere with greenhouse gases. If warming was solely down to the Sun, we would expect the opposite pattern. In fact, the only way to propagate this myth nowadays involves cherry-picking everything prior to 1975 and completely disregarding all the more recent data. That's simply not science.

Longer-term variations in TSI received by Earth

It's also important to mention variations in TSI driven not by Solar energy output but by variations in Earth's orbit, that are of course independent of Solar activity. Such variations, however, take place over very long periods, described by the Milankovitch orbital cycles operating over tens of thousands of years. Those cycles determine the distance between Earth and the Sun at perihelion and aphelion and in addition the tilt the planet's axis of rotation: both affect how much heat-radiation the planet receives at the top of its atmosphere through time. But such fluctuations are nothing like the rapid changes we see in the weather, such as the difference between a sunny day and a cloudy one. The long time-factor ensures that.

Another even more obscure approach used to claim, "it's the sun" was (and probably still is in some quarters) to talk about, "indirect effects". To wit, when studies can't find a sufficiently large direct effect, bring even lesser factors to the fore, such as cosmic rays. Fail.

In conclusion, the recent, post 1975 steep rise in global temperatures are not reflected in TSI changes that have in fact exerted a slight cooling influence. Milankovitch cycles that operate over vastly bigger time-scales simply don't work quickly enough to change climate drastically over a few decades. Instead, the enormous rise in greenhouse gas concentrations over the same period is the primary forcing-agent. The physics predicted what is now being observed.

Last updated on 27 May 2023 by John Mason. View Archives

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Further viewing

Related video from Peter Sinclair's "Climate Denial Crock of the Week" series:

Further viewing

This video created by Andy Redwood in May 2020 is an interesting and creative interpretation of this rebuttal:

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Sun

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

Denial101x videos

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Additional video from the MOOC

Expert interview with Mike Lockwood


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Comments 426 to 450 out of 656:

