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Comments 121551 to 121600:

  1. The human fingerprint in global warming
    Tarcísio #48 I am no expert, but the temperature of the CO2 at the moment of its release does not seem relevant to the carbon cycle. The molecules will be mixed up and at the same temp as the surrounding atmosphere within a few minutes.
  2. Martin Hedberg at 08:25 AM on 30 March 2010
    The human fingerprint in global warming
    @50 GFW. Forgive my English, I am a Swede. I think I didn't express myself clear enough (#49). As the partial pressure of CO2 in the air has increased, so has the diffusion from air to ocean and biosphere. When our emission were smaller, some years ago, so was the partial pressure of CO2 in the atmosphere and hence the diffusion. (However the picture also includes sea-surface temperature, phytoplankton and more). It does not contradict what you call my prediction (However I would rather call it a thought experiment than a prediction). The carbon cycle is defined as flows of carbon, measured in mass (typically Giga tons). As we started to emit carbon, the carbon cycle changed. Not only the reservoars changed, but also the flows. Question: How could there be some law of nature that 50% of our emissions were to be removed from the atmosphere by oceans and biosphere? Put another way: If we doubled our emissions tomorrow, why would the oceans and biosphere increase there removal with the same increment? I still conclude that humanity has managed to keep the emission (by coincidence) about twice as large as the the net extra amount of CO2 being removed by ocean and biosphere. Thus the (about) 50% is not a constant. It can change, either if we change our emissions or if one or more parts of the carbon cycle changes. /Martin
  3. The human fingerprint in global warming
    JohnD, regarding historical cloud data the same folks who recovered beautiful pictures of the Moon from ancient Lunar Orbiter tapes are now doing a repeat performance w/old Nimbus weather satellite data stretching all the way back to the 1960's. They've already turned out some lovely product, some sample shots available here via NSIDC.
  4. The human fingerprint in global warming
    @35 Stuart. Thanks! per meg relative to original is likely the correct interpretation. I made two errors that canceled to about a factor of two. @49 Martin. I don't think you're right about that. I believe the short term ocean sink is closer to a simple diffusion equilibrium between the atmosphere and the upper (well mixed layer) of the ocean. That would explain why it's been a roughly constant fraction (even when human emissions were half what they are now, contradicting one of your predictions). Then the remaining fraction has to remain in the air until slower processes remove it (organic "rain" to the bottom of the ocean, geologic burial, etc.) @42 Chris. What I just said to @49 Martin may be a useful way to think about it, but it's a considerable simplification. The IPCC AR4 says
    About 50% of a CO2 increase will be removed from the atmosphere within 30 years, and a further 30% will be removed within a few centuries. The remaining 20% may stay in the atmosphere for many thousands of years.
    which is a more nuanced statement based on a more complete understanding.
  5. Martin Hedberg at 05:31 AM on 30 March 2010
    The human fingerprint in global warming
    To Chris G #42. I may not be an answer to your question, but worth mentioning: It is no law that it should be about half of our emissions, its more of a coincidence that we have increased the emission to be about twice the amount being absorbed by oceans and biomass. If we reduced our emissions by 50% tomorrow, about the same amount would be absorbed and hence the amount of CO2 in the atmosphere would stay the same. If we doubled our emissions tomorrow, only 25% would be absorbed. Natures capacity to absorb our emissions should rather be measured in tons (mass) than in percentage. Preindustrial carbon-cycle was smaller than the carbon-cycle is today. The absorption in water and biomass has increased as our emission has increased. /Martin
  6. Was there a Medieval Warm Period?
    I´d like to know more about data infilling in this kind of reconstruction. Mann´s paper (at least this one) does not say much about it. Can someone give me some research tip?
  7. Tarcisio José D at 05:14 AM on 30 March 2010
    The human fingerprint in global warming
    I question the assertion that the relationship c13/c12 may indicate that the increase of CO2 in atmosphere is the result of burning fossil energy. As the CO2 from the combustion, it is logical that he, for his temperature, to go position in the upper layers of the atmosphere. The absorption of CO2 by oceans and plants tend to dominate the CO2 released by decomposition of organic matter (CO2 cold).
  8. The human fingerprint in global warming
    johnd, it's not the (known) effect that matters but its claimed global trend which should drive the frequency.
  9. The human fingerprint in global warming
    Riccardo at 07:46 AM on 29 March, 2010, as far as I know there is no data regarding cloud cover, and certainly no historical data which is most unfortunate. The relationship of cloud cover and hotter days and warmer nights is as well understood as is the relationship of standing in the rain without an umbrella and getting wet, but whether or not anyone has been able to measure the effects of either and translate that into some objective measurement does not alter the reality of either.
