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Chris G at 00:51 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
Regarding #27(2), When a water molecule evaporates from, say, the ocean, energy is transferred from the ocean to the atmosphere. When the molecule condenses back into rain, and precipitates, energy is transferred back. The net effect is zero. How does this contribute to global cooling? (At what altitude (range) does most precipitation form and is that high enough to significantly affect how readily it is radiated out?) -
Ned at 00:45 AM on 1 July 2010Perth forum on climate change: all the gory details
chriscanaris, the report is thoroughly German in other ways, too. The table of contents lists sections hierarchically up to four layers deep. The table of contents & list of figures etc. runs on for 35 pages! -
JMurphy at 00:39 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
NickD wrote : "As a member of the general public, I can assure you I come to this site often, refer other members of the general public to this site as a great resource for laypersons to understand scientific concepts, and I appreciate the explanations provided by John Cook, Kevin Judd, Doug Bostrom, and many others." Hear, hear and seconded. I would also like to add mention in the dispatches to Marcus, Ned, David Grocott and ChrisG, who always have detailed and referenced answers to all the strange theories and assertions that some people post on this site, especially recently. I admire the forbearance of you all... -
Ken Lambert at 00:37 AM on 1 July 2010Astronomical cycles
Peter Hogarth #111 I used this chart: http://sealevel.colorado.edu/current/sl_ib_ns_global.jpg which is IPB corrected and seasonal signals removed. Running a linear fit between 2003 and 2009 gives about 2.1mm/year and 2002 to 2010 gives about 2.4mm/yr. It is clear that the 3.0 +/- 0.4mm/year linear trendline is not a good match for the 2002 - 2009 period of Jason 1. The 60 day smoothed line is above the trend for the 2002-2007 period and crosses below it for 2007-2010, with an uptick in the last year or so apparently due to Jason 2. This is clearly a flatter trend for the Jason 1 perod than the 17 year trend line. It sounds like splitting hairs, but according to Dr Trenberth's Table 1 (Aug09 paper 'Tracking Earth's global energy') the total land ice loss accounts for about 2.0mm/year of SLR but only 2-3E20 Joules of heat is required to melt it, while every 0.4 - 1.2mm of thermosteric rise equals about 20-95E20 Joules of increased OHC. So finding more steric rise is the only way to get closer to an energy balance; and more ice melt rise rapidly worsens this energy budget shortfall. Problem is you can't have increased glacier melts and a flattening SLR without reducing the steric component consistent with a flat OHC in the top 700m; and have a TOA energy imbalance of 145E20 Joules/year at the same time. It is indeed a travesty of conflicting data. -
RickG at 00:37 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
RSVP, I assume your water molecules get replaced by other water molecules such that the overall amount of water vapor remains relatively constant (on the average). So water vapor remains relatively constant and global temperature keeps rising? Seems to me you just ruled out water vapor as a cause for GW. -
Chris G at 00:36 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
Hopscotching comments here. Regarding #25, OK, so waste heat has to "...go through the CO2 gauntlet..." the same as the energy from the sun after the earth has, in effect, converted SW to LW. The amount of energy in has to be on long-term balance with energy out; so, how much energy does the earth receive from the sun compared to how much industry puts out? The sun's energy is orders of magnitude larger. Yet, somehow waste heat has a larger impact? -
KR at 00:29 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
RSVP - while all sources of heat do feed into the equation, a simple order of magnitude calculation indicates that waste industrial heat accounts for one part in 10,000 of global warming compared to radiative imbalances. So yes, industrial heat does add to global heating, but not enough to matter - not even enough to show up over noise/chaotic daily weather/measurement error/phase of the moon (Joking on that last one, joking! Although I believe lunar irradiance does have some effect...). -
RSVP at 00:24 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
Marcus "This potency is further amplified by the fact that the resident lifetime of a single CO2 molecule-in the atmosphere-is much, much longer than that of a single molecule of water. " Two things. 1) I think it was Shrek, not the donkey. So I will admit making a mistake on that count. 2) I assume your water molecules get replaced by other water molecules such that the overall amount of water vapor remains relatively constant (on the average). If so, not sure why this matters? Not only that, it just happens to take energy for this to happen, which is a plus for global cooling. -
chris1204 at 00:21 AM on 1 July 2010Perth forum on climate change: all the gory details
I've just opened the previous post tonight and was very pleasantly surprised to find Volker's study which I've just downloaded. Now that's just so thoroughly German (in the best sense of the word) to address the very question I thought nobody seemed to be asking (the carbon cost of making a transition to renewables). I'll be reading it with great interest. Thank you John and Volker :-) -
Chris G at 00:21 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
Not to make it 'pick on RSVP' day. But... "...any "transparent" gas..." "...water vapor is transparent and reflects light depending on temperature and pressure..." OK, I might not be getting what you are meaning here, but 'transparent' is a poor term for gasses. Mainly because their transparency is function of the wavelength of the light, not temperature and pressure, btw. Water vapor and CO2 are transparent at some wavelengths and not at others. That's kind of the whole reason why there is a greenhouse effect. "...and non linear. " Right, we know that; it is a log function. (Unless you are talking about how water vapor condenses and precipitates, but that is the part that isn't clear.) "...waste heat is accumulating." Hmm, if the absorption and emission of IR (heat), and hence retention, is negligibly affected by an increase in an IR absorbing gas, like H2O and CO2, what keeps the waste heat from radiating off into space? The only thing that would prevent that would be a greenhouse effect stronger than AGW needs, yet you are arguing that there isn't a greenhouse effect strong enough to let AGW happen. -
RSVP at 00:16 AM on 1 July 2010What is Global Warming and the Greenhouse Effect?