  1. Gord - "You should recognize this number (342 w/m^2) from Trenberth's Energy Budget" I do recognize the number. "1367 w/m^2 is not an average and I did not identify it as such." Good, but it seems like you expect the average temperature of the Earth to be proportional to solar flux at one location at one time - which could work if the rest of the Earth were wrapped in aluminum foil (in which case the temperature of the surface of the Earth would approach the temperature corresponding to the solar flux at that one location/time) or a very thick blanket or subject to a strong greenhouse effect... ------- "First, this calculation is the one the AGW'ers use for an Earth without a "Greenhouse Effect", ie. no atmosphere:"...""Average Temperature of Earth = 255K or -18 deg C (240 w/m^2) due to the Sun and Earth's albedo = 0.3"" The albedo and greenhouse effect are partly linked by atmospheric components and behavior that contribute to both, but they are not automatically proportional to each other, and it is useful to identify their seperate roles. "There is absolutely no evidence that the Earth had an albedo of 0.3 before the Earth had an atmosphere." And who ever said otherwise? (Without an atmosphere, offhand I think it's somewhere around 0.1). "The AGW'ers have assumed the Earth, without an atmosphere, has an albedo of 0.3, exactly what they assume the Earth's albedo is with an atmosphere." NO, that is NOT what 'AGW's' are assuming at all. The albedo is known to be about 0.3 (PS this is a global time and area average weighted by TOA insolation, hence equal to the global time average reflection/backscattering to space of all solar radiation intercepted by the Earth.). Since the albedo is known seperately from how the greenhouse effect is known, it can be used in an equation to estimate the greenhouse effect. IN OTHER WORDS, The approx. 33 K warming effect is not from the difference between the atmosphere as it is and no atmosphere, it is the difference between the atmosphere as it is and the atmosphere as it is except for the greenhouse effect! ------- "- My calculations of the average temp of the Earth without an atmosphere would be +6 deg C, uses exactly the same method as the AGW'ers have used." Which is the (maximum possible global time average surface) temperature (when LW emissivity = 1; you can add about approx. 0.75 K for each 1 % decline in LW emissivity up to a point) with ZERO albedo AND ZERO greenhouse effect. THIS OFFERS YOUR ARGUMENT ZERO SUPPORT, BECAUSE YOU ARE SAYING THAT THERE IS NO GREENHOUSE EFFECT WHILE NOT DISPUTING THAT THE EARTH HAS AN ATMOSPHERE AND DOES HAVE AN ALBEDO OF ABOUT 0.3. "- My assumption that the 1367 w/m^2 would produce additional average warming (above the +6 deg C) is valid because the oceans would already be in liquid form and capable of heat storage and heat transfer by conduction and convection to the polar regions." Additional average warming relative to what? If that is additional, then remove the 1367 W/m2 insolation at noon at the equator from the global average insolation that you used to calculate global average temperature. The resulting average temperature will be lower, and then when you add the 1367 W/m2 over a limited area, you will get back to the same average temperature (or not, if you allow temperature variations over space, for reasons I previously explained). When the surface has a nonzero temperature, it emits radiation; in the approximation of a perfect blackbody at all LW wavelengths, it emits radiation in proportion to the fourth power of the temperature, in a relationship of which you evidently are aware. However heat is distributed from the locations where the temperature may get higher than 279 K (following your calculation for no atmosphere, zero albedo, zero greenhouse effect, LW emissivity = 1, for a temperature in radiative equilibrium with the global time average insolation), whereever the temperature is higher than 279 K, it will emit more radiant heat flux per unit area than is gained from the global time average solar heating. IF the global average temperature is greater than 279 K (for the given assumptions), then the Earth will be losing more heat than it is gaining from the sun and the temperature will drop until it reaches 279 K - or even lower if there are temperature variations, because the emitted energy flux increase for higher temperatures is greater than the decrease for lower temperatures, and thus temperature variation requires a lower global time average temperature for equilibrium. "- The calculation takes the Earth temperature to a level above some of the known Ice Age temperature's when an atmosphere was clearly present." And when there was clearly higher albedo from snow and ice, and clearly less CO2. By the way, maybe I neglected to mention this earlier, or maybe I didn't bother to here because it is in one of my comments elsewhere that I suggested to you, but NOT ONLY CAN THE ALBEDO BE OBSERVED DIRECTLY, the GREENHOUSE EFFECT CAN BE OBSERVED DIRECTLY. SATELLITES CAN MEASURE THE LW FLUXES IN SPACE FROM THE EARTH BELOW AND THE COOL ATMOSPHERE CAN BE SEEN - ON AVERAGE AND IN GENERAL THE EARTH LITERALLY LOOKS COLDER FROM SPACE THAN THE SURFACE TEMPERATURE IS - THERE ARE NOTABLE VARIATIONS IN THIS EFFECT, SPATIALLY in part DUE TO CLOUDS (THOSE INFRARED SATELLITE IMAGES SEEN IN WEATHER REPORTS SHOW CLOUD TOP TEMPERATURE) AND OVER THE SPECTRUM where the SIGNATURES OF H2O vapor and CO2, and some other gases, ARE READILY IDENTIFIABLE - IT CAN BE SEEN FROM SPACE THAT CLOUDS, CO2, H2O, etc, BLOCK THE GREATER RADIATION FLUX FROM THE WARMER SURFACE. THIS CAN ALSO BE SEEN ON OTHER PLANETS (WITH VARIATIONS DUE TO LACK OF H2O, DIFFERENT TEMPERATURE PROFILES, ETC.). ------------------ "Like I said: Who needs a "greenhouse effect" to explain the warming of the Earth? can easily be explained that all the warming came from the SUN....the ONLY energy source! " Maybe you've been getting confused between ultimate source (not quite, since the energy from the sun's surface comes from nuclear fusion, that comes from nuclear potential energy that came from the big bang...) and proximate source. The Earth and atmosphere have some internal energy and enthalpy stored up, and can at any one moment act as proximate heat sources. This is obvious at night, since the Earth continues to radiate to space on its dark side. The atmosphere can in times and places (most obviously whenever a low level inversion occurs) transfer heat to the surface. IF the sun's heating were taken away, the Earth and atmosphere would not go to near absolute zero temperature (or its new colder equilibirum temperature, given geothermal and tidal heating) instantly; the temperature would decay (roughly exponentially) in time toward the new equilibrium as heat leaves the Earth and atmosphere; the geothermal and tidal heat supply to the surface is roughly 1/2400 (or a bit less) of the solar heating of the Earth and atmosphere, so the new equilibrium temperature (with no greenhouse effect) would be approx. 1/7 of 255 K, or about 36 K. "- The other energy source available (the Earth's molten core) and subsequent Earth warming due to Volcanic activity and heat vents would also contribute to the Earth's warming. (This was ignored in my analysis because the AGW'ers have also, wrongly, ignored this energy source in their "faulty" analysis)" NOT WRONGLY IGNORED, JUSIFIABLY IGNORED BECAUSE IT's ONLY ABOUT 0.1 W/m2. "The SUN and the Earth's Molten Core (the ONLY energy sources) are responsible for the Earth's temperature not some "perpetual motion machine in a postive feedback loop"." AND WHO IS SAYING OTHERWISE BESIDES YOU? "- The "greenhouse effect" is clearly a perpetual motion machine in a postive feedback IMPOSSIBLE occurance." THE SAME LOGIC SUGGESTS THAT IF YOU WRAP HOT CHICKEN IN ALUMINUM FOIL, THE CHICKEN STILL COOLS OFF AS RAPIDLY, EVEN IF CONDUCTION AND CONVECTION HAVE NOTHING TO DO WITH IT. THE SAME LOGIC SUGGESTS THAT ... WELL, WE'VE BEEN OVER THAT AD NAUSEUM. -------------------
  2. "- The calculation takes the Earth temperature to a level above some of the known Ice Age temperature's when an atmosphere was clearly present." ... Actually, you'd just barely make it to ice age global average temperature if the emissivity in LW were about 0.96, so that the temperature would be about 9 deg C. Or, allowing some uncertainty in the absolute global average temperature ('absolute' - not because deg C is more accurate; I mean 'absolute' as opposed to relative - ie warming or cooling), maybe you just get into the possible range... maybe (?). But that's all undone by the fact that there is an albedo of 0.3, which would be slightly larger during the ice ages than now.
