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The IPCC Fourth Assessment SPM

Filed under: — group @ 2 February 2007 - (Français) (Português) (Türkçe) (Español)

We’ve had a policy of (mostly) not commenting on the various drafts, misquotes and mistaken readings of the Fourth Assessment report (“AR4″ to those in the acronym loop) of the IPCC. Now that the summary for policy makers (or “SPM”) has actually been published though, we can discuss the substance of the report without having to worry that the details will change. This post will only be our first cut at talking about the whole report. We plan on going chapter by chapter, hopefully explaining the key issues and the remaining key uncertainties over the next few months. This report will be referenced repeatedly over the next few years, and so we can take the time to do a reasonable job explaining what’s in it and why.


First of all, given the science that has been done since the Third Assessment Report (“TAR”) of 2001 – much of which has been discussed here – no one should be surprised that AR4 comes to a stronger conclusion. In particular, the report concludes that human influences on climate are ‘very likely’ (> 90% chance) already detectable in observational record; increased from ‘likely’ (> 66% chance) in the TAR. Key results here include the simulations for the 20th Century by the latest state-of-the-art climate models which demonstrate that recent trends cannot be explained without including human-related increases in greenhouse gases, and consistent evidence for ocean heating, sea ice melting, glacier melting and ecosystem shifts. This makes the projections of larger continued changes ‘in the pipeline’ (particularly under “business as usual” scenarios) essentially indisputable.

Given all of the hoopla since the TAR, many of us were curious to see what the new report would have to say about paleoclimate reconstructions of the past 1000 years. Contrarians will no doubt be disappointed here. The conclusions have been significantly strengthened relative to what was in the TAR, something that of course should have been expected given the numerous additional studies that have since been done that all point in the same direction. The conclusion that large-scale recent warmth likely exceeds the range seen in past centuries has been extended from the past 1000 years in the TAR, to the past 1300 years in the current report, and the confidence in this conclusion has been upped from “likely” in the TAR to “very likely” in the current report for the past half millennium. This is just one of the many independent lines of evidence now pointing towards a clear anthropogenic influence on climate, but given all of the others, the paleoclimate reconstructions are now even less the central pillar of evidence for the human influence on climate than they have been incorrectly portrayed to be.

The uncertainties in the science mainly involve the precise nature of the changes to be expected, particularly with respect to sea level rise, El Niño changes and regional hydrological change – drought frequency and snow pack melt, mid-latitude storms, and of course, hurricanes. It can be fun parsing the discussions on these topics (and we expect there will be substantial press comment on them), but that shouldn’t distract from the main and far more solid conclusions above.

The process of finalising the SPM (which is well described here and here) is something that can seem a little odd. Government representatives from all participating nations take the draft summary (as written by the lead authors of the individual chapters) and discuss whether the text truly reflects the underlying science in the main report. The key here is to note that what the lead authors originally came up with is not necessarily the clearest or least ambiguous language, and so the governments (for whom the report is being written) are perfectly entitled to insist that the language be modified so that the conclusions are correctly understood by them and the scientists. It is also key to note that the scientists have to be happy that the final language that is agreed conforms with the underlying science in the technical chapters. The advantage of this process is that everyone involved is absolutely clear what is meant by each sentence. Recall after the National Academies report on surface temperature reconstructions there was much discussion about the definition of ‘plausible’. That kind of thing shouldn’t happen with AR4.

The SPM process also serves a very useful political purpose. Specifically, it allows the governments involved to feel as though they ‘own’ part of the report. This makes it very difficult to later turn around and dismiss it on the basis that it was all written by someone else. This gives the governments a vested interest in making this report as good as it can be (given the uncertainties). There are in fact plenty of safeguards (not least the scientists present) to ensure that the report is not slanted in any one preferred direction. However, the downside is that it can mistakenly appear as if the whole summary is simply up for negotiation. That would be a false conclusion – the negotiations, such as they are, are in fact heavily constrained by the underlying science.

Finally, a few people have asked why the SPM is being released now while the main report is not due to be published for a couple of months. There are a number of reasons – firstly, the Paris meeting has been such a public affair that holding back the SPM until the main report is ready is probably pointless. For the main report itself, it had not yet been proof-read, and there has not yet been enough time to include observational data up until the end of 2006. One final point is that improvements in the clarity of the language from the SPM should be propagated back to the individual chapters in order to remove any superficial ambiguity. The science content will not change.