Marcus "your "it's waste heat" hypothesis falls flat on its face-" Not so fast... One thing you can be sure of is that waste heat is entering the atmosphere. (If this were not true, my car's engine would overheat.) And its not just heating the CO2. Its heating all gasses, even those that do not emit IR so well (as per AGW). Similar problems exist for thermal pollution entering our rivers and the ocean. After that, this same heat has to go through the CO2 gauntlet upward, which you adamantly profess has made heat escaping more difficult. Just as can happen with commuter traffic, when the throughput increases, you get a traffic jam. This happens even when the same number of lanes are free. Just imagine if a lane gets closed (this would be the CO2 factor). So, it may be a combination of both effects. -
Arkadiusz Semczyszak at 23:52 PM on 30 June 2010Perth forum on climate change: all the gory details
@Marcus 280 ppmv. Easily accessible (due to warming) and natural sources, eg : detritus of soil - estimated age: at least 1000 - a maximum of 10,000 years (the majority in the polar area, which is the fastest warm feeling) is still currently available quantity is estimated at 600 - 800 Gt C. -
Marcus at 23:16 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Oh, & "imagining" CO2 has no impact is very different from it actually *having* no impact. We know-& can directly measure-the impact CO2 has on outgoing long-wave radiation, & even its natural (non-enhanced) effects totally dwarf any known impacts of thermal pollution by several orders of magnitude. -
Ned at 23:15 PM on 30 June 2010Temp record is unreliable
It seems to me that a lot of the questions people ask about the surface temperature data have been answered, at least in part, by the various "independent" (i.e., non-official) reconstruction tools that have been developed over the past six months. For example, all of the following questions have been addressed: (1) Can the "official" temperature records (GISSTEMP, HADCRU, NCDC) be replicated? [Yes] (2) Does the GHCN adjustment process have a large effect on the surface temperature trend? [Generally no] (3) Does the decrease in high latitude (or high altitude, or rural) stations have a large effect on the temperature trend? [No] (4) Does the location of stations at airports have a large effect on the the temperature trend? [No] (5) Does the overall decline in station numbers have an effect? Don't you need thousands or tens of thousands of stations to compute an accurate global temperature trend? [No, it can actually be done with fewer than 100 stations] There are probably other questions that I'm forgetting. Anyway, here are some handy links to tools that people have put together for do-it-yourself global temperature reconstruction. Many (but not all) of these are open-source, and many are very flexible, so that you can create reconstructions using different combinations of stations to test particular hypotheses. * Clear Climate Code (exact replication of GISSTEMP using Python). * Ron Broberg's blog "The Whiteboard" (replication of GISSTEMP and CRUTEMP) * Nick Stokes's GHCN processor * GHCN Processor by Joseph at Residual Analysis * Zeke Hausfather's temperature reconstructions (no single link, but see here and here) * Tamino * RomanM and Jeff Id * Chad at "Trees for the Forest" If there are others that I'm missing, maybe someone could add links in this thread. -
Marcus at 23:14 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
OK RSVP, on point (1)-have a look at the above posts-aside from you & Karl, everything here *does* agree with me-so its a pretty fair assumption. This has nothing to do with belonging to a "club", but everything to do with having more than a basic grasp of scientific concepts. (2) if recent warming were the result of accumulating waste heat then (a) there would be some correlation between rising industrialization & rising temperatures (we don't, btw); (b) we'd expect to see the most rapid warming in industrial sites, with non-industrial sites warming less rapidly, if at all (in fact, many wilderness sites-like the Arctic & Antarctic-are warming at a significantly faster rate than urban & industrial sites) & (c) we'd be able to account for every Joule of that energy to *prove* that it was accumulated waste heat. As I've said before, waste heat accounts for as little as 0.01% of all the energy the planet receives (about 13 Terra-watts), as compared to the roughly 180 Peta-watts worth of solar radiation that enters the system from the sun. So, on all 3 of these counts, your "it's waste heat" hypothesis falls flat on its face-& no amount of repeating a dud hypothesis will suddenly make it good. -
RickG at 23:08 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
RSVP, You seem to be ignoring that water vapor is a feedback, not a forcing, as well as the well known and understood physics of CO2. -