  3. Dan Pangburn - I responded to you at: But I will also post it here: Dan Pangburn - you misunderstood the intent of the labels and flows shown. 1. clarifications: At each wavelength and along each direction, each layer of air emits and absorbs in proportion to (1-transmissivity) (setting aside scattering, which is a minor issue for longwave radiation under Earthly conditions). Thus the portion of energy from any one layer that reaches any one other layer (or surface) decays exponentially with optical path length, and the portion that is absorbed over a distance is equal to the decay over that distance. When integrating over wavelengths and directions, the decay is not quite exponential, though it tends to be qualitatively similar (the exponential decay rate decreases since the remaining portion is increasingly at wavelengths where there is greater transparency, and is increasingly concentrated into the range of directions (solid angle) closer to vertical (optical path length per unit vertical distance is inversely proportional to the cosine of the angle from vertical). Even without clouds and aside from horizontal differences in humidity, optical path length per unit vertical distance also varies with height. This is partly because some gases - water vapor and ozone in particular, vary in relative concentration greatly with height; water vapor concentration relative to air tends to decrease roughly exponentially with height within the troposphere, and has less effect on radiation that is emitted directly to space than it would if it were evenly distributed (the CO2, etc, and any high level clouds are 'in front' of the lower-lying H2O, etc, in as far as upward radiation to space is concerned). This is also because the spectra of gases is affected by pressure and doppler broadening of absorption/emission lines, and these things vary with height - within the troposphere, they both decrease with height, so that the absorptivity and emissivity of an optically thin layer is more concentrated toward line centers higher up. (I think the effect of pressure broadenning dominates even into a portion of the stratosphere - not sure where doppler broadenning becomes more important, but it might be where the air is too optically thin for it to make much difference (?).) 2. More to the point of your question: The fluxes that are shown are not to and from each layer of air or clouds, but the total that reaches the surface and that reaches space from all layers of air, and the total from the surface that is absorbed over layers of air, and does not explicitly show the radiative energy transfers between different layers of air, and thus does not show the fluxes from layers of air that are absorbed by other layers of air. 1. - on line broadenning consequences - lack of broadenning increases the tranmission in more transparent gaps between line centers and concentrates emissivitity/absorptivity of a thin layer toward the line centers. When, over a sufficient distance, the absorptivity at and near line centers approaches 1 (when the optical path length gets large), increasing the absorptivity of thinner layers does not contribute much more to the absorptivity over such a distance because of overlap (saturation), so the effect of reduced broadenningover a larger interval of wavelengths is to increase transmission. 2. - For example, of the radiation from the atmosphere that reaches the surface, some portion of that is from any given layer of air; the portion that is from a layer of air is only a fraction of the total emitted by that layer of air in the direction of the surface. ----------------------- "K&T also assume an emissivity of one which would be correct if earth was a perfect black body. It is close but noticeably different (14 W m-2 less) at a more realistic emissivity of 0.98." Kiehl and Trenberth do use the surface = perfect blackbody simplifying assumption, but not because they don't know it not to be true; it is just a useful approximation. (Though perhaps not so useful in this case, considering it should be relatively easy to use a non-unity emmisivity in calculations, especially if it is wavelength invariant, though it probably varies a little bit... well, there's the complexity, I guess; still, the results are approximately correct in that regard - Kiehl and Trenberth also explicitly note some other simplifications; this calculation is not for an actual 4-dimensional (time included) climate system but for representative conditions for all global area over the full day and full year, represented as a single column of atmosphere in steady-state optical and temperature conditions. They discuss this in their paper. They also mention that the apportionment of solar radiation absorption between the surface and atmosphere is particularly uncertain, as it is hard to constrain by observations thus far, although it must be in balance with convective and radiative fluxes between the surface and atmosphere and radiative fluxes to space. (Note this, Gord: Kiehl and Trenberth use conservation of energy to construct the energy budget.) ) I have actually been uncertain about the emmissivity of the surface. A LW emmisivity of 0.98 raises the equilibrium temperature of the surface by roughly 1.5 K in the absence of a greenhouse effect (with temperatures roughly near 300 K; it is proportional to the surface temperature). With a greenhouse effect, the effective emitting temperature of the Earth to space is less affected by the surface LW emissivity because it is partly hidden by the atmosphere's own LW opacity; thus, a nonzero LW albedo somewhat reduces the warming from increasing atmospheric LW opacity (by no more than about 1.5 K (in total relative to the temperature with no greenhouse effect, not for each increase that is made in the greenhouse effect) if the surface emissivity is 0.98 and the surface temperatures involved are roughly near 300 K). Between the surface and the distribution of absorption of surface radiation within the atmosphere, the reduction in net upward LW radiation between due to the reduced emmission from the surface is partly compensated by the reflection of downward atmospheric radiation back up by the (1 - LW emissivity) LW albedo. In W/m2: with radiation emitted from the surface = 390 (350 to the atmosphere and 40 to space)with emissivity of 1 and radiation from the atmosphere to the surface being 324 (so the net upward LW flux at the surface is 390 - 324 = 66), a reduction in surface LW emissivity from 1 to 0.98 results in (with temperatures held constant): surface emission = 382.2 (reduction of 7.8) (343 to the atmosphere (reduction of 7) and 39.2 to space (reduction of 0.8)); atmospheric emission downward at the surface still 324; atmospheric emission to the surface (and absorbed) = 317.52 (reduction of 6.48), and atmospheric emission reflected at the surface = 6.48; so the net upward LW flux at the surface is 382.2 - 317.52 = 64.68, a reduction of 7.8 - 6.48 = 1.32. Some portion of the atmospheric radiation reflected at the surface goes to space; it is not necessarily the same fraction as the fraction of surface emission that reaches space, because the spectral distribution is difference because the atmosphere - even the part(s) radiating to the surface, are a bit cooler (generally) than the surface, and it is also likely less than the fraction of surface radiation that reaches space because it will be somewhat concentrated into wavelength intervals where the atmosphere is more opaque. But assuming that the fraction of radiation emitted from the surface that reaches space (40/390 = 39.2/382.2 ~= 10.3 %) is an upper limit, of the 6.48 of atmospheric radiation reflected at the surface, less than about 0.65 would go to space. That would partly offset the reduction in radiation to space from surface emission. --------- "In the thermodynamic sense, one must attend to where the system boundary is drawn." Of course. Climate scientists would readily understand where the boundaries are in such a diagram, and reading the accompanying text would illuminate that to others (I realize the updated version is only the diagram and not the text; I can tell you that this diagram treats the atmosphere for the most part as a single component that emits in either direction from varying depths within itself (hence it appears colder to space than from below because the colder part is more visible from space, etc.) as opposed to seperate layers with their own fluxes, except with the portion of radiation to space that comes from clouds being identified seperately).