  10. The human fingerprint in global warming
    Stuart @35, go to the link I posted @ comment 4. I think you'll find that per meg means change relative to Nitrogen. Ah, now I realize that my link doesn't work (why?), so here I'm going to risk raising our host's ire by posting a url: http://scrippso2.ucsd.edu/how-does-one-relate-ppm-and-meg-units%3F Here is the url I tried to link previously: http://geoweb.princeton.edu/people/bender/lab/research_o2n2.html Sorry John. So, if 4.8 per meg oxygen = 1 ppm, and eyeballing indicates about -200 per meg oxygen (so 42 ppm) and about +25 ppm CO2, it looks like oxygen has dropped quite a bit more than CO2 has increased. As others have indicated, though, we know quite a bit of CO2 has gone into the ocean and soils. If 50% of CO2 or less remains in the atmosphere, then we would expect a decline of at least 50 ppm oxygen. However, because of ocean warming, oxygen is being released to the atmosphere, and therefore we see a decline of only 42 ppm. I hope that's correct.
  11. The human fingerprint in global warming
    Thanks Tom, my take-away point from the links is mainly that the sinks that absorb CO2 quickly, in aggregate, also tend to release it quickly, and that the sinks which result in a long period of sequestration are also slower acting on the absorption side. That's pretty much where I was going, but the links helped me get there. Now I'm thinking about ocean cycles and speculating that there may well be 'echos' of CO2 content in the atmosphere as water that went to depth during a period of high atmospheric CO2 content resurfaces. I wonder what that would look like on a graph.
  12. The human fingerprint in global warming
    Chris G, there are multiple sinks and sources of CO2, and they operate on different time scales. Click on the links and look at the pages I point to in my comment on another thread. I'm not sure those will answer your question, but if not, say so.
  13. The human fingerprint in global warming
    I'm having trouble reconciling a couple of things and I'm hoping someone here can help me with it. The fraction of CO2 that humans emit annually that also stays in the atmosphere is around 40-50%. (Some studies indicate a possible change in the fraction, and some do not, but that is not the point I'm having trouble with.) The CO2 that we put in the atmosphere takes hundreds of years to be absorbed by natural processes. So, my problem is that, if around half of human emissions is absorbed quickly, and that has been the case for most of the time that we've been adding to the CO2 content significantly; why does it take so long to absorb the rest? Is it the case that surface layers on land and sea quickly reach an equilibrium with the atmosphere, but that turning over the land takes, umm, a very long time, and turning over the ocean layers takes hundreds of years?
  14. Does record snowfall disprove global warming?
    Thanks for the response, I went and checked the link to Roy Spencer's blog, I am glad for your ability to put forward the layman's description :). A bunch of questions arise on his content to gain more understanding, but unfortunately not enough time to go and understand this in detail, like most things. Thanks, keep up the good work.
  15. Arkadiusz Semczyszak at 23:08 PM on 29 March 2010
    The human fingerprint in global warming
    P.S. Thank you John for the Polish version ...
    Response: Don't thank me, thank Irek Zawadzki who did the translation :-)
  16. Arkadiusz Semczyszak at 23:07 PM on 29 March 2010
    The human fingerprint in global warming
    This evidence (John C.) is very logical and precise. But not quite. Skeptics still have a lot of work yet. Two examples: ice cores and temperature of the lower stratosphere. 1st Data from ice cores. - even if we reject all 19 charges Jaworowski (http://www.someareboojums.org/blog/?p=7) it will last us - being for decades - "diffusion in firn" - smoothing results from ice cores. - results from the ice core (to 1958) do not have any data to confirm the land. Only data from the cores from the seabed (foraminiferal, Spongia - low resolution in time and are often subjected to high pressure - the slow dissolution of carbonate), confirm the data from the cores. - Data on the land of ancient CO2 concentrations in the atmosphere: delta 13C, ratio of C3/C4 plants, stomata index - they are fundamentally different from data from ice cores. Yes, we can say that these proxies affect temperature, humidity, precipitation. However, - these vectors function; for example, the stomatal index - in a different direction than for the C3/C4 and delta 13C. However, if we compare Graph: "Speleothem evidence for changes in Indian summer monsoon precipitation over the last 2300 years" on those page: http://people.ku.edu/~lgonzlez/ (Kansas University); whit this graph: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC129389/figure/f2/, we see the same pattern of all 3 proxy changes over time. [...] E.g. this paper: "Climate and CO2 modulate the C3-C4 balance and _13C signal in simulated vegetation" Flores et al. 2009, Clim. Past Discuss., 5, 1187–1213; proves that the role of humidity is negligible here, as well as (probably) the temperature. The delta 13C, C3/C4 (density of stomata?) determines only the concentration of CO2. 2nd After each eruption "into the stratosphere," the lower stratospheric temperature increases (http://omsriram.com/GlobalWarming_files/Global19.jpg.). Despite an increase in CO2 concentrations in the atmosphere. Since the explosion of Mount Pinatubo, over 15 years throughout the stratosphere the temperature continues to rise (http://www.acd.ucar.edu/Research/Highlight/strat-cooling.jpg) ...
  17. What CO2 level would cause the Greenland ice sheet to collapse?
    gallopingcamel writes: You say that NOAA is not throwing away station data. There is a simple way to test this statement. I have emailed the Canada Weather Office to ask them what station data they are currently providing to NOAA, NASA and UEA/CRU. Just out of curiosity, would you mind posting the text of the email you sent? I'm curious about how you worded it. You should be aware that there are actually around 100 stations in Canada north of lat. 60 that have contributed data to GHCN in the past. The problem is that only four of those have been updated with new data since 2008.