Had it been up to us, we’d have tried to get everything together so that they could be released at the same time, but maybe that would have been impossible. We note that Arctic Climate Impact Assessment in 2004 also had a similar procedure – which lead to some confusion initially since statements in the summary were not referenced.

How good have previous IPCC reports been at projecting the future? Actually, over the last 16 years (since the first report in 1990), they’ve been remarkably good for CO2 changes, temperature changes but actually underpredicted sea level changes.

When it comes to specific discussions, the two that are going to be mostly in the news are the projections of sea level rise and hurricanes. These issues contain a number of “known unknowns” – things that we know we don’t know. For sea level rise the unknown is how large an effect dynamic shifts in the ice sheets will be. These dynamic changes have already been observed, but are outside the range of what the ice sheet models can deal with (see this previous discussion). That means that their contribution to sea level rise is rather uncertain, but with the uncertainty all on the side of making things worse (see this recent paper for an assessment (Rahmstorf , Science 2007)). The language in the SPM acknowledges that stating

“Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise. Understanding of these processes is limited and there is no consensus on their magnitude.”

Note that some media have been comparing apples with pears here: they claimed IPCC has reduced its upper sea level limit from 88 to 59 cm, but the former number from the TAR did include this ice dynamics uncertainty, while the latter from the AR4 does not, precisely because this issue is now considered more uncertain and possibly more serious than before.

On the hurricane/tropical strorm issue, the language is quite nuanced, as one might expect from a consensus document. The link between SST and tropical storm intensity is clearly acknowledged, but so is the gap between model projections and analyses of cyclone observations. “The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period.”

We will address some of these issues and how well we think they did in specific posts over the next few weeks. There’s a lot of stuff here, and even we need time to digest it!


364 Responses to “The IPCC Fourth Assessment SPM”

  1. 301
    David B. Benson says:

    Re #298 & #299: Jeremy Kenyon & SecularAnimist — As an amateur, I opine that the sea stand will rise about 15 meters. But I have no idea how long this will take. Nonetheless, long range planning suggests stringent controls on development at lower elevations.

    Regarding drought, Hadley Centre offered some predictions regarding various regions. I believe the report stated that indeed the American Midwest will become dryer. Also of concern is the monsoon in South Asia, falling too soon back into the ocean instead of on the land.

  2. 302

    [[Even more than that, for many people whose religious beliefs deny evolution, evolution is an extreme threat to their hopes of an afterlife. Thus evolution denies their hopes for immortality, and forces them to confront their own impermanence. ]]

    In what way does accepting evolution prevent belief in an afterlife? It seems like a non sequitur to me. All I can say is that I believe in both.

    [Response: This is actually the telling point. Refusal to accept scientific results (whether evolution or climate change) rests upon perceived connections to values that are much more intrinsic than science. The key to avoiding such a response is not to insist on the science, but address the perceptions. i.e. demonstrate that evolution doesn't have any implication for the after life (ask the Pope for instance), and that climate change doesn't mean that everyone has to go back to living in caves. - gavin]

  3. 303
    SecularAnimist says:

    Barton Paul Levenson: “In what way does accepting evolution prevent belief in an afterlife?”

    Wow, this is surely getting way off-topic not only for this thread but for this site — I know, I started it.

    What I had in mind was people who have specific beliefs about an afterlife for their “eternal soul” that are part of a religious belief system that also includes beliefs such as the Biblical creation story (the Earth is 6000 years old or whatever). To the extent that evolution challenges their beliefs about the origin of life and of human beings, it may challenge the entire structure of their religious belief system, and thus not only their sense of their place in the world as a “special creation” of God, but their specific beliefs about “eternal life” after death.

    Of course it is entirely possible to have naturalistic beliefs about some sort of continuation of what we think of as consciousness, or of elements of the human personality, beyond death; and this is a subject that is and ought to be within the bounds of scientific consideration and examination. The work of researchers such as Ian Stevenson into “cases of the reincarnation type” — i.e. young children who spontaneously talk about what they experience as “memories” of a “previous life”, which are found through investigation to correspond to the actual experiences of an actual deceased person that the child could not know about through conventional means — would be a good example of this.