  4. Gord - "Instead of, rationally, questioning if their average Earth temperature is correct or if they have under-estimated the energy provided by the ONLY energy source (the SUN), they immediately assume this difference in energy is due to the effects of the GHGs, convection, evaporation of water from the oceans, clouds, aerosols, etc." Immediately assume? No, the optical properties of CO2 and H2O, clouds, etc, have been studied, and from that, calculations - which require much number-crunching but are based on very straightforward mathematics and physics - result in a greenhouse effect model. Futhermore, we have the observations that the Earth's surface temperature is warmer than it would be, by approx. 30 or 33 K (yes, there is a little uncertainty), than it would be if there were no greenhouse effect, PLUS observations from space that show that the emissions to space are as if the Earth were much colder at some wavelengths and where there are high clouds then the temperature of the surface below is, and yet as if the Earth is not so cold between about 8 and 12 microns where there are not clouds - and this is of course because the temperature of the air, and thus the clouds and the gases in the air, are generally colder than the surface, especially higher in the troposphere and lower stratosphere - while no sizable dip in LW surface emissivity - such as a huge drop near 15 microns or whereever there are high cloud tops - has been found. AND THERE IS NO CONFLICT WITH THERMODYNAMICS OR CONSERVATION OF ENERGY. "Are GHGs, convection, evaporation of water from the oceans, clouds, aerosols, etc. energy sources?"..."The inference that GHGs etc can somehow "create" energy is not only an obviously wrong violates the Law of Conservation of Energy."..."Further, the assumption that the cooler atmosphere can transfer heat energy to a warmer Earth is a violation of the 2nd Law of Thermodynamics." You're still saying this stuff? - you must either be really stupid, really not want to learn, or have a lot of time to waste. 1. The energy budgets such as those of Kiehl and Trenberth, for an equilibrium climate, show energy fluxes whose convergences or divergences all sum to zero. That is, take each component besides the sun (effectively the ultimate source) and space (ultimate sink) - the surface, the atmosphere as a whole or in seperate layers - and add all energy inputs and add all energy outputs and subtract the outputs from the inputs and for each component you get zero. Furthermore, if you got something other than zero, this alone does not constitute creation or destruction of energy - energy can be assumed conserved, implying that what you have is a rate of energy storage, generally (except for phase transitions) corresponding to a rate of temperature change - this would occur over long time periods for a non-equilibrium climate, or for shorter time periods for the daily and annual cycles and for some internal variability. Your insistance otherwise shows an unwillingness to do simple arithmetic when the results would not support your desired conclusion. 2. This bit about the second law - I and many many others would disagree and have reason to do so (such as the emission or nonemission, and absorption or nonabsorption of a photon being dependent on local conditions and not some event in the future or something far away that an individual photon carries no information about - except maybe where quantum entanglement is involved (?), which is not really applicable here so far as I know), BUT we could agree to disagree about whether each individual 'opposing field' constitutes an energy flux in its own right or whether the resultant is the only real flux - the mathematics about the net energy flux works out the same either way. Except for the microscopic processes involved, and assuming approximately steady state conditions relative to the time it takes for photons to travel through the atmosphere, our disagreement could be treated as philosophical and not affecting the measurable outcomes, greenhouse effect or not. You seemed to allow that a hot object loses heat radiatively more slowly to a cooler object if the cooler object is made warmer. You could choose to understand the backradiation from the atmosphere to the surface as being an opposing field whose effect is merely to slow the 'actual' heat loss from the surface. Mathematically, you really have no basis for claiming that the greenhouse effect violates any physical laws because that is ultimately what it is about; the net radiant heat flux from hot to cold depends on each layer's temperature, each layer's emissivity, and the transparency of whatever is between them - how could you deny that? "Actual measurements conclusively show that the back-radiation cannot reach and heat the Earth. (see my post #246)."..."In fact, all the back-radiation measurements done by the AGW'ers use instruments that comply with the 2nd Law: 1. Direct measurements require the detector to be cooled below the atmospheric temp. 2. Indirect measurements measure the loss of energy (eg.Thermistor) to the cooler atmosphere."..."You would think that these "scientists" would be aware that the operation of their measuring instruments contradict the theory they are trying to prove!" All those examples you provided are at best (for you) qualitatively ambiguous with regards to who's version of the climate system energy flow is correct, though it's possible, depending on heat capacity and thermal conductivity, that the enhanced cooling of an object in the mirror that shields it from radiation from near the horizon actually proves that there is backradiation from the atmosphere (or an opposing field that would slow the cooling of the object, if you prefer). But from other physics knowlege, we know how things work... "They seem oblivious to the fact that if back-radiation energy actually reached the Earth's surface our energy problems would be over."..."All Solar Ovens (Parabolic Mirrors that concentrate Solar and IR energy at a focal point), including the major Mega-Watt installations, would produce energy at NIGHT!"..."In fact, they would produce MORE energy at NIGHT than they do during the DAY.....because the Back-Radiation (324 w/m^2) EXCEEDS the Solar Energy reaching the Earth (235 w/m^2)!" NO, 1. during the day, the total downward radiation would be solar + backradiation, not just solar, and while most of the atmopshere has a very small diurnal temperature range, the lowest part of the atmosphere would tend to add a diurnal cycle to the backradiation. 2. Backradiation, as with solar radiation filtering through thick clouds, is diffuse and cannot be focussed much (you could focus radiation scattered by a cloud that does not take up the whole sky, but only to the point that it would take up an entire hemisphere of view from the focal point; likewise, the greater dimness of backradiation from straight up relative to closer to the horizon is what is being focussed by solar ovens used to cool at night; this is much more spread out then the direct rays of the sun, and even if the atmosphere were removed entirely, the maximum possible cooling rate is set by the temperature, size, and optical properties of the object being cooled. 3. The relative inability to focus diffuse radiation is related to the entropy of the radiation; blackbody radiation from a colder surface has greater entropy per unit energy and thus less of it can be converted to useful work by a heat engine (or photovoltaic device, chemical reaction, etc.) for a given heat sink temperature. If the heat sink is near the surface temperature of the Earth, then except in an inversion, atmospheric radiation could not be converted to work at all. However, a fraction of heat in general from the Earth to the atmosphere can be converted to work, and while this doesn't happen naturally with radiation, a fraction of the convective flux is converted to the kinetic energy we observe as wind (it still ultimately ends up as heat because of where the energy from the winds goes).