  18. A peer-reviewed response to McLean's El Nino paper
    jonicol, here's a quote from the abstract of McLean et al. 2009: The results showed that SOI accounted for 81% of the variance in tropospheric temperature anomalies in the tropics. Now, is it your understanding from that sentence that McLean et al. showed: (a) SOI explains 81% of the variance in tropospheric temperature anomalies in the tropics full stop, or (b) SOI explains 81% of the residual variance in tropospheric temperature anomalies in the tropics after removing the long-term trend, or (c) something else? It seems to me that McLean have been rather coy about this. It also seems to me that (b) is the correct answer. There is only a single reference to "81%" in the McLean et al. manuscript, in paragraph 19: [19] Using the same technique of derivatives with data exclusions for periods of volcanic activity the line of best fit is dLTT(trop) = -0.0311*dSOI + 0.0252, [Equation 3] where R2 = 0.81. Note that that regression model is based on the derivative data, not the raw data. Given this, what do you think about the following remarks from the Conclusion of McLean et al. 2009? We have shown that the Southern Oscillation is a dominant and consistent influence on mean global temperature. [...] [This] study has shown that natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature There are two obvious problems here. First, as you yourself emphasized, McLean et al. did not analyze global temperature data, despite the repeated reference to "global" in their conclusions. Second, as shown in Paragraph 19, their calculations were done on a transformed version of the temperature data from which the long-term trend had been removed. Thus, it is not possible to draw any conclusions from their work about whether SOI is a "dominant" influence or whether it is a contributor to "trends in global temperature." A paper demonstrating that SOI has an effect on short-term interannual climate variability would not be very interesting, as everyone already knows that. A paper demonstrating that SOI has an effect on long-term trends in climate would be very interesting, but McLean et al. didn't do that. Finally, jonicol writes: Why do all these criticisms come from un named authors - are people ashamed to show their real name because they have no confidence in what they are saying. The authors of Foster et al. 2010 are all listed at the top of the paper, along with their institutional affiliations.
  19. How we know global warming is happening, Part 2
    Okay, here are the trends 1979-present for all the data sets: UAH: +0.132 HADCRUT: +0.156 RSS +0.156 NCDC: +0.162 GISS: +0.163 Amusingly, if you round them to two places, all except UAH are 0.16. In any case, there's not exactly a huge gap here.
  20. A peer-reviewed response to McLean's El Nino paper
    Albatross You seem unable to understand that the key graph in McLean et al. is Figure 7. This is a plot of the raw data (NOT differentiated data as claimed by Foster et al.) relating SOI, as defined in the paper, against the TROPICAL lower troposphere temperature (LTT)measured from the microwave emissions in the lower troposphere MSU in the band 20 degress North to20 degrees south - not the whole globe. However, since the sun is ocverheasd in the tropics, most of the energy causing higher temperatures on earth are exprienced in the tropics. The point made in McLean's paper is correct and is being totally, perhaps deliberately or if not ignorantly, misinterpreted. The AGU/JGR has broken a long tradition of the right of reply to any criticism of a published topic. This is no surprise in fact since McLean'spaper and the blocking of a reply to any critique by manipulating the editors and reviewers in JGR is openly discussed in the CRU emails recently released. John Nicol. P.S. Why do all these criticisms come from un named authors - are people ashamed to show their real name because they have no confidence in what they are saying. JN
    Response: I've reproduced the Mclean Figure 7 graph here:

     

    If you look carefully, you'll find that the top box uses RATPAC weather balloon data while the bottom box uses satellite MSU data. Eg - it's not one continuous datasets but two data sets spliced together. Most importantly, the mean values of RATPAC-A and UAH TLT data during their period of overlap differ by nearly 0.2 K. Splicing them together introduces an artificial 0.2-degree temperature drop at the boundary between the two.

    The most curious feature of this graph is that the graph is split into different panels precisely at the splicing boundary. This obscures the difference between the weather balloon dataset and the satellite dataset. It's a misleading way to display a graph and yet is obviously effective in persuading people into thinking that the long term trend in ENSO correlates closely with the long term warming trend.

    For the record, I don't hide my name nor does Stephen Lewandowsky. However, the people who really matter are the authors of Foster et al 2010 who are all named.
  21. The human fingerprint in global warming
    Bob Close writes: Where is the verified experimental or actual measurements to support this strange assumption, or its corollary that ongoing atmospheric increases in CO2 above 400-500ppm will automatically create a tip over effect into runaway spiraling catastrophic warming? "runaway spiraling catastrophic warming" seems a bit over the top, don't you think? Nobody is suggesting "runaway" warming a la Venus. Doubling CO2 will probably lead to around 3C of warming on average. The actual impacts of this will be negative enough, particularly due to amplification of the hydrologic cycle.