  4. 304

    It was already pointed out in this thread but not continued that the raised CO2-level causes health problems. I just read a research report (in Finnish -sorry) showing that 800ppm is the threshold. When office rooms get over 800 ppm, people have quickly increasing number of symptoms and health problems. Today this is mainly problematic in cold climate as you have to insulate buildings well and through ventilation you loose energy. But quite soon it will be difficult to maintain indoor CO2-levels below 800ppm. My empty conference room downstairs has moderate ventilation running all the time and 500ppm according to my Vaisala CO2-sensor. When it is occupied with fifteen people and the ventilation is running on maximum, it is difficult to keep below 800ppm. How much more difficult this will become when we get to outdoor 600ppm. Will we all get a permanent headache even when outdoors if we reach 800ppm. How do we fare in 1250ppm as that also is inside the possible IPCC scenarios. Perhaps this is not climate science, but us futurists are generalists and this certainly is closer to the topic of this thread than religious wonderings why chimpanzees and bonobos are not part of the genus Homo as they should be if the naming rules of evolutionary science were obeyed even in the field of biology itself instead of religious dogma – or the afterlife that actually was discussed.

  5. 305
    Marguerite Rathbone says:

    Nowhere does Global Warming address if the frequency of Volcanic eruptions has decreased in the last 200 years. I do feel we must take care of our home (earth) but is the earth’s core heating up from other sources as well?

  6. 306
    Blair Dowden says:

    Re #304: Any information I could find on carbon dioxide health effect says they start at 1% (10,000 ppm). For example, this source states: “The Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) have set workplace safety standards of 5,000 ppm as an 8-hour time weighted average (TLV-TWA) exposure, and 30,000 ppm as the short term exposure level (STEL).”

    This is a long way from 800 ppm. Perhaps other pollutants are associated with high carbon dioxide levels in office buildings.

  7. 307
    Hank Roberts says:

    Yeah, they’d let you run a skip loader, but would they let you drive a car? run a corporation?

    Workplace safety rules aren’t meant to be levels not to exceed but okay to almost reach; they’re meant to warn of conditions where people are likely to be hurt.

    They’re not saying those levels define a level the workplace can all but attain regularly.

    And remember too, workplace exposure hour totals are reached around one workday, then interrupted by many more hours of non-workplace exposure.

    A lower residential exposure for more hours may be worse, answering that takes work — good work that’s statistics. Like understanding second hand smoke, eh?

    It’s interesting to me to look back a bit at the history of earlier products that had consequences the market didn’t foresee, wilfuly blind often enough. Lead in gas, lead pipe, lead in paint, mercury, vinyl carbonyl, chlorofluorocarbons, coal, formaldehyde, trans fats.

    I felt like I got an education and a half watching the public showboating around climate change, while being tempted ever cynically as to what seemed to be going on in politics with reasons never clear, or added at the last minute, before a bill was signed.

    I wonder if in retrospect the other big battles over materials in the marketplace in the past also show the fine hand of the professional opinion-maker. It’s certainly not novel now, but media spinning must have been a bit heavyhanded in the past, in retrospect, and might be interesting to dig into. Certainly tobacco’s been good at it for decades and still is.

  8. 308

    Re #304, thank you. The other pollutants can well explain the results of the study. The study mainly concentrated on the required ventilation level and they measured also levels of small particles etc. and found a good correlation with the level of CO2 of 800ppm but they did not measure CO2 levels independently or rule out the other pollutants as it was not their research aim. Sorry I was too hasty and made a wrong conclusion.

  9. 309
    Tavita says:

    The SPM says there is no significant anthropogenic warming at Antarctica. Yet it also says that “New data since the TAR now show that losses from the ice sheets of Greenland and Antarctica have very likely contibuted to sea level rise over 1993 to 2003.” Can someone at RC please explain why there is no significant warming in Antarctica and if this is true how the Antarcitic could have contributed to sea level rising?

  10. 310
    Blair Dowden says:

    Re #307: I was hoping for some facts, ie. what studies have actually been done on carbon dioxide exposure at low (by industrial standards) exposures. For example, what testing was done to set the OSHA 5,000 ppm standard? How valid is the Finnish study mentioned in #304? I am suspicious of single studies that come up with results greatly different from the scientific consensus.

    And by the way, there have been flawed studies exaggerating the effects of chemicals or second hand smoke, as well as bogus “science” trying to cover up the problem.

    Just give me the facts, preferably in peer reviewed papers.

  11. 311
    Hank Roberts says:

    Sure, Tavita. The ocean’s warmer. The ice around the edges, where the glaciers run down to the sea then push out from there to become floating sheets of ice, has melted from underneath and cracked (flexing as tides and waves move the floating part at the edge of the ‘grounded’ ice). During the warmest periods, meltwater on the top in the summer can run down through the cracks. Meanwhile, back at the middle of the continent, the two mile thick ice cap still is quite cold all the time, so snow continues to fall and accumulate there. So far, anyhow.