RSVP at 22:57 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Marcus "What I love is how RSVP can claim that CO2 is too "small" to have an impact on the climate, yet he still holds to the notion that industrial heat-which accounts for less than 0.1%..." Two things (as the donkey on Shrek said...) 1) It appears you are directing your comment to readers that you assume agree with you. Are these club members? 2) Just imagine if CO2 was having zero impact. That then would be saying a lot about how much waste heat is accumulating. Remember integration from college? -
Marcus at 22:44 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
What I love is how RSVP can claim that CO2 is too "small" to have an impact on the climate, yet he still holds to the notion that industrial heat-which accounts for less than 0.1% of all the energy this planet receives-is to blame. Talk about holding two contradictory views at the exact same time. A good analogy for CO2 might be a biological toxin like Pertussis or Botulinus. An average human being weighs more than 50kg, yet doses measured in milligrams could prove potentially fatal. There are other toxins which are even more deadly, in smaller doses. Its not the quantity that matters, but the ability to effect the system that matters. CO2, NO2 & CH4 are all *trace* elements, yet they're all exceptionally good at absorbing outgoing IR radiation. This means that you don't need much of them for them to start having a malign impact-just as you don't need much of a compound that blocks neurotransmitter function to kill a person! -
NickD at 22:34 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
RSVP at 17:17 PM on 30 June, 2010 says: "And I doubt that the "general public" you are referring to come to this site, or even have much interest in global warming theories." As a member of the general public, I can assure you I come to this site often, refer other members of the general public to this site as a great resource for laypersons to understand scientific concepts, and I appreciate the explanations provided by John Cook, Kevin Judd, Doug Bostrom, and many others. -
Marcus at 22:32 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
I really think that people like John D & RSVP need a sense of perspective. On the one hand you have water vapor, making up 3% of the Earth's atmosphere & accounting for, on average, roughly 65% of the *natural* Greenhouse Effect. Then you have CO2, making up less than 0.03% of the Earth's atmosphere (pre-industrial), yet accounting for almost 20%-on average-of the *natural* Greenhouse Effect. This suggests that, on a parts per million basis, CO2 is about a 20 times more potent greenhouse gas than water vapor. This potency is further amplified by the fact that the resident lifetime of a single CO2 molecule-in the atmosphere-is much, much longer than that of a single molecule of water. Yet we're to believe that artificially ramping up the levels of CO2 in our atmosphere will have only a negligible impact on our climate-in spite of the fact that we've had a greater than 0.6 degree warming in the space of only 60 years-which just happens to coincide with a significant rise in anthropogenic CO2 emissions & a decline in solar activity. Some people appear to believe that we're a bunch of mugs! -
Ned at 22:29 PM on 30 June 2010Temp record is unreliable
Berényi Péter, you're part way there. Handling the US and the rest of the world separately is a good start, and for a simple order-of-magnitude guesstimate it might be enough. But as with everything in statistics you need to understand your assumptions. Treating the rest of the world as homogeneous will not yield an unbiased estimate of the global mean adjustment unless either (a) the stations are distributed approximately uniformly in space or time, or else (b) the expected value of the adjustment for station X in year Y is independent of that station's location. (For that matter, this also applies to treating the US as homogeneous). We know that (a) is untrue. So the question is whether (b) is true, or close enough to true that you can live with the resulting bias. (As an aside, the existence of nonstationarity in the expected value of the adjustment is not evidence of "tampering" ... there are many valid reasons why stations in country 1 or state 1 would require different types of adjustments than stations in country 2 or state 2). Again, you can just assume that the impact of any spatial heterogeneity will be small, and ignore the bias in your calculations. That's essentially what you did above. Alternatively, you can weight the data spatially, e.g. by gridding, and remove the problem. Does this help? -
David Grocott at 22:22 PM on 30 June 2010What causes the tropospheric hot spot?
Baa Humbug, You've made a few misleading statements there.Regarding the hot spot being a "signature" of GHG warming, I must respectfully disagree. It's not just the IPCC presenting a chart which clearly shows the distinctive signature of GHG warming...