  5. Patrick - It appears that you still do not understand my post. The calculations are for an Earth WITHOUT AN ATMOSPHERE. --- First: You quoted me as saying: "There is absolutely no evidence that the Earth had an albedo of 0.3 before the Earth had an atmosphere." What I actually said was: "There is absolutely no evidence that the Earth had an albedo of 0.3 before the Earth had an atmosphere, so my assumption of zero albedo is just as valid." --- You asked: "And who ever said otherwise? (Without an atmosphere, offhand I think it's somewhere around 0.1)." The AGW'ers who did this calculation, used 0.3! This calculation is the one the AGW'ers use for an Earth without a "Greenhouse Effect", ie. no atmosphere: "Average Temperature of Earth = 255K or -18 deg C (240 w/m^2) due to the Sun and Earth's albedo = 0.3" ---- You said.. "NO, that is NOT what 'AGW's' are assuming at all. The albedo is known to be about 0.3 (PS this is a global time and area average weighted by TOA insolation, hence equal to the global time average reflection/backscattering to space of all solar radiation intercepted by the Earth.). Since the albedo is known seperately from how the greenhouse effect is known, it can be used in an equation to estimate the greenhouse effect. IN OTHER WORDS, The approx. 33 K warming effect is not from the difference between the atmosphere as it is and no atmosphere, it is the difference between the atmosphere as it is and the atmosphere as it is except for the greenhouse effect!" Answer: Greenhouse effect "In the absence of the greenhouse effect and an atmosphere, the Earth's average surface temperature of 14 deg C (57 deg F) could be as low as −18 deg C (−0.4 deg F), the black body temperature of the Earth." Earth's Atmosphere Functions of the Atmosphere "Makes possible a mean temperature on Earth's surface of +15 deg C instead of -18 deg C as would be without atmosphere." Why is the Earth so warm? "If there was no atmosphere, the Earth's temperature could be calculated by balancing: The energy in sunlight absorbed by the Earth The energy radiated as infrared photons by the warm Earth. Equilibrium Temperature should be T=260 K " "The Greenhouse Effect is responsible for making the Earth about 35K warmer than it would be if there it had no atmosphere." Effect on Surface Temperature "The natural greenhouse effect raises the Earth’s surface temperature to about 15 degrees Celsius on average—more than 30 degrees warmer than it would be if it didn’t have an atmosphere." -------- Your post primarily deals with an Earth albedo of 0.3 in the presence of an atmosphere, which is not what was calculated. The rest of your rambling post covering your opinions on everything from the "big bang" to "chickens wraped in aluminum foil" are good comedy as well.
  6. Patrick - Your rambling post #448 is also rife with errors and a real hoot! Far too many errors and unsupported opinions to go into right now (and very tedious). Comedy is your strong point.
  7. Gord - --- " You quoted me as saying: "There is absolutely no evidence that the Earth had an albedo of 0.3 before the Earth had an atmosphere." What I actually said was: "There is absolutely no evidence that the Earth had an albedo of 0.3 before the Earth had an atmosphere, so my assumption of zero albedo is just as valid." " --- ... just as valid as some other erroneous assumption - speaking of which: About your quotes from: So they were sloppy in their explanations to the public on that point. It is obvious from the context that they are refering to the effect of the atmospheric greenhouse effect, seperate from atmospheric albedo contributions. Re 450 - So any physics that is inconvenient for YOU is "rambling", full of "errors and unsupported opinions"? What else is new. (Go look it up in textbooks and encyclopedias, or "hyperphysics" - I'm really just telling you common knowledge. You *almost* might as well criticize me for stating 1+1=2 without backing it up with examples and/or proof.) If you find it so tedious, maybe you aren't qualified to make those judgements. One possible error I made was in not considering that interference patterns among different photons - whose wavefronts will tend to spread sideways as they propagate (diffraction) could affect the absorption (or emission?) of an individual photon even when the other photons continue unaffected; however, if/when this is the case (I presume it is possible, in part because of how a photons' own interference pattern with itself in a double slit experiment affects the probability distribution of where it is absorbed) would still occur via effects on local conditions. It also still doesn't offer a possible mechanism that might somehow someway prevent the absorption by a warmer object of photons from a cooler object, because a hot object with lower emissivitiy, especially at shorter wavelengths, would produce an identical photon population. But again, the second law of thermodynamics is saved because the emissivity of the cooler object, if in local thermodynamic equilibrium, is equal to its absorptivity (at each individual wavelength), so that however much it emits to a a warmer object that is absorbed by the warmer object, it still must absorb more from the emission by the warmer object. Now, if they are seperated by a distance and alternately covered and exposed, and/or change temperature, at some relatively fast rate compared to the time for radiation to travel the distance, then it's more complicated, but... ------------- You're tilting at windmills. It would be comedic if it weren't tragic and perhaps just a bit scary.
  8. Patrick 027 444 The point is that Control Theory shows that Climate Scientists, in claiming AGW, have made a mistake in not being aware that added atmospheric carbon dioxide has no significant effect on average global temperature. As a result, they have misled a lot of people. The important ones are the politicians who have been crippling the world economy and are contemplating crippling the US economy to solve a non-problem.
  9. Dan - "in not being aware that added atmospheric carbon dioxide has no significant effect on average global temperature" - the point is that I don't see how Control Theory justifies such a conclusion. It would help if you explained what you would expect to see from a system that has positive feedbacks; I see nothing to indicate that the climate sensitivity is not in the range where it is thought to be. (It would also help if you explained how, whatever the cause, the temperature rise of the last century and especially the last few decades can be explained without a positive feedback.)
  10. A simplistic model often suffices better to demonstrate a point: At night the earth emits (say) 400w in radiation and its' temperature falls as a result. 10% goes straight out to space (40w) The atmosphere absorbs 360w And radiates 180w to space And radiates 180 back to earth Which absorbs this radiation and rises in temperaure. The net effect is that in that portion of time the earth disposed of 220w and thus the rate at which it cools is decreased by the presence of GG's. I don't know the exact details of the experiment to determine 'backradiation at night' but there are obviously some difficulties like - how did they ensure the dish wasn't warmer than the sky? Is there a website describing the experiment?
  11. Patrick 027 447 Apparently you did not notice that nearly all of the numbers on the revised K&T chart are different from the numbers on their 1997 chart. For those who did not pursue the link regarding the K&T update, these are the comments that I made there. “Are they unaware that most absorption takes place close the emitting surface? The graphic is misleading. Still.” “The graphic shows the 356 going all the way to the clouds and from the clouds 333 all the way back to the ground. Since GHGs absorb the IR, the intensity has to decline along the way. Barrett calculates 72.9% is absorbed within 100 meters, using the HITRAN database.” I am surprised that no one had challenged this chart before. Climatologists discovered long ago that some of the absorbed IR radiation is thermalized, that is, it raises the temperature of the air. Climate models didn’t work at all until convection (heat rises) was included in the mid 60s. “…in the real world by the upward convection of heat.” Spencer Weart at . The chart clearly shows Surface Radiation 396 with 356 of this going clear to the clouds. It is misleading because first it’s closer to 382 than 396 and second there is no indication that some of this (I calculate 59) must get thermalized. The rest, except for the 40 that go all the way out, gets radiated back. The graphic also shows 333 coming from the clouds. This too is misleading since only a fraction of the radiation that leaves the clouds (my guess about 35) gets all the way from the clouds to the ground.