  22. A peer-reviewed response to McLean's El Nino paper
    John Cook, Stephan Lewandowsky (ABC, Drum Monday, 29 March,2010), Foster et al. and others seem to be unable to read. The findings reported in McLean et al refer to the TROPICAL values of the MSU data, NOT to GLOBAL temperatures. By the Way, John is a very skilled computer scientist who has been working on climate science matters for about four years, in which time he has had the support of internationally renowned climate scientists such as Bill Kinninmonth, one time head of our own, Australia's BOM. John is enrolled as a PhD student and has started out well. It is a measure of the validity of his claims that so many interested persons have sprung out of the woodwork to criticise him and his work, which challenges the “consensus” without ONE single word of science to back up their arguments. Once upon a time, any one worth his scientific salt relished a controversy and welcomed criticism of his/her more than praise, because it made you think! Not any more it seems. Any challenge is seen as a threat to the comfort of conformal thinking – actually conformal unthinking! I have not yet looked up Cook's or Lewandowsky’s crededentials but have glanced through their articles in which they have both demonstrated their obvious inability to refute John McLean's arguments. The paper by Foster et al., which I have studied very closely, does nothing but present a mixture of first/second university theory of the Fourier Transform, including what they thought was a clever simulation – a few random numbers, a linear trend – looks impressive and oh so clever, but all quite well known and absolutely of no consequence here. McLean et al.'s taking of the first derivative ONLY to determine very nicely the seven month time lag shown in Fig 3 is perfectly legitimate and confirms other rougher and less accurate work as is appropriate in a paper of this nature and of this quality. The key graph, is their Figure 7, which Foster et al. have quite mistakenly claimed was detrended. No such thing. It is a plot of ENSO or SOI against the TROPICAL MSU data without any differentials being taken. As tudent in about grade 9 could see that from the caption! It just goes to show that many people who claim to be "scientists" are not only incapable of understanding science but also incapable of reading. As Dean of Science at an Australian University years ago, I used to be particularly interested in students ability in English, as it is a good measure of how well they will perform in science, even the hard sciences such as my own Optical gas spectroscopy and atomic physics and mathematics, geology and chemistry. A careful comparison of the plots in McLean's Figure 7 with other graphs in the paper shows immediately that the FORMER are differentials of the data time series shown in 7. John Nicol PhD (Physics)
  23. The human fingerprint in global warming
    Oh, yes... I forgot about the role of burning hydrogen in my quick calculation. For long carbon chains, you get more oxygen going into carbon dioxide than water, so my calculations are in the ball park, but I'd be interested in seeing a slightly more detailed sum.
  24. The human fingerprint in global warming
    John (or somebody),can you explain a bit more about the units in figure 3, and can we draw any conclusions from the implied stoichiometry ? If I postulate that a lot of carbon has come from methane (oil/gas field "flaring" or release from biogenic stores such as deep-sea clathrates or arctic perma-frost regions), rather than coal, then would or should (or might?) this show up in both ? By which I mean specifically: a) the carbon isotope ratio, and b) the amount of oxygen consumed: that is one atom of carbon will consume one molecule of O2, but one molecule of methane will consume twice as much O2. Does methane in deep-sea clathrates or "permafrost peats" show the same isotope distribution as "fossil-fuels" ? Also, when I look at figure 4, the stand-out effect is the large change in the methane absorption-band. For me, this is consistent with either release from "recent" biogenic stores (permafrost, peat etc) or possibly flaring-off from oil drilling. OK, I don't access to the numbers, but I presume that this issue has been addressed? Figure 1. The up-tick in atmospheric CO2 levels appears to predate the up-tick in CO2 levels attributed to humanity. Why so? I'm intrigued by the addition of data about cement manufacture, something I hadn't thought much about before. I would love to see the estimated numbers on that.
  25. The human fingerprint in global warming
    On the other hand, I don't see the need to refer to the oxygen concentration at all. We know how much fossil fuel we're burning, we know how much oxygen it takes to burn it. Is the argument that the oxygen is not being replenished by photosynthesis? I guess I have heard some skeptics make that argument.
  26. The human fingerprint in global warming
    GFW (and others who may have a more concrete answer): I'm guessing the value on the right is the fall in O2 concentration relative to the O2 concentration, rather than relative to the full atmosphere. Just eyeballing it, O2 falls by about 200 "per meg" and CO2 rises by about 20 ppm in the same period. Oxygen is about 20% of the atmosphere, so if my interpretation is correct, that's a fall of 40 ppm of the oxygen concentration for a rise of 20 ppm CO2. One oxygen molecule becomes one CO2 molecule during combustion and about half the CO2 ends up in the ocean, not the atmosphere... so the figures are looking remarkably consistent at this point. To anyone familiar with the numbers or papers, is this looking correct? I'm at a loss to explain how people still don't accept that about a third (and rising) of the CO2 in the atmosphere is there because of humans.
  27. The human fingerprint in global warming
    Interestingly enough Richard Alley by his own admission is not a climatologist but rather an Earth Scientist/Geologist like Bob
  28. The human fingerprint in global warming
    Bob Close, you asked how CO2 can be the main driver of global warming, when its direct effect is smaller than the effect of water vapor. Here is the thread where that is explained: Water vapor is the most powerful greenhouse gas. CO2 is the driver of other mechanisms that also increase temperature. Water vapor increase is one of those. Those same positive feedbacks would be driven by an increase in the Sun's radiance, if that were happening now. (But it's not; if anything, radiance has been decreasing since at least the 1970s and maybe as far back as the 1950s.) See climatologist Richard Alley's talk at the 2009 American Geophysical Union conference, "The Biggest Control Knob: Carbon Dioxide in Earth's Climate History."