...as modelled from 1890 to 1999. That's a rather important caveat. It is not a 'distinctive signature' of AGW at all. Please see my previous postings on this, at is a very important point. If it were a unique 'signature' of AGW, and you chose to believe it was absent, then it would be plausible to say that current warming is not being caused by human activity. But as it is not a unique signature, if you choose to believe it is absent, then that leads to the obvious conclusion that warming is not occuring, period. This is a much more difficult argument to make. This is the last time I will outline this distinction, as I'm starting to get bored of the sound of my own voice. The four images which you have provided reflect the same reality as the image I provided at #48, labelled 'For 2xCO2'. They demonstrate that a doubling of CO2 creates a tropospheric hotspot. As my other image at #48 shows, a 2% increase in solar activity (a forcing in the same order of magnitude as a doubling of ACO2) creates a similiar tropospheric hot spot. The comparison is the important bit, not the accepted fact that a doubling of CO2 should cause a tropospheric hot spot, as your images show.The IPCC quote you provided is unequivocal IMHO, where it states, "The combination of a warming troposphere and a cooling stratosphere has likely led to an increase in the height of the tropopause and model-data comparisons show that greenhouse gases and stratospheric ozone changes are likely largely responsible". So if GHG's are largely responsible, then GHG's are the main cause of the distinct hot spot, which as the 6 graph chart shows in C and F, is much more powerful than other forcings, man made or natural (a,b,d,e)
As 'e' pointed out at #57:the tropospheric hotspot is a distinct concept from stratospheric cooling + tropospheric warming. The tropospheric hotspot is a greater warming of the troposphere in lower latitudes relative to higher latitudes. This is a prediction that follows from any warming, not just from CO2. Stratospheric cooling is the cooling of the stratosphere while the troposphere warms across all latitudes. This prediction is unique to warming from GHG's.
I've also pointed out a number of times that a warming troposphere (distinct from a specific hot spot) and a cooling stratosphere, is a unique signature of AGW. The existence of both of these phenomena are supported by observational data. Although your logic breaks down, you are right in saying that (assuming we accept the IPCC's assertion that human activity is causing the majority of observed global warming) "GHG's are [or rather 'should be'] the main cause of the [current] distinct hot spot". As I've pointed out,if (big if) you conclude that the tropospheric hot spot does not exist, then you must argue against the observation of global warming from any source, as opposed to just AGW. There's actually very little in the IPCC document about the tropospheric hot spot - presumably as a result of the fact that it proves very little beyond the fact that the models are accurate (or not) in their predictions of atmospheric zonal temperature responses to warming (of any kind). The small, oft-quoted section that there is, is fairly misleading. Much greater 'air-time' is given to the warming troposphere/cooling stratosphere phenomonen, which is undeniably being observed, and is a signature unique to AGW. The brief section of the IPCC document which concerns us...The simulated responses to natural forcing are distinct from those due to the anthropogenic forcings described above. Solar forcing results in a general warming of the atmosphere (Figure 9.1a) with a pattern of surface warming that is similar to that expected from greenhouse gas warming, but in contrast to the response to greenhouse warming, the simulated solar-forced warming extends throughout the atmosphere.
...doesn't refer to the tropospheric hot spot at all, but rather to the fact that solar forcing results in a warming of the whole atmosphere, where as AGW forcing results in a warming of the troposphere and a cooling of the startosphere. The fact that it links to a picture of a number of charts showing zonal mean atmospheric temperature change from 1890 to 1999 (which happen to show the hot spot created by greenhouse gases during that period) is neither here nor there. This is a matter which has been mistakenly leapt on by 'sceptics', not least Jo Nova, who appear to consider it the lynch pin of AGW theory. Like you I look forward to some more definitive papers on the matter. -
Marcus at 22:17 PM on 30 June 2010Perth forum on climate change: all the gory details
Maybe John, its because you were trying to drag the topic back to CO2 as a plant food again- & again without a skerrick of proof to back you up. This comment will probably be deleted, but I hope you see it before it does, so you understand why your post was OFF-TOPIC, wheras mine at 16:11 continues the already existing theme for this thread-namely how to respond to denialists like yourself. -
sleepership at 21:57 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
The Science of Global warming---the Greenhouse condition is over 100 years old- and is not 'exotic' but basic science. The science is solid and basic physics. The doubt comes from what some believe is the human imprint to warming- which actually has been very strong- increased industrialization shows the burning of fossil fuels to have increased CO2 levels to nearly 400ppm. -
Berényi Péter at 21:55 PM on 30 June 2010Temp record is unreliable
#78 Ned at 01:39 AM on 30 June, 2010 Contrary to what BP claims, it's really important to use some form of spatial weighting (e.g., gridding) when doing this, because the stations are not uniformly distributed. OK, I have understood what's going on. In a sense you are right, but for a different reason what you think you are right for. You do not have to do any gridwork, just treat the US and the rest of the world separately. 1. Until about 2005 the USHCN used to be heavily overrepresented in GHCN (since then it is getting underrepresented, 4.16% in 2010). 2. Between about 1992 and 2005 up to 90% of GHCN readings came from USHCN, before that time it was 20-40%. 3. Since 2006 there is no adjustment in USHCN and since 1989 for the rest of the world. 4. Adjustments for USHCN are much bigger than for the rest of the world. They also follow a different pattern. It looks like two different adjustment procedures were applied to the US data and the rest of the world and the results were only put together after that. US land area is 9,158,960 km2, world is 148,940,000 km2, therefore the US has 6.1% of land. If the world is divided into two "regions": the US and the rest and area weighted average is calculated, trend in global adjustment is 0.1°C/century for 1900-2010 (the same figure is 0.39°C/century for USHCN). Unfortunately this peculiar feature of GHCN is undocumented. -
Riccardo at 21:40 PM on 30 June 2010What causes the tropospheric hot spot?