  12. Patrick - You said.. "So they were sloppy in their explanations to the public on that point. It is obvious from the context that they are refering to the effect of the atmospheric greenhouse effect, seperate from atmospheric albedo contributions." --- No, the thing that is very obvious is that they all say NO ATMOSPHERE! "In the absence of the greenhouse effect and an atmosphere.." "....without atmosphere." " had no atmosphere." " didn’t have an atmosphere." See how tedious it becomes to demonstate an obvious point to you? Anyone capable of understanding the English language and old enough to know what the atmosphere is would easily understand what these links said. Yet, for Patrick, the words "NO ATMOSPHERE" somehow has a different meaning. ---------- Patrick, as I have said numerous times, you just don't have clue about any "established science". But, that certainly does not prevent you from trying to continually disprove or re-write Laws of Science....all based on your hilarious opinions. For you 1 + 1 = anything but 2. It's a good thing that you are an amateur (and that's being very generous in your case). At least you are not a threat to public safety.
  13. Mizimi - You said.... "The atmosphere absorbs 360w And radiates 180w to space And radiates 180 back to earth Which absorbs this radiation and rises in temperaure." --- First, if the atmosphere absorbed 360 w/m^2, it would radiate 360 w/m^2 in all directions...not half up and half down. (see Stefan-Boltzmann Law) Second, it is impossible for the colder atmosphere to transfer any heat energy back to the warmer Earth. It violates: 1. The 2nd Law of Thermodynamics "Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object." 2. Heat Radiation between hot and colder objects P = e*BC*A(T^4 - Tc^4) Where P = net radiated power (Watts), e = emissivity, BC = Stefan's constant, A = area, T = temperature of radiator in Kelvin and Tc = temperature of the surroundings or another body. 3. The Law of Conservation of Energy (Energy cannot be created or destroyed) The atmosphere was heated by the Earth's radiation. The energy used to heat the atmosphere CANNOT be used to heat the Earth because it came from the Earth. If it did heat the Earth, energy would have been created....a violation of The Law of Conservation of Energy. It would also violate Electromagnetic Physics, Vector Mathematics etc. and ALL existing measurements. --------------------- Mizimi, yes there is a website that you can visit regarding the Solar Oven experiment. Here is a partial re-post of mine: --- Solar Cookers and Other Cooking Alternatives "The second area of solar cookers I looked at was their potential use for cooling. I tested to see how effective they are at cooling both at night and during the day. During both times, the solar cooker needs to be aimed away from buildings, and trees. These objects have thermal radiation and will reduce the cooling effects. At night the solar cooker needs to also be aimed straight up towards the cold sky. During the day the solar cooker needs to be turned so that it does not face the Sun and also points towards the sky. For both time periods cooling should be possible because all bodies emit thermal radiation by virtue of their temperature. So the heat should be radiated outward. Cooling should occur because of the second law of thermodynamics which states that heat will flow naturally from a hot object to a cold object. The sky and upper atmosphere will be at a lower temperature then the cooking vessel. The average high-atmosphere temperature is approximately -20 °C. So the heat should be radiated from the cooking vessel to the atmosphere." --- This above link shows that heating cannot occur from the atmosphere. In fact, the article shows how to COOL items placed in the Solar Oven at NIGHT AND DAY! All you have to do is point the Oven away from the Sun during the Day and the Oven will transfer heat from the WARM object in the Oven to the COOLER atmosphere! It can even be used to produce ICE when the ambient air temp is +6 deg C! "If at night the temperature was within 6 °C or 10°F of freezing, nighttime cooling could be used to create ice. Previous tests at BYU (in the autumn and with less water)achieved ice formation by 8 a.m. when the minimum ambient night-time temperature was about 48 °F." This confirms the validity of 2nd Law of Thermodynamics....heat energy CANNOT flow from Cold to Warm objects. --- PS. This method is also used to measure "Back-radiation" indirectly. Ex. Indirect measurements measure the loss of energy (eg.Thermistor) to the cooler atmosphere.
  14. Dan - I did notice the numbers had been adjusted, I just used the older numbers that are nearly the same to illustrate my points. I didn't mean to cause confusion. Surface LW emissivity - I had inferred a value of about 0.96 (or maybe 0.95) from another source (Hartmann, "Global Physical Climatology", 1994, p.28) - specifically, this source states a surface emission of about 376.2 W/m2, which, if the temperature is 288 K (at which, blackbody radiation ~= 390.1 W/m2 (1 place beyond significant figures; I am using sigma = 5.67e-8)), implies a LW emissivity of 0.964; - on the other hand, the global and temporal variation of surface temperature might boost the global average surface emission so that it would correspond to a temperature 1 K higher than the actual global average (because radiation varies with the fourth power of temperature, so the areas with T>average T add more to the global average emission than the areas with T
  15. Gord - "No, the thing that is very obvious is that they all say NO ATMOSPHERE!" I was giving them the benifit of the doubt - maybe I shouldn't do that for the wikipedia source, but I would think the people at NASA are at least as knowledgable on the subject as I am, so I figured they must have meant to refer to the atmospheric greenhouse effect, and not the effects of changing any atmospheric contribution to global albedo. I know that the 33 K warming effect is calculated for a greenhouse effect vs no greenhouse effect with the albedo being invariant at 0.3 in both cases. But you seem to be grasping at straws, because - you can calculate the temperature for no greenhouse effect for whatever albedo you like, but you haven't made any case that the albedo is significantly different than 0.3 in actuality. No, I'm not saying that you said that you did. My point is that you were trying to argue that there is no greenhouse effect. But you KNOW the albedo is 0.3. So what is the point of a calculation with an albedo of 0 or 0.1?
  16. Gord - "First, if the atmosphere absorbed 360 w/m^2, it would radiate 360 w/m^2 in all directions...not half up and half down. (see Stefan-Boltzmann Law)" First, I haven't checked it just today but I presume that portion of the "hyperphysics" website is accurate ( I can't say the same of what you think you learned from it), and would also encourage Mizimi to explore that website. True that Mizimi is incorrect in the assumption that the upward and downward radiative fluxes are equal (though it's an okay first guess) - they could be under some circumstances, but the upward flux from the atmosphere at the tropopause and the top of the atmosphere will generally be less than the downward flux at the bottom of the atmosphere to the surface. But why would the atmopshere emit 360 W/m2 up from it's top and down from it's base, given 1. emissions are a function of temperature, and not directly on how much radiation is absorbed, though their is certainly a causal link - and 2. there are variations in temperature within the atmosphere.