    There has been a whole lot of science done on these issues.
    http://scholar.google.com/scholar?q=antarctic+ice+sheet&hl=en&lr=&scoring=r&as_ylo=2002

    This reply from me, an amateur reader here like yourself. An expert will be along to correct and improve my answer soon, I trust. Look for responses from the people named in the sidebar under “Contributors” for real scientists’ answers here.

  12. 312
    tamino says:

    Re: #308

    Sorry I was too hasty and made a wrong conclusion.

    Risto, a willingness to admit a mistake, and a preference for the truth over being “right” all the time, are hallmarks of enlightenment. They’re also exceedingly rare, especially on the internet. You just moved up a dozen or so notches on my credibility scale.

  13. 313
    Hank Roberts says:

    >306
    see also: http://www.biomedcentral.com/content/backmatter/1476-069X-1-3-b1.pdf
    “ASHRAE standards allow for up to 700ppm CO2 above background in office buildings …”

    There are no standards for private residences I can find, but the ASHRAE level is far below the lowest one Pete found for industrial jobsites.

  14. 314

    [[Nowhere does Global Warming address if the frequency of Volcanic eruptions has decreased in the last 200 years. I do feel we must take care of our home (earth) but is the earth's core heating up from other sources as well? ]]

    I can’t see how it could. The radioactive elements in it have been decaying for 4+ billion years (which is one reason the interior of the Earth is as hot as it is); tidal friction from the Sun and Moon can’t really affect the heat of the interior on a large enough scale, and in any case, they’re not changing on a human time scale. I’m not saying you’re wrong, but as far as I can tell there’s no known mechanism to heat up the core any more than it already has been.

  15. 315
    Blair Dowden says:

    Re #313: Carbon dioxide is being used as a proxy for general air quality, because it is easy to measure. The ASHRAE Journal states: “The ASHRAE guideline value is based on the association of elevated carbon dioxide concentrations with unacceptable levels of body odor, and not on any health or comfort impacts of carbon dioxide itself.”

    The only valid way to study this question would be to add pure carbon dioxide into a variety of existing working environments and see at what threshold there are measurable effects. Of course, the participants must not know this is happening as that would bias the results. I don’t know if such studies have been done. There may be ethical questions about gassing people without their consent.

  16. 316
    Tavita says:

    Hank, thanks for answering my question concerning sea leve rise at Antarctica. I should have looked harder before bothering the thread. I ran across this link that answers the other part of my question concerning lack of warming at Antarctica.

    http://www.realclimate.org/index.php?p=18

  17. 317
    MrGreen says:

    From the WMO, Dec 11, 2006 – http://www.wmo.int/web/Press/PR_766_E.doc: “A consensus of 125 of the worldâ��s leading tropical cyclone researchers and forecasters says that no firm link can yet be drawn between human-induced climate change and variations in the intensity and frequency of tropical cyclones.”

    From the IPCC 4AR SPM, page 16 – http://www.ipcc.ch/SPM2feb07.pdf: “Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs. There is less confidence in projections of a global decrease in numbers of tropical cyclones. The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period. {9.5, 10.3, 3.8}”

    “After some prolonged deliberation, I have decided to withdraw from participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). I am withdrawing because I have come to view the part of the IPCC to which my expertise is relevant as having become politicized. In addition, when I have raised my concerns to the IPCC leadership, their response was simply to dismiss my concerns.” http://sciencepolicy.colorado.edu/prometheus/archives/science_policy_general/000318chris_landsea_leaves.html

    [no "yelling" please. Bold font should not be used in extended blocks. Next time post will be deleted]

  18. 318
    Hank Roberts says:

    >add pure carbon dioxide
    I dunno, did you read that PDF cite? They took two university buildings and ran their HVAC systems differently, so one accumulated higher CO2 levels, as you suggest. Agreed, they didn’t add pure CO2, but that never happens in real life either. It’s not clear from your quote whether people actually produce more body odor with enhanced CO2 or just smell each other because of poor ventilation. Point being if the background level doubles, ventilation isn’t going to take indoor environments below it, regardless.

    Don’t commercial greenhouses boost CO2? As I’m sure some university experiments have done. Again I don’t know if anyone actually adds the pure gas.