The quoted paragraph from the IPCC refers to troposphere warming AND stratosphere cooling and of GHG AND ozone. The graph you show are for doubling CO2 not for what we should currently observe. -
CBDunkerson at 21:23 PM on 30 June 2010September 2010 Arctic Ice Extent Handicapping Via ARCUS
There is a very good new article on Cryosat-2 showing some of the first data released here. The Arctic scan included in the article shows situations where previous instrumentation (e.g. PIPS) would have reported a large area of thick ice for what was really just a few large chunks. They're still calibrating data (after moving the satellite into a new orbit), but expect to start releasing results in a few months. Thus they should be able to tell us what the minimum ice volume for this year was, but it may be a couple of months after the event. -
CBDunkerson at 21:14 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
RSVP #15, so everything in the article above is true... but you are arguing that the AMOUNT of warming may be negligible. Which seems like arguing for the sake of arguing since the article states that this very issue, how much warming is likely to occur, will be covered in a subsequent installment. So leave that aside for when it's actually considered and take this article for what it is... a simple explanation of greenhouse warming which is every bit as "accurate, absolute, and true" as Newton's third law of motion. A point which only need be made because 'skeptics' jump up to object whenever it is... falsely suggesting that there is some doubt on the issue. -
Baa Humbug at 20:46 PM on 30 June 2010What causes the tropospheric hot spot?
Thnx David Yes I also must agree that the results are a little unsatisfying. From the links in the original article, Titchner et al says (for instance) "our analysis using realistic validation experiments is unable to discount or confirm the presence of a tropical tropospheric lapse rate discrepancy between the radiosonde observations and climate model expectations". And Sherwood says "the agreement would improve if one were to remove the deep tropical stations whose behavior is inconsistent with the rest of the network. This reinforces similar previous findings of consistent trends (Fu et al. 2004; Mears and Wentz 2005; Sherwood et al. 2005; Vinnikov et al. 2006) but remains unsatisfying until errors are further reduced". Regarding the hot spot being a "signature" of GHG warming, I must respectfully disagree. It's not just the IPCC presenting a chart which clearly shows the distinctive signature of GHG warming (chart C in the article), four other organizations show very similar signature. (I hope I can do the image thing correctly)
Zonally-averaged distributions of predicted temperature change in ºK at CO2 doubling (2xCO2 – control), as a function of latitude and pressure level, for four general-circulation models (Lee et al., 2007).
Eyeballing each of these, one would be excused for concluding a tropospheric warming of up to 3 times that of the surface.
The IPCC quote you provided is unequivocal IMHO, where it states, "The combination of a warming troposphere and a cooling stratosphere has likely led to an increase in the height of the tropopause and model-data comparisons show that greenhouse gases and stratospheric ozone changes are likely largely responsible".
So if GHG's are largely responsible, then GHG's are the main cause of the distinct hot spot, which as the 6 graph chart shows in C and F, is much more powerful than other forcings, man made or natural (a,b,d,e)
So I guess where I am at this moment is that a number of organizations including the IPCC have taken the trouble to distinguish GHG influence on the troposphere at the tropics. Why they chose to do that is theirs to answer.
I await eagerly, some definitive papers on the unsatisfying troposphere t trends.