  29. The human fingerprint in global warming
    Bob Close wrote "However, this does not explain multi-decadal warming and cooling cycles evident in the historical data that appear on lack of other convincing evidence to be solar related." So what, Bob? Obviously a cross-decadal upward trend in CO2 or anything else cannot explain variations counter to that trend. Who is claiming it should? (Certainly not Trenberth!) CO2 would have to explain (track/predict/correlate with) all variations in temperature only if CO2 were the only cause of temperature. But a fundamental basis of climatology is that CO2 is not the only driver of climate. Therefore the correlation between CO2 and temperature will not (cannot, must not) be anywhere close to perfect unless the time span is long enough for other forcing and feedbacks both positive and negative to wash each other out. Even then, the correlation with CO2 will be much less than perfect, because other, non-washed-out forcings and feedbacks will interfere. But those effects can be subtracted from the correlation, leaving us with a much closer to pure correlation with CO2--which is much greater than zero. For example, the effects of the Sun's 11-year up and down cycles can be removed most simply by plotting the 11-year running average of temperature. More sophisticated analyses yield estimates of the proportion of temperature increase that is explained by (correlated with, predicted/postdicted by) various aspects of the Sun's activity. For example, solar radiance accounts for a substantial portion of warming for the first half of the 20th century, but not since then (see It’s the sun). A purer measure of the CO2 correlation also can be gotten by looking at total energy rather than only at air temperature, as Glenn Tamblyn explained well. Finally, as chris explained, the causal attribution of CO2 to temperature most certainly is not based only on correlation! The theory was started in the early 1800s and continued to be developed based on formal experiments on fundamental physics, for many decades before measures of the Earth's temperature were sufficient to even begin to look for observational correlations as empirical support for the theory's predictions. I suggest you get an overview by reading the free online book The Global Warming Debate.
  30. The human fingerprint in global warming
    John, I took a whack at explaining stratospheric cooling and I have to say it is difficult to get a handle on and to explain. The link below is my effort: Stratospheric Cooling The key points I took from this: 1) Ozone loss has contirubuted to about 50% of the cooling, CO2 the other 50%. 2) Ozone has begun to increase since 1993 which will offset some of the GHG-caused cooling, especially in the lower stratosphere. 3) The greatest cooling appears in the upper stratosphere near 40–50 km. Ozone concentration above 35 km is minimal so ozone depletion is much less a factor at these levels than cooling due to CO2.
    Response: "I took a whack at explaining stratospheric cooling and I have to say it is difficult to get a handle on and to explain."

    Why do you think I spent one sentence on it then hurried on?

    That's a great resource you've got there on stratospheric cooling. I've added a new Further Reading section to the "It's Not Us" page linking to your resource. I've also added it as a resource in the Global Warming Links page on "It's Not Us". Thanks for the link!
  31. The human fingerprint in global warming
    Chris, whole heartedly agree. And it would be interesting to see VS continue on and start inputting all of the factors you state. There has already been corraboration from the likes of Tamino, Bart, Eduardo, etc. Not that they have sat around with a few beers and politely discussed it, there has been some hammering, but all have looked at the issue through the others eyes. What I find interesting about the VS thing, is that there is finally a dialogue happening. Over 700 posts, which 6 months ago, would more then likely have been shut down quite quickly. On Lucia's blog, Zeke, Carrott Eater, Nick Stokes not only post their views and results, but again, a dialogue. Here at John's, since I've been visiting, there has always been this courteous back and forth between disparate views. I just sense that there has been a "step change" in relationships between the pro and cons. Of course, like everything in this world, there will be a lag, before it manifests at the very top! Call me an optimist. It really does bother me to see all of the intelligence wasted by tribalism. I guess you could say that I am finding myself firmly planted in Judith Currie's camp. As Picard would say, "Engage!"
  32. The human fingerprint in global warming
    OK, as an Earth scientist and skeptic with no climate science background but an understanding of long term natural changes to the planet and solar system, you have established to my satisfaction that there is CO2 related AGW. However, this does not explain multi-decadal warming and cooling cycles evident in the historical data that appear on lack of other convincing evidence to be solar related. Also on the basis of (Evans 2006) GHG data percentages, water vapour is having a 25x proportionally massive effect compared to CO2 which is directly contributing less than 5% of the total effect. How then is CO2 the main driver of GW? Various authors have argued that the dominant WV effect is a direct result of the expanded evaporation cycle of warmer seawater caused by the CO2 effect, therefore CO2 is the main driver! Where is the verified experimental or actual measurements to support this strange assumption, or its corollary that ongoing atmospheric increases in CO2 above 400-500ppm will automatically create a tip over effect into runaway spiraling catastrophic warming? This critical data is now urgently required because without it one can only conclude that it is wishful thinking or worse to blame fossil fuel generated CO2 for most of the current global warming and its supposed undesirable effects. Lets get the science more exact and in perspective. Until we can clearly see that current climate changes are way outside the normal range over the last millennia, we should only conclude that mankind has (should)or can have a marginal effect on global climate. A possible exception being if we have a massive nuclear exchange creating a radioactive dust blanket thus cooling the planet for a while. This does not mean we should be complacent about the matter and not try to ameliorate our polluting way and thus protect the planet, as we clearly are massively affecting our environment by our burgeoning population increase and industrialization driven by our depleting fossil fuel resources.