    What became of the Biosphere II record data, anyone have access to it? They filled the dome in a hurry at the end of the setup, and loaded it with pure topsoil instead of layering rock and mineral soil under a layer of thin topsoil, duff and leaf litter, which doomed their experiment before they even closed the seals — buried too deep, topsoil dies, it’s mostly living organisms after all. But it probably did produce a relatively pure boost in CO2 in that situation, and they didn’t have a big crowd of people in a small room as with the other studies.

  19. 319

    Re #310, #318

    I found other studies that also referreed to special circumstances in specific factories, submarines etc. The research I refer now was used to decide the allowed CO2 level, suggested was 5.000ppm. 8.000ppm has been shown to cause problems as a long time level and 5.000ppm in some animal tests. The topic has been under quime much study in Finland and my sources are in Finnish. But I quote the references of the last paper I checked. The health effects that correlated with the 800ppm must have been caused by other issues and CO2 was only a good proxy for the general office air quality. The study itself was of good quality by the state research centre and did not make the claim that I mistakenly did.

    Borum, VF, Schaefer, KE ja Hastings, BJ (1954): The Effecto of Exposure to Elevated Carbon Dioxide Tension over a Prolonged Period on Basal Physiological Functions and Cardiovascular Capacity, US Navy Med Res Lab Rept 241, 1-19.

    Ebersole, JH (1960): The New Dimensions of Submarine Medicine, N Engl J Med 262, 599-610.

    Echt, A, Burroughs, GE, Rubman, MH, ja muut (1998): Carbon Dioxide Exposures to Medical Personnel as a Result of Wearing Surgical Isolation Suits, Appl Occup Environ Hyg 13, 87-90.

    Edge, CA (1987): Indoor Air Quality Lessons from Submarine Environmental Systems, Proceedings of the ASHRAE Conference IAQ 87, May 18-20, Arlington, Va, 255-260.

    Gray, SP (1950): Pulmonary Ventilation and Its Physiologic Regulation, Chas. Thomas Pub., Springfield, IL.

    Gros, P, de Madre, J ja Dobel, M (1987): Fatal Accident in a Computer Science Centre: Prevention of Roisks Caused by Accidental Discharge of Gaseous Extinguishing Agents, Securite Med Travail 76, 40-42.

    Guillemin, MP ja Horisberger, B (1994): Fatal Intoxication due to an Unexpected Presence of Carbon Dioxide, Ann Occup Hyg 38, 951-957.

    James, JT ja Gardner, DE (1996): Exposure Limits for Airborne Contaminants in Spacecraft Atmospheres, Appl Occup Environ Hyg 11, 1424-1432.

    Louis, F, Guez, M, Le Bacle, C (1999): Intoxication par Inhalation de Dioxyde de Carbone, DMT- Documents Med Travail 79, 179-194.

    Messier, AA, Heyer, E, Braithwaite, WR, ja muut (1983): Undersea Med; viittaus MAK-Werte, Kohlendioxid, 4.7.1983.

    Nutall, JB (1958): Hazards of Carbon Dioxide, JAMA 168, 1962.

    OVA (1994): Hiilidioksidi. Onnettomuuden vaaraa aiheuttavat aineet. Turvallisuusohje, Chemas Oy, Helsinki, 8 s.

    Riley, RL, Bromberger-Barnea, B (1976): Monitoring Exposure of Brewery Workers to CO2: A Study of Cellar Workers and Controls, Arch Environ Health, 92.

    Schulte, JH (1964): Sealed Environments in Relation to Health and Disease, AMA Arch Environ Health 8, 438-451.

    Seter, AJ (1994): Allowable Exposure Limits for Carbon Dioxide during Extravehicular Activity, Govt Reports Announcements & Index (GRA&I), No. 1, 1994, 42 s.

    Zugibe, FT, Costello, JT, Breithaupt, MK, ja muut (1987): The Confined Space-Hypoxia Syndrome, J Forensic Sci 32, 554-560.

  20. 320
    Blair Dowden says:

    Re #319: Thank you, Risto. I think it is pretty clear that carbon dioxide has no direct health effect (on people, at least) until it reaches a few thousand parts per million. This should not be surprising, because complex life evolved under CO2 levels higher than 1000 ppm, and that has been the normal state except for a few ice age periods, such as now. So while there are many reasons it is not a good idea for the Earth’s atmosphere to reach 800 ppm, direct health effects of carbon dioxide is not one of them.