-
RSVP at 20:27 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
doug_bostrom, werafa, et all "For every action, there is an equal and opposite reaction." That was Newton talking about inelastic collisions between moving bodies. This is accurate, absolute, and true. How does this play out when one mass is that of the Earth, and another, a small rock landing on say a hard cement patio? Does the Earth "react"? Not a whole lot. The issue is not whether CO2 aborbs or emits IR. The issue is whether the amount of CO2 is making any measurable difference in climate change. If my assertions sound confusing, it is only because the dynamics are complex. For instance, water vapor is transparent and reflects light depending on temperature and pressure. This means that modeling the effects of just water vapor on its own is complex and non linear. -
David Grocott at 19:25 PM on 30 June 2010What causes the tropospheric hot spot?
Baa Humbug @ #53 No problem. You say "Between satellites and radisondes this amount of warming should have been detected. It hasn't been." That is your view, and I can only refer you back to the article above and John's original article addressing Nova's claims. John points out that the amount of expected warming (or near to it) has been detected by weather balloons (Titchner 2009, Sherwood 2008, Haimberger 2008), wind shear measurements (Allen 2008), and the UWA satellite data. And as Prof. John Christy points out, the discrepancy between the UAH satellite observations and the models is most likely a result of measurement uncertainty. Regarding the 3 possible options for explaining the existing uncertainty, the IPCC does argue for one:Since the TAR, further evidence has accumulated that there has been a significant anthropogenic influence on free atmosphere temperature since widespread measurements became available from radiosondes in the late 1950s. The influence of greenhouse gases on tropospheric temperatures has been detected, as has the influence of stratospheric ozone depletion on stratospheric temperatures. The combination of a warming troposphere and a cooling stratosphere has likely led to an increase in the height of the tropopause and model-data comparisons show that greenhouse gases and stratospheric ozone changes are likely largely responsible (Figure 9.14). Whereas, on monthly and annual time scales, variations of temperature in the tropics at the surface are amplified aloft in both the MMD simulations and observations by consistent amounts, on longer time scales, simulations of differential tropical warming rates between the surface and the free atmosphere are inconsistent with some observational records. One possible explanation for the discrepancies on multi-annual but not shorter time scales is that amplification effects are controlled by different physical mechanisms, but a more probable explanation is that some observational records are contaminated by errors that affect their long-term trends.
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-4-5.html As you can see the IPCC raise the possibility that the models are incomplete (option 2), but suggests it is more likely that the discrepancies are a result of errors in the observational record (option 3). I'm inclined to agree with John when he says "Looking at all this evidence, the conclusion is, well, a little unsatisfying". However, if you take the view that the hot spot is absent, and you don't agree with the IPCC that its perceived absence is a result of measurement uncertainty (or possibly problems with the models), then you must take the view that the temperature record is unreliable. Something Roy Spencer (for one) disagrees with. When making judgements (which you sometimes must) it's important to look at the whole picture, and make the most reasoned call. In my view the most obvious call is that the contradictory evidence is a result of measurement uncertainty; any other judgements would involve larger leaps of logic. Regarding your final point:Also, as much as I appreciate the charts you have posted, the AR4 makes it clear that the sun has had negligable affect on climate in the 2nd half of the 20thC, therefore, if a hot spot was to be detected, (along with a cooling stratosphere) it can only be a response to CO2 forcing, no?
Correct - if you first accept the IPCC's assertion that human activity is largely responsible for the rise in global temperatures - which I think is where all this confusion about the hot spot being a signature of AGW comes in. The IPCC, as you state, makes clear that anthropogenic forcings are the primary contemporary climate forcing. Therefore, if a hot spot is detected then it would be evidence of warming, which by the IPCC's definition must have been caused by human activity. Finding the hot spot doesn't prove that humans have caused global warming, in fact it doesn't prove anything, but it does show that the models are correct in what they anticipate the effects of any warming to be, and in the process strengthen the case that warming is occuring. The fact that the troposphere is warming and the stratosphere is cooling (as shown by observational data) does provide evidence that it is humans that are causing the current warming, as opposed to the sun's activities. -
werafa at 18:25 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Please also remember who we wish to inform and influence. Scientists regularly fail to engage members of the public precisely because they insist on absolute precision, but loose accuracy and effect. This post, for all its generalisations, explains a concept in a way that my mum could understand. That is vital -
John Chapman at 18:24 PM on 30 June 2010On the reliability of the U.S. Surface Temperature Record
In cold climates those reverse-cyle ACs actually blow out cold air, so maybe that's why the poor-sited readings are often lower? -