  33. The human fingerprint in global warming
    Tom Dayton writes: It is merely a story on the San FranciscoExaminer.com blog by writer Tom Fuller, about scientist Bart Verheggen's suggestions about the statistics. Just to clarify -- As far as I can tell, there's no actual connection between the San Francisco Examiner newspaper and the "Examiner" web portal. Tom Fuller just seems to be a random individual who provides commentary at the latter site. He doesn't seem to be connected with the newspaper, though lots of web postings seem to identify him as "a columnist for the San Francisco Examiner".
  34. The human fingerprint in global warming
    nerndt, the effects of cosmic rays on cloud cover are discussed in It’s cosmic rays. Be sure to also click on the links in the "Related Links" box at the bottom of that post. Those other threads are the appropriate places if you want to continue discussing that topic. It is off-topic for this thread we are on now. By the way, you can easily find the appropriate threads by using the Search field at the top left of every Skeptical Science page. For example, you can search for "cosmic rays" or "clouds."
  35. The human fingerprint in global warming
    Leo, I second Chris's reply.
  36. The human fingerprint in global warming
    re: Leo G at 09:03 AM on 29 March, 2010 Leo, statistical analyses are meaningless outside of the context of the physics of the system of interest. One can set up false premises, and come up with any conclusions from a bit of statistical numerology. Your example is a case in point: the temperature rise to 1936 certainly wasn't natural (false premise). Atmospheric CO2 levels rose from 286 ppm to 308 ppm in the period from the mid-19th century up to 1936 (high resolution [CO2] record), and inspection of the long term CO2 record, together with understanding of human greenhouse gas emissions, indicates that this rise was not natural. That change in [CO2] should give a global surface temperature rise of ~0.3 oC at equilibrium under the mid range of Earth climate sensitivity to enhanced greenhouse forcing (3 oC rise per doubling of [CO2]). The global surface temperature rise in the period from the mid 19th century to 1936 was around 0.3 oC (e.g. Hadcrut reconstruction ). So it’s very likely that a substantial amount of the warming to 1936 was due to very large anthropogenic enhancement of greenhouse gas concentrations that had accrued already through the first third of the 20th century. Of course if you really want to understand the temperature evolution (over the last 150-ish years say), one needs also to factor in the rest of the known physics – i.e. the known aerosol emissions and their forcings; the known volcanic emissions, and the amplitudes of their negative forcings (these account for the suppressed late 19th-early 20th century temperatures); the solar contributions; the contributions from black carbon and from land use changes etc.; the response times of various elements of the climate system etc. etc…..i.e. the sort of attribution studies done here and here . To throw away all knowledge of the physics of a system, and then attempt to draw conclusions from a statistical analysis of a single parameter is hopeless for scientific understanding. Statistics is an adjunct to physical/empirical analysis. It has no meaning in isolation.
  37. What CO2 level would cause the Greenland ice sheet to collapse?
    gallopingcamel, the FACE experiment's topic of CO2 being sequestered by CO2-enhanced growth of trees is off-topic for this thread, so I've replied over on the thread CO2 Is Not A Pollutant.
  38. CO2 is not a pollutant
    This comment is my response to a question by gallopingcamel on another thread. This topic is off-topic for that thread, so I'm responding in this thread. The Duke FACE experiment (Free-Air CO2 Enrichment) of artificially fertilizing trees with CO2 is an important one. Its results are consistent with other experiments on other plants: Plants' growth is limited by whichever nutrient or other condition is in shortest supply or detrimentally high supply, or by inherent physiological limits. A plant whose growth is limited by water supply isn't going to grow more if you give it more CO2, or more sunlight, or more soil nutrients. If initially the CO2 supply is the limiting factor, then giving the plant CO2 will let it grow faster only until some other factor that was sufficient for the previous growth rate becomes the bottleneck for the higher growth rate. Farmers and gardeners know this, which is why they don't waste money by giving plants too much of any one thing. Even greenhouses whose air is spiked with CO2 don't have 100% CO2 atmospheres. "Detrimental conditions" include temperatures that are too high. Even if a plant has sufficient other nutrients and conditions to allow it to take advantage of extra CO2 to grow more, if that CO2 is accompanied by higher temperature, the temperature can slow growth. The net growth then will depend on the balance of the enhancement from CO2 and the detriment from temperature. But even if you keep all the nutrients and conditions in synch, there are inherent physiologic limits to growth rate. All plants in the world today have evolved for, or been bred for, approximately the current CO2 levels. There was no survival advantage of being able to use more CO2 than was available. Not all plants respond the same to increased CO2 levels. For example, the Aspen FACE experiment (different from the Duke pine tree FACE experiment) found that "aspen grow much faster in response to elevated carbon dioxide, [but] similar effects have not been observed in other trees species, notably oak and pine." And aspen in moist soil take advantage of additional CO2 by growing faster, but aspen in dry soil do not. In contrast, loblolly pines react oppositely: They grow more with extra CO2 only during dry years, not during normal or wet years. The bottom line is that
    "Forests will continue to be important to soak up anthropogenic carbon dioxide," says [the aspen FACE experiment's] Waller. "But we can't conclude that aspen forests are going to soak up excess carbon dioxide. This is going to plateau." "Aspens are already doing their best to mitigate our inputs," agrees Cole. "The existing trees are going to max out in a couple of decades."