  21. 321
    Pat says:

    I haven’t yet had time to read all the comments, so please forgive me if this is already covered, but:

    Are there any maps (surface or other) on easily accessed sites showing not just (seasonal and annually averaged) projected temperature and precipitation, but pressure, winds and currents, humidity and cloud cover (of various types), etc. In particular with the cloud cover, this may make it easier to understand how cloud cover feedback would work and what the uncertainty in this feedback would mean – and what is the magnitude of that uncertainty anyway?

    One thing I would like to find is a quick (if that’s at all possible) summary of how the components of the climate-weather system might change – does the Hadley cell speed up, and how would that affect momentum transport? Would the Hadley cell expand (I’ve gotten the impression that’s a yes)? If greater energy release in tropical cyclones were not realized, would the heat instead be released in disorganized activity or be transported poleward into midlatitude weather? Would midlatitude storm systems move more slowly (longer rainy/cloudy periods with longer sunny/dry periods in between, perhaps) or have shorter or faster lifecycles? If the diurnal temperature range decreases, would that cause the mixed boundary layer – to the extent that it is convectively mixed as opposed to wind-mixed – not get as deep during the day but persist longer into the night (which would suggest to me, given same surface relative humidity, that daytime low-level cloud cover would be reduced where it is part of the boundary layer)? I’ve heard that the boundary layer might actually do the opposite – get deeper – which could then increase low level cloud cover, where it is near the threshold for doing so.

    It would be interesting to break it down – for example, with cloud feedback – frontal and extratropical cyclone clouds, mesoscale convective system clouds, tropical cyclone clouds, other deep cumulus clouds, low clouds over mid-high latitude oceans, low clouds over cold currents in subtropical oceans, etc…

    Is there a way to estimate minimum and maximum conceivable cloud feedbacks – ie if all the parameterizations go one way vs another?

  22. 322

    [[Are there any maps (surface or other) on easily accessed sites showing not just (seasonal and annually averaged) projected temperature and precipitation, but pressure, winds and currents, humidity and cloud cover (of various types), etc. In particular with the cloud cover, this may make it easier to understand how cloud cover feedback would work and what the uncertainty in this feedback would mean - and what is the magnitude of that uncertainty anyway?]]

    There’s a project called ISCCP (International Satellite Cloud Climatology Project) which is attempting to quantify and map cloud occurrence. You can find a lot about it on the web; here’s one link:

    http://isccp.giss.nasa.gov/

    That being said, at least some of what’s being published on the web in ISCCP’s name seems amateurish. For instance, I saw one page where the cloud fraction at each level was simply added to provide a figure for mean world cloud cover of 76.8%. The correct procedure is to assume random overlap (see, e.g., Kiehl and Trenberth 1997 — Bull. Amer. Meteor. Soc., 78, 197-208), and applying that to the data given comes up with 56%, which is much more in line with other published estimates.

    [Response: Actually it's a correct procedure, but it's a function of how ISCCP sees clouds - i.e. since the satellites look down they does not see clouds that are hidden from above. The ISCCP total is more like 63% though (maybe you were thinking of the HIRS analysis?). A bigger issue is whether ISCCP can detect the very thin cirrus clouds that are very optically thin (which is most of the uncertainty). - gavin]

  23. 323
    Mike says:

    The Telegraph are claiming “Cosmic rays blamed for global warming”. Do they have a point or is it their usual Monckton-type stuff?

    Keep up the good work

    Mike

    http://www.telegraph.co.uk/news/main.jhtml;jsessionid=LB0NKK1YNVN2LQFIQMFSFFWAVCBQ0IV0?xml=/news/2007/02/11/warm11.xml

  24. 324
    Lynn Vincentnathan says:

    RE the science v. religion thread (#300, 302), I think this is important for the topic of the IPCC report.

    First, as a professor who teaches on religion (& its differences from/similarities to other belief systems, such as common sense, magic, science), we need to clarify these differences/similarities. Religion is both a belief & value system; while science is only a belief system (with values kept at bay or shelved, if you will). In this regard, religious values, such as “thou shalt not kill” are pertinent and linked to the IPCC report, since it does imply that we are or will be killing people through the various effects of AGW; religions and humanistic value systems that hold this value would also need to include as killing, the farmers who commit suicide due to GW-enhanced severe drought conditions. We’re not talking about establishing guilt in a court of law, but in a court of morality.