werafa at 18:19 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Carbon dioxide is part of the greenhouse effect, and this does keep the globe warm. Without the greenhouse effect, life would probably not exist. does increasing the amount of carbon dioxide enhance the warming effect? The evidence says yes it does, and this is the basis of the Global Warming theory. Note: It is not yet (and probably never will be) possible to prove this with absolute statistical certainty, but would you go on 100 plane flights if you only have a 95% chance of surviving each flight? -
John Chapman at 18:02 PM on 30 June 2010Ocean acidification
At a talk last night David Archibald finished by showing a picture of some coral and CO2 bubbling past. Well they were bubbles, but he said it was CO2 and the coral looked dead to me and he said there were fish swimming around though I couldn't see any in the photo. What do you make of his claim that coral is resililent to acidification? -
JMurphy at 17:50 PM on 30 June 2010Hockey stick is broken
doug_bostrom wrote : "Sorry, I'm not biting. Anybody else up for a pointless argument?" I would direct marty to NOAA Paleoclimatology (hope they're not considered biased and part of the big conspiracy), where he can check out data from boreholes, pollen, insects, etc. But, marty, why do you think bristlecone pine data is 'misleading' ? -
Doug Bostrom at 17:40 PM on 30 June 2010Sea level rise is exaggerated
Ad hominem, Daniel? Yes, some things concern attributes of individual persons, specifically in this case what they know and don't know. Are you a geologist with an advanced degree specialized in paleochronology, Daniel? Have you spent a significant portion of your life learning how to tease dating information out of stratigraphic sequences? If you can honestly answer "yes" then my comparison of your abilities with regard to paleochronologies with those of Donnelly is less relevant. If you can only answer "no" then your assertion that Donnnelly's paper is "pure junk" is notably arrogant and makes your lack of qualifications a matter of complete relevance. If you answer "no" you are an amateur without a professional record casting rather nasty aspersions on the work of a professional with an extensive research track record in the subject you purport to be able to judge. There's entirely too much of this sort of thing going around, it's debasing to everybody concerned. You seem upset that you're not free to make whatever remarks you please here. I suggest that you've developed some poor habits by frequenting places where debased discussion is tolerated. Your choice of the term "pure junk" effectively made you part of the subject we're discussing because naturally anybody reading that remark is going to immediately wonder, "who says that and why should I believe him?" As you can tell, your language certainly got my attention. By your language you chose yourself as a topic, Daniel. Please don't complain to me about your choice. -
johnd at 17:38 PM on 30 June 2010Perth forum on climate change: all the gory details
Marcus at 16:11 PM, my response to youir post has been deleted, but your post remains. Can whoever moderated the post explain. If my response was OT, so is the post I responded to. What has happened to the courtesy normally extended if posts are tending off topic? -
Doug Bostrom at 17:21 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
RSVP, if you're going to quibble with Kevin you'll need to have your facts straight. For starters, you're wrong about how clouds interact with IR. By expressing your confusion as assertions you're spreading your confusion elsewhere. Please don't. -
daniel at 17:19 PM on 30 June 2010Sea level rise is exaggerated
Doug you do a lot of commenting on this website so I don't really know how cosy you are with the authors. I have been absent because my comments have been deemed inappropriate by a rather draconian comments policy. I will assume you know little about that but I am suspicious since you continued to argue with me and seemed to address some of the issues I was raising in those comments. I will address your recent comments soon. I have only skimmed over them now. I would like to say that this comments policy is not endearing to the authors of the website. If you deem your opponents comments as uncivilised, off topic, whacky or inappropriate then you can just casually reply saying as much and allow them to discredit themselves as they rant some more. Only truly foul language should be deleted. Explain to me doug why it is that you can use ad hominem arguments against my credibility by saying that I'm not a climate expert and therefore have nothing to say in regards to the quality of work coming from those fields? It really doesn't look good for you guys. -
RSVP at 17:17 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
<> Even the simplest of explanations should be consistent with reality. And I doubt that the "general public" you are referring to come to this site, or even have much interest in global warming theories. -
Doug Bostrom at 17:10 PM on 30 June 2010Hockey stick is broken
I smell a rhetorical question. Marty knows enough about temperature reconstructions to speak of "misleading bristlecone pine data" but wants help finding a reconstruction without 'em. Sorry, I'm not biting. Anybody else up for a pointless argument? -
RSVP at 17:10 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