  17. Gord - your comment 457: "1. The 2nd Law of Thermodynamics" "Energy will not flow spontaneously from a low temperature object to a higher temperature object." Net energy. Otherwise the website contradicts itself with statements about net radiation loss. "2. Heat Radiation between hot and colder objects" "P = e*BC*A(T^4 - Tc^4)" When both the hot object and colder object have emissivities e and ec that could be less than 1, and there is a layer between with transmissivity T: P = (e*ec*T)*BC*A(T^4 - Tc^4)" Or let U = e*ec*T*BC*A, so that P = U * (T^4 - Tc^4) This can be rewritten as: P = U*T^4 - U*Tc^4 (More generally, e, ec, and U could all vary with wavelength, and wavelength-dependent emission is a more complicated function of temperature, thout at all wavelenght an increase in T results in an increase in emission if e is constant.) The two terms on the right are opposing energy fluxes - you would call them opposing fields and not consider their energy fluxes to be real in their own right. However, in restating this formula, you have essentially admitted that you have no mathematical basis for denying the greenhouse effect, and in particular, backradiation from the atmosphere, which corresponds to the Tc term above in the fluxes between the surface and atmosphere. Your primary disagreement is a matter of labeling and, except for the microscopic basis of macroscopic phenomena, philosophical; You would have to accept that, at least mathematically, the greenhouse effect works as I and others say it does, even if you disagree about whether two opposing radiation fields can have two opposing energy fluxes. "3. The Law of Conservation of Energy (Energy cannot be created or destroyed)" "The atmosphere was heated by the Earth's radiation. The energy used to heat the atmosphere CANNOT be used to heat the Earth because it came from the Earth. If it did heat the Earth, energy would have been created....a violation of The Law of Conservation of Energy."..."It would also violate Electromagnetic Physics, Vector Mathematics etc. and ALL existing measurements." 1. Perhaps you've been confused by your use of the word 'heat' as a verb. Do you think that the temperature of the atmosphere rises when the atmosphere is 'heated' by the surface and the temperature of the surface rises when the surface is 'heated' by the atmosphere, but the temperature of either does not fall when it acts as the heat supply for the other? When radiation is absorbed by the atmsophere from the surface - if this happened in isolation, then aside from phase changes, the temperature of the surface would fall and the temperature of the atmosphere would rise. Energy is conserved. If the atmosphere radiates some energy that is absorbed by the surface, then if this happens in isolation, the temperature of the surface would rise, the temperature of the atmosphere would fall, and energy would be conserved. Of course, both, and other processes, are generally happening at the same time: Surface absorbs RSe from the sun and Rae from the atmosphere. Surface loses heat by Rea to the atmosphere, Res to space, and Cea (convection) to the atmosphere. The atmosphere absorbs RSa from the sun and Rea from the surface, and gains Cea from the surface, and loses energy by Rae to the surface and Ras to space. THESE EQUATIONS ARE BASED ON THE CONSERVATION OF ENERGY: Rate of energy gain by the surface = RSe + Rae - Res - Rea - Cea Rate of energy gain by the atmosphere = RSa + Rea + Cea - Ras In climatic equilibrium, the average of each rate of energy gain is zero. Where is energy being created or destroyed? ------- Oh, how tedious it is to explain anything to you, Gord.
  18. Patrick 027 453 The assessment is presented at my pdf linked from . This is entirely different from the usual Control Theory application in that it shows only that the feedback (as defined in Control Theory) from average global temperature can not be significantly positive. Wikipedia has fairly acceptable definitions for feedback as used in Global Warming and for feedback as used in Control Theory. In Control Theory, a positive feedback means that the trend will continue in whichever direction it is going (but at a declining rate because of the fourth power of absolute temperature). That is, if it is going down, it will keep going down approaching a new level asymptotically and if it is going up, it will keep going up approaching a new level asymptotically. The only way that the trend direction can change is if there is an external influence that is strong enough to overpower the feedback. Since in the paleo data the temperature trends are seen to change direction, it means that there had to be an external influence that was greater than the feedback and the feedback could not be significantly positive. Thus the climate sensitivity predicted by the GCMs should be the value that they calculate for zero net (Climate Science) feedback (1.2°C). I personally think that it will turn out to be less than 1.0. An explanation for the 20th century temperature rise was presented at 371 except I said Maunder Minimum (which refers to sunspot count) when I should have said Little Ice Age (which refers to temperature). The end result corroborated qualitatively the Grand Solar Maximum (which appears to have ended) that others talk about. The comparatively weak in effect on temperature GSM combined with a comparatively strong in effect on temperature PDO (they typically last about 30 years) uptrend to produce the temperature run up from about 1975 to about 2005. The last decade has seen no significant change in average global temperature. There are five agencies that report average global temperature. I averaged them all each year from 1998 through 2008 and the trend is flat. The trend from 2002 through 2008 is significantly down (1.88 °C/century) but it probably won’t stay that steep.
  19. "In climatic equilibrium, the average of each rate of energy gain is zero." I mean the average of one is zero and the average of the other is zero, not just the average of both.
  20. Dan - the climate models that simulate longer-term warming also produce some short term flat and cooling periods such as now. Variations in PDO, ENSO, AMO, etc (modes of internal (unforced) variability), could be contributing to these variations, as could some solar effects, though the evidence and physics backing such things, or non-TSI related solar effects, as major causes of the longer-term temperature increase is not at all as strong and solid as that which supports the known forcings in their relative proportions - anthropogenic greenhouse forcings being the biggest warming contribution and anthropogenic aerosols in total being the biggest cooling contribution, but with the total (net) forcing being positive (causing warming) and significant, and increasing. "In Control Theory, a positive feedback means that the trend will continue in whichever direction it is going (but at a declining rate because of the fourth power of absolute temperature)."..." That is, if it is going down, it will keep going down approaching a new level asymptotically and if it is going up, it will keep going up approaching a new level asymptotically." The second part of that actually fits with climatological terms; some change in forcing pushes the climate into a different state; feedbacks amplify or reduce the change, but there is some new equilibrium state the climate tends to approach. The first part, however, is different. Feedbacks in climate do not cause continuing change (in the long-term state, as opposed to weather, interannual variability, etc.) just by existing (they can cause continuing change by reacting to continuing change such as in internal variability). The equilibrium state the climate system finds is a new constant global average temperature - there will be fluctuations about that temperature but the longer term average is a constant. "The only way that the trend direction can change is if there is an external influence that is strong enough to overpower the feedback." A forcing shifts the equilibrium that the climate tends to approach; feedbacks modify that shift but still result in an equilibrium that the climate tends to approach. The long-term equilibrium is not itself a trend but a fixed state. Any forcing at any time can shift that equilibrium and if that forcing plus the feedbacks result in a shift that is in the opposite direction as some previous shift, the climate's tendency could reverse if the climate has already shifted far enough in response to a previous change. Climate sensitivity is the change in equilibrium climate per unit change in forcing and is thus modified by feedbacks. However, unforced changes always reverse due to negative feedbacks - unless their are multiple equilibria, or the