    The Duke pine FACE experiment's Schlesinger said:
    Based on available evidence from the Duke experiment, “I’d be surprised if the forests of the world will take up more than one-third of the carbon dioxide from fossil fuel emissions in the year 2050, which is what our experiment simulates,” he predicted.
    More information on biologic carbon sequestration, with a number of links to even more info, can be found on an EPA page. Wikipedia has a broader page.
  39. The human fingerprint in global warming
    Excellent Post, very well written. Perhaps your best one yet. I have some questions that I will post later, but I wanted to first give you kudos.
  40. The human fingerprint in global warming
    Glen @ 22. VS has just done an analyses of temp rise, comparing up to 1936 (supposedly natarul) to 1936 to 2008 (supposedly more AGW). His result just simply states that the recent temp rise does not fall out of the boundaries of natural causes. He clearly states that this in no way disparages the CO2 hypothesis. He has not looked into that aspect yet. Who knows if he will. Tom - VS has not been debunked by Tamino. Tamino helped to show VS that temp is not a random walk, which he has admitted. What I see coming out of this post @ Bart's, is like here and @ Lucia's, we are starting to see more and more the possibility of "both sides" (Gawd how I hate that term!) starting to work together, putting strengths together to really nail this issue down. Eduardo has said that he would welcome working with a statistician of high calibre. Could the halls of hell be freezing over? Do you think that one day we may see a paper by M & M - Mann and McIntyre??? :)
  41. Glenn Tamblyn at 08:36 AM on 29 March 2010
    The human fingerprint in global warming
    manacker Your observation reflects a common fallacy in how people are looking at Climate Change. We live on the surface of the Earth and to us 'climate' is effectively air temperature. All the different climate models are making predictions about future air temperatures (among other factors) so we are interested in whether they are correct. However, the air isn't the climate. It is one part of it, albeit the part we are interested in. The climate is actually the air, oceans, land surface, ice and some would argue, the biosphere. And the key thing we need to be looking at if we are seeking confirmation of AGW is energy not temperature. Ultimately the theory is that multiple different factors - GH gases, H2O feedback, Aerosols, Clouds, Albedo change, Solar output variations an then the complex interactions of all these in the 3 Dimensional real world will lead to an energy imbalance for the planet - Energy Out being less than Energy In or the so called Radiative ImBalance. So there is a net accumulation of heat within the environment. So the key correlation is between Radiative Balance and Total Heat Content for the planet. And as John has shown well here, this connection is very clear cut. The ext important correlation is Radiative Balance vs the various factors causing it. Again John has higlighted these well here. The largest area of uncertainty is Aerosol/Cloud effects. Next is the break up of where the heat is accumulating. 90% or more is in the oceans with the atmosphere making up around 3%. The atmosphere is small in enegy terms compared to the oceans and various heat transfer mechanisms that operate between air and oceans mean that air temps can be volatile. Small, percentage wise, changes in the oceans can flow through to much larger changes in the air. Also, this combination of a large, slowly accumulating, heat reservoir and a smaller, volatile one also means that there can be significant time lags between an initial heat injection and the consequent temperature change in the air. So attempting to do a statistical correlation of one forcing factor vs one small, time lag dependent and volatile consequence is a rather meaningless exercise. I haven't read the article although I have heard of others like this done by econmists. Either they don't understand enough of the physics to know which correlations to look for, in which case their mistakes are honest ones. Alternatively the act of focusing on a narrow aspect of the science so it can be attacked is a classic strawman argument and a common technique of AGW denialists, in which case my view of them is less charitable. Look at the range of views put forward by denialists. How many of them are loudly trumpeting how radiative balance and Total Heat Content are the smoking gun that AGW is all a fraud. Rather cherry pick and keep the focus on small details. You can always pick the strawman when the real, live, 3 dimensional real man enters the room. Thats why the denialists don't touch this question.