To Kevin Judd The style of this writing is very good in that it uses simple and straightforward language, however... When seen from above, clouds appear white because they reflect a good part of the visible light spectrum. Clouds appear black underneath, because there is not a lot of visible light emanating from the Earth's surface. If clouds keep heat in as you say, (and I assume you mean locally below the clouds), they must be doing so generally only for IR emanating from the warmed air and surface below the cloud. In addition, they are not absorbing most of this heat but rather reflecting it. This is very different from my understanding of the AGW model which focussed on the heat that CO2 itself is absorbs. When in fact the word "greenhouse" seems to be more applicable to cloud cover as compared to any "transparent" gas, the analogy of CO2 with clouds seems to break down heartily because of the effects of an abrupt reflective boundary between a cloud and non-clouded air; a boundary that does not exist for CO2. Another way to see this would be to assume the Earth were covered completely in clean fog, and ask, would it be cooler or warmer? Or the complement of this question, which would be, "what conditions lead to fog?" -
villabolo at 17:06 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
#1) Karl_from_Wylie at 14:21 PM on 30 June, 2010 "Article presents a simplistic argument. Nature has more variablity, and more inputs than simply an increase in Carbon Dioxide." ********************************************************************************************** Karl, I believe this post was intended for the general public and is thus kept somewhat simple on purpose. It's not that simplistic, however, when you take note of the fact that you're referring to "Nature". That implies previous events of "Natural Global Warming". However, the focus of this post is about "Man Made Global Warming" in which Carbon Dioxide is the main cause. -
marty at 16:47 PM on 30 June 2010Hockey stick is broken
Can anyone tell me if there are temperature reconstructions that specificall avoid the use of the misleading bristlecone pine data? Cheers -
Doug Bostrom at 16:37 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Actually John there is much mentioned of water vapor in anthropogenic climate change research. In short, water vapor is being supplied to the atmosphere in increasing quantities as things warm up and more water vapor makes the problem of warming worse. Here are a couple of helpful articles: Water vapor and global warming Attribution of observed surface humidity changes to human influence I believe there is a new paper being prepared for publication in the coming months that examines cosmic rays and cloud formation. Indeed, some things never change. Geese migrate, papers on cosmic rays and clouds are prepared for publication. -
Phila at 16:35 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Whilst much is made of how high CO2 levels may rise to, there seems to be little mention made of how much the water vapour levels will rise and whether there is an ultimate limit. Little mention where? Climate scientists have addressed this issue at length, repeatedly. See Water vapor is the most powerful greenhouse gas, just for starters. It's one thing to disagree with a specific scientific arguments on water vapor, but to act as though it's being downplayed or ignored is kind of absurd, especially for a longtime commenter on this site. In my experience, there are in fact very few "skeptical" arguments and very few uncertainties of which "little mention" has been made by climate scientists. -
Marcus at 16:11 PM on 30 June 2010Perth forum on climate change: all the gory details
My counter to the "CO2 is just the result of the MWP lag" would be this-"where does all the excess CO2 come from?" If you look at the Ice Cores that show the various Milankovitch Cycle driven Glacial & Inter-glacial periods, you can see that CO2 concentrations rarely get much above 260ppm-& *never* get above 300ppm-in spite of temperatures rising by around a couple of degrees above those at any period in the Holocene. All available Paleo-climate data shows that temperatures in the MWP never reached the heights of previous Inter-Glacial periods. So, if this CO2 is from natural sources only, then why did much warmer periods not produce CO2 concentrations of around 400ppm or more? My understanding is that its because ca. 280ppm is the total amount of CO2 available in the Quaternary Era Atmosphere & Carbon Sinks combined. Therefore the only other source for this CO2 (aside from *massive* volcanism) must be coming from fossil fuels formed when CO2 levels were at levels of 1000ppm or above. My other counter would be "show me the 14-C fingerprint that proves the CO2 from natural sinks". -
johnd at 16:03 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Comparing CO2 to clouds is wrong. Clouds are not a greenhouse gas. Water vapour is however, and it is always present. Whilst much is made of how high CO2 levels may rise to, there seems to be little mention made of how much the water vapour levels will rise and whether there is an ultimate limit. Clouds are also always present providing between 64% and 69% coverage globally. Clouds provide an overall nett cooling effect for the planet. I believe there is a new paper being prepared for publication in the coming months that examines cosmic rays and cloud formation. -
ScaredAmoeba at 15:49 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Karl_from_WylieBias. Increase in Carbon dioxide does not assure Global Warming. There are more variables to the equation.
It is noted that you provided not one shred of evidence for your assertion. You overlooked this:Of course, this is a simplified explanation of global warming, ...
Which rather demolishes the entire point of your post. Perhaps you should learn to read more carefully. Skeptical Science has debunked numerous claims made by a well funded denial industry. Smoke, Mirrors & Hot Air: How ExxonMobil Uses Big Tobacco's Tactics to Manufacture Uncertainty on Climate Science Koch Industries Secretly Funding the Climate Denial Machine Crescendo to Climategate Cacophony Behind the 2006 Wegman Report and Two Decades of Climate Anti-Science - John R. Mashey
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