    Religion deals with both the “seen & unseen” (the material/empircal world and the spiritual world); while science is limited to the material/empirical world (and that is one of its strengths). So anything science has to tell us must be taken seriously by religion, even if it goes against the earlier prescientific dictums in the holy books (in the past there was no separate field of science; there was only religion/science/philosophy/ethics/history as one endeavor). If the belief is that, say, God created the material/empirical world, and also made humans intelligent, then a religious person cannot deny anything science reveals, or they would be denoucing the Creator. Therefore truly religious people MUST accept the IPCC report (with all its caveats, of course), but the moral aspect of religion, requires religious persons to focus on the high end, and to the extent that they think the science might be wrong, then wrong in underestimating the problem. Also there is even a higher end danger, since religion also deals with the unseen, and that is the person’s soul could end up in a place even hotter than a globally warmed world, if they persist in failing to mitigate AGW (there is absolutely no way science can disprove a spiritual afterlife, since the spiritual realm is not in its purview, and is a matter of faith-belief, not empirical-science belief).

    Hence there is nothing in the IPCC to dissuade a religious person from accepting and responding positively to it; in fact such a person must accept it, if they really believe God created the world (which science has revealed was done through the awesome and intricate and astounding process of evolution & not with a presto-chango magic wand).

    However, alas, we are not only religous or cultural (belief/value) beings, but also psychological and social beings, so it is uncomfortable & inconvenient to accept one’s guilt in AGW, or that one might be more closely related to apes than one would like to be, the cockaroach too (though from a purely religious view, there is nothing ugly about being more closely related to any of God’s wonderful creation).

    Anyway, what Gavin pointed out (#302), about AGW being (falsely) linked to having to retreat to the cave, is pertenant here, and those who are not religious enough to trust in God’s providence, and thus may be stymied or angered with this fear, should be advised that it is a false fear & there is much evidence to the contrary, that reducing GHGs can make us better off economically, while increased GW will surely harm us economically.

    Would that America truly be a religious nation; then we would see ready acceptance of the IPCC report and enthusiatic and vigorous action to mitigate GW.

  25. 325

    Lynn, I think you’re taking a battering ram and rushing through an open door. I don’t think “religion” has had much influence on the AGW debate at all. It’s right-wing politics and big corporate money that are behind AGW denial, not “religion.”

  26. 326
    H. M. Ward says:

    Looking at this from the business layman’s (non-scientific) perspective. Why can’t science develop a process (similar to photosynthesis is my non-scientific guess) that extracts CO2 from the aptmosphere thus lowering the levels of CO2 causing greenhouse gas? We can desalinate water, convert oil to any number of products and reverse any number of other processes why not this one? Is it that complex, impossible?

    One other note part of the problem particularly in the US, IMHO, is the method and message that for the past two decades that has been utilized to warn about global warming. The message has been one of dire consequences in the year 2100 and sacrafices in emissions that need to happen now. Americans are so short sighted that all they see/hear are the sacrafices they will need to make now with no payback in their lifetime. Heck they can’t agree on how to fix social security and medicare which are going to be technically bankrupt in 30 years or so how do you expect them to care about the temperature in the year 2100 which is 93 years away?

  27. 327
    James says:

    Re #326: Such processes exist: the reasons they’re not likely to prove practical all come down to cost. It takes energy to extract CO2 from air, still more energy to store it as gas, while to convert it back to carbon takes more energy than you got by burning the fossil fuels to begin with.

    As for your second point, I still can’t manage to see where the sacrifices are going to come in. For instance, I’ve made a bunch of energy-saving improvements to my house, and as a result my power & heating bills are probably less than half what my neighbors pay. If that’s a sacrifce, I say lead me to more of them!

  28. 328
    Don Macdonald says:

    To change the subject a bit, I am a climate change policy advisor in one of the provinces in Canada and am having a lot of trouble explaining the IPCC projected temperature rise “best estimate” and “likley ranges” in terms that senior executives and elected Ministers can follow. I know that the best estimate and “likely range” are relative to a 1980-1999 baseline, but this doesn’t help much when explaining it to a lay person. Further, to the average person, a warming of a few degrees doesn’t sound bad – especially in Canada in February (currently -19C)! We were thinking of comparing these projected rises to the global average pre-industrial revolution temperature (around 13 C I think?) – would this be a fair comparision? Is this the right number? Does anyone have a more layman’s description, or story, of what these projected temperature rises could mean, even if it isn’t from IPCC approved text? I promise not to quote anyone!