  42. The human fingerprint in global warming
    I found a link to effects on solar bursts to cloud cover Precipitation, cloud cover and Forbush decreases in galactic cosmic rays References and further reading may be available for this article. To view references and further reading you must purchase this article. D. R. Kniveton School of Chemistry, Physics and Environmental Science, University of Sussex, Falmer, Brighton, BN1 9QJ, UK Available online 6 August 2004. Abstract The results of a study to explore variations in cloud cover, over regions that are minimally affected by rainfall and heavy rainfall, and that are coincident with variations in the galactic cosmic ray flux, are presented. Using an extensive record of global satellite derived cloud and rainfall products from the International Satellite Cloud Climatology Project D1 data series and Xie and Arkin (J. Climate 9 (1996) 840), epoch superposition analysis of a sample of events of short term decreases in the galactic cosmic ray flux, is conducted. Analysis of data that is largely free from the influence of rainfall and heavy rainfall, averaged over 10-degree geomagnetic latitude () bands reveals that cloud cover is reduced at high latitudes, and at middle and lower (including equatorial) latitudes over regions of relatively higher cloud cover, over both land and ocean surfaces, while increasing over ocean surfaces at middle and lower latitudes in regions of thinner cloud. Author Keywords: Cosmic rays; Clouds; Precipitation; Climate; ISCCP; Forbush decrease; Solar variability Article Outline 1. Introduction 2. Method 3. Results 4. Discussion and conclusion Acknowledgements References
  43. The human fingerprint in global warming
    Tom - thanks for your previous response to my question. Another question relavant to this debate: Does cloud cover change from daytime to nighttime? If so, by what amount? If for example cloud cover decreases 10% (SWAG - truly random numbers to give an example) when the sun hits the earth and increases 10% (SWAG 2) on the shaded side of the earth, wouldn't troposphere and stratosphere readings vary heavily based on cloud conditions? Clouds form the largest thermal blanket of the troposhere, followed by water moisture and then other gases. On a separate issue, I once heard (I'm afraid it was a while ago and I do not remember the source or time period for the events) that large solar wind bursts can send up to 10% of earth's cloud cover out into space. This could cause quick fluctuations in earth's temperature swings that would take years to recover. I once thought if we drastically expanded the Ozone hole we could quickly cool down the earth. Is this so? It would not be safe, allowing dangerous rays to hit the earth where the hole was made, but sure could cool things down quickly.
  44. michael sweet at 07:51 AM on 29 March 2010
    The human fingerprint in global warming
    Max, As others have mentioned there are other forcings besides CO2. Aersol forcings can account for much of the departure from CO2 increasing. John has another thread that discusses this. Where do you get your data for your claim of golbal cooling? What time period do you claim for this cooling? GISS shows continued increase, as does the NCDC data. Michael Sweet
  45. The human fingerprint in global warming
    johnd, do you have any reference to data showing a trend in cloud cover coherent with your claim? Or you are just throwing a hypothesis?
  46. gallopingcamel at 07:41 AM on 29 March 2010
    What CO2 level would cause the Greenland ice sheet to collapse?
    Ned (#64) and JMurphy (#65), You say that NOAA is not throwing away station data. There is a simple way to test this statement. I have emailed the Canada Weather Office to ask them what station data they are currently providing to NOAA, NASA and UEA/CRU. If it turns out that they are sending data on more than one station (Eureka) above 65N and three stations between 60N and 65N (WITHEHORSE, DAWSON and CORAL HARBOUR) I hope you guys will be gracious enough to apologise.
  47. The human fingerprint in global warming
    Well, Fuller article is just another example of people jumping to (wrong) conclusions after reading something the do not understand. We're getting used to this. The statistical debate is interesting and worth reading but it's a highly specialized field and not so easy to fully understand. In the meanwhile, better stick to good old (and rock solid) physics that tells us that surface temperature cannot be a random walk.
  48. The human fingerprint in global warming
    shargash said "isn't the greater warming at the poles than the equator also a fingerprint of the greenhouse effect?" Polar amplification can result from any positive forcing, although there is less known about past Arctic Oscillation. See Moritz, R.E., C.M. Bitz, and E.J. Steig, 2002: "Paleo-data show that Arctic SAT in the 20th century was exceptionally high compared with the previous 300 years and that this was likely caused by GHG forcing, although there is no consensus on the cause of the Arctic cooling during 1940 – 60. In the past 30 years, the AO has played a key role in Arctic climate change. It is not clear whether the AO has been as important before this period or how it will contribute to the future. Most GCMs underestimate the magnitude of the trend in the AO when forced with 20th-century radiative forcing and continue to simulate weak trends under future forcing scenarios. In addition, these models tend to produce a tremendous spread in their predicted future warming in the Arctic. Clearly, the spread in warming cannot be attributed to their simulation of the AO. It is more likely that the disagreement stems from the parameterizations of surface albedo, cloud processes, and other feedback mechanisms in the high latitudes."
  49. gallopingcamel at 07:33 AM on 29 March 2010
    What CO2 level would cause the Greenland ice sheet to collapse?
    Tom (#75), I was hoping for a comment on the FACE experiment or even on the idea that mankind has the power to defer the next Ice Age. My take on the latter point is that it can't be that easy. Imagine driving around in your SUV or Gulfstream IV (if you are Al Gore) because it is your duty to save the planet from the big freeze?
  50. The human fingerprint in global warming
    The frequency of cold and warm days and nights will be a function of cloud cover as much as anything, especially cold or warm nights.

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