climatic equilibrium is a strange attractor, etc, - but in those cases, the short term variability that results can still be encompassed within a full description of a yet longer-term equilibrium climate state. Maybe that is the distinction we need to go over. For example, water vapor: Water vapor is most likely a strong positive feedback (PS I may have been wrong earlier when I identified surface albedo via snow and ice changes as also being a quite strong positive feedback - it is strong regionally and is one of the more obviously observed, but it's contribution to the global average ... I'm not sure offhand). What is meant by that? The amount of water vapor in the atmosphere tends to approach an equilibrium value over a period of several days. The equilibrium value increases with increasing temperature. If there is a climate forcing - say, an increase in solar TSI or an increase in CO2 greenhouse forcing, as this starts to increase the temperature, the temperature will rise, tending to exponentially approach a new equilibrium temperature in which the change in temperature causes a change in LW radiative cooling that balances the imposed radiative forcing. The time it takes for this to occur is proportional to the heat capacity per unit area of the climate system (PS that varies depending on time scale but let's set that issue aside for now), and the equilibrium temperature increase per unit radiative forcing without feedbacks - because the radiative forcing is an energy supply rate per unit area, and the temperature change times the heat capacity per unit area is the amount of energy that needs to be gained in order to reach equilibrium. But as the temperature rises, the water vapor content also starts to rise, and this is a positive radiative feedback - it has a radiative 'forcing' that adds to the initial radiative forcing, so the total temperature change necessary to reach equilibrium increases. Interestingly, this also increases the time it takes to reach equilibrium, because the water vapor feedback to the change is initially zero and increases as the temperature increases. (With some calculus, I could show that the time constant to exponentially approach equilibrium is proportional to the climate sensitivity, which is the equilibrium change per unit externally imposed forcing). But what happens when the climate is at equilibrium? Remember, water vapor tends to be a function of temperature. Thus, an unforced change in water vapor decays to zero over a short time. There is some radiative effect that raises the temperature, but the time it takes for a significant temperature increase is too long compared to the time that water vapor itself changes in response to temperature. And if there is an unforced temperature change - well, that would be like having some forcing and then ending it. In other words, if CO2 is added to cause a temperature increase of 1 K and the water vapor feedback causes an additional increase of 1 K (not sure offhand if that is ther right proportion - this is just to illustrate the concept) - then what happens when the CO2 change is reversed? Well, there is a roughly 1 K decrease in temperature, and the water vapor feedback results in an additional 1 K decrease, returning the climate to where it was before the CO2 increase. Climate sensitivity could vary over temperature, but even if the water vapor feedback is stronger or weaker at the 2 K higher temperature, the senstivity will go through the same range on the way down as it did on the way up; the result is still a return to the initial value. So what if there were some unforced temperature increase of 2 K? Water vapor would increase, but it would not be strong enough to prevent the temperature from falling back - it would only delay the return to the initial temperature. In that sense, the climate, when not being forced to change, could be dominated by negative feedbacks - mainly the negative feedack of the increased radiative cooling in response to an increase in temperature. This is often not called a feedback because it is part of the climate response to forcings and other radiative feedbacks (you have to watch for context - sometimes feedbacks are described as having forcings, etc...). Of course, when the full complexity of climate is considered, there is a possibility of hysteresis loops, and things that do not respond fast to temperature over short periods of time may do so over longer periods of time. Externally-imposed forcings are boundary conditions. What can be approximated as a boundary condition in the short term may shift to being part of system behavior in the long term...
  21. "So what if there were some unforced temperature increase of 2 K? Water vapor would increase, but it would not be strong enough to prevent the temperature from falling back" To be more clear on the matter: Using the assumption of constant climate sensitivity for the sake of simplifying the argument: If a radiative forcing is able to sustain a 1 K increase without feedback, and the water vapor feedback increases the equilibrium change to 2 K, then that implies that the water vapor response to a 2 K increase is sufficient to sustain 1 K of the 2 K increase in temperature on it's own. Thus, if there is an unforced 2 K increase, the water vapor level will increase so as to support 1 K of that increase. Thust the temperature drops perhaps half as fast as it would without the water vapor feedback, but it drops because the water vapor feedback cannot sustain it fully. As the temperature drops, the water vapor drops back, so the temperature doesn't stop dropping as it approaches 1 K - by that point, the water vapor can only sustain 0.5 K, so the temperature keeps dropping. The temperature and water vapor eventually return (or approach) there initial values.
  22. Patrick 027 458 "Generally, almost all radiation that is absorbed is thermalized." I agree that some is. K&E doesn't show any. That is part of what is misleading. The rest of what is misleading is they show big numbers going from surface to clouds and clouds to surface. It misleads by showing all radiation going a long distance instead of being absorbed close to the surface by greenhouse gases.
  23. I am aware of the complexities of radiative energy 'model' was, as stated, simplified to demonstrate the principle that GG's simply affect the rate at which heat is transferred from the earth to space. Semantics possibly, but it is important we all ( and those who come here seeking clarification of a comlex subject) understand the terms expressions and concepts used.
  24. RE 466 Dan - "I agree that some is. K&E doesn't show any. " When a radiant flux is absorbed, it is assumed to be mostly thermalized; K&E implies thermalization whereever they show absorption. It is not misleading. In as far as the fluxes going long distances - this is not a diagram that is meant to be to scale - it is a schematic diagram. (that should be readily apparent - the atmosphere is shown as a layer that is detached from the surface, which appears flat. The solar flux is shown bending and bouncing off of things in an unrealistic manner. But it is correct (or approximately correct) for what it is.) It is only misleading if you misinterpret it.
  25. Patrick - Re: Your Post #459 Right from the NASA website: The Greenhouse Effect "Scientists have long known that the presence of an atmosphere keeps the surface of the planet warmer than it would be without an atmosphere. In fact, without an atmosphere, the surface of the earth would be about 30 degrees Celsius cooler than it is now!" ------------------ The Earth with an atmosphere has an albedo of 0.3, without an atmosphere it will be less than 0.3. I chose an albedo of zero and like I have I have REPEATELY said this number is as valid as the 0.3 assumption in the calculation. --------------- Patrick said... "...but I would think the people at NASA are at least as knowledgable on the subject as I am..." Obviously you have "delusions of grandeur" considering your total lack of scientific knowledge and your complete inability to understand what "NO ATMOSPHERE" means. It is very, very tedious explaining things to you and backing up my statements with links. Your posts are all rife with obvious errors and hilarious opinions that are totally unsupported. In short, your posts show a total ignorance of the subjects you babble about.

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