    Thanks………..Don Mac

  29. 329
    David B. Benson says:

    Re #328: Don Macdonald — I encourage you to find the Hadley Centre report which describes projected changes on a regional basis. In general terms, the changes will be not good to bad for farmers and foresters. Look at what a few warm winters have done to the forests of eastern British Columbia.

    Locally, the expectation is for wetter winters and longer, dryer summers. The agricultural scientists are already working on new cultivars for the projected conditions in this region. I suspect the Canadian prairie provinces will respond similarly.

    Stressing the biological changes should find receptive ears. We all have to eat…

  30. 330
    mark s says:

    Hi there,

    I’ve just been reading New Scientist (Feb 10), and it makes reference to the suggestion of some scientists, that the greenland ice sheet will physically collapse long before it melts!

    I’ve had a poke about and found some interesting stuff, like that Greenland is probly three islands, with 2 horizontal ‘superfjords’ in it! Also, because of the thickness of the ice sheet, most of greenland is well below sea level (up to 500m alledgedly), which reminds me of Pat Neuman’s questions, about isostatic rebound.

    Anyone got any idea what the ‘superfjords’, and the land level means, for the physical collapse, which would come long before melting?

    Does anyone have any more on this? because I havent read this suggestion before… Maybe the KGB have been meddlin :-)

    By the way, i thought the scientists were ultra-conservative on AR4, i would have liked to see them hockey-stick there neck out a bit more, really!

    I’m not really very nationalistic, but who thought it was a good idea to hand the leadership on AR4 to the NOAA. Is there something i should know about the Met Office (who led on the first 3 reports)? subliminal leftist messages in our UK weather forcasts? We should be told. :-)

    Never mind though, folks, its only the planet we are gamblin with. ha ha(not!).

    I’m off to go an listen carefully, to a weather forecast!

    regards

  31. 331
    Ella says:

    Just adding to the concern of Global Warming,I may only be 11 years old but I know alot about the enviroment and whats happening to it,I also have an extreme love and passion for wildlife,but enough about me, another reason Global Warming might be happening could be the exause from our cars and trucks ( trucks in perticular).

    Ever drive down the the street and see this monster truck then look up and see this little pipe at the top bellow out black smoke,and see the smoke just disappear?

    Have you ever wondered where that black smock goes,(well I dont have the exact answer), but it goes into the enviroment, I know that much.And at that perticular moment, I get real fired up about how were going to kill our selves by eather drowning our selves or just having so much natural disasters that we ripe the Earth apart.I mean it’s rediculose how much black,discusting smoke goes into the air every day,(again, I dont have the exact answer, but I know it’s alot)

    All we need to do( and I really mean “need”)is to eliminate all those big,bulky discusting trucks and that alone will make a huge difference, and to have a bonus, people could actully start using those battery opperated cars, I mean there cute! And you’ll save loads of money on gas.

    This will help animals in the arctic like polar bears, pengiuns, and seals have a better life and us too!

    love Ella

  32. 332
    Brian Bahnisch says:

    Re #273, I’ve printed out the two versions of the SPM and compared them. As far as I can see, no text has been left out in the more recent 18 page document compared with the earlier 21 page version (still available at the BBC site.) The main differences are as follows.

    The figures and tables have been incorporated into the text, and the SRES box moved to the end.

    The margins are narrower, hence more type on the page.

    The footnotes are in larger typeface.

    Some bits have been cleaned up, eg Figure SPM-5 and the error identified earlier.

    There still seems to be a problem at the top of page 3. The increase of carbon dioxide emissions between the 1990s and 2000-2005 is given, but when it comes to land-use only the 1990s is identified. So the more recent value and the comparison are lost.

    By the way it is small comfort to know that our persistent droughts in Australia are only more likely than not linked to human contribution.

  33. 333
    Hans Erren says:

    re 331
    Ella the black smoke is soot, not CO2, and there are good filters that can take that out. Some scientists think it’s the soot that causes the glaciers to vanish.

  34. 334
    tamino says:

    Re: #331

    Ella, to understand the workings of something as complex as global climate takes a lot of knowledge; this can be learned in school. To put that knowledge to good use takes the will to do so; this can’t be learned. But it seems to me that you’ve got it already.

    I apologize for all the hardship my generation is dumping on your generation; you deserve better. Many of us are trying to make a difference, so you’ll have a better world to grow up in. If you learn about earth and the environment, and hold on to your will to do something about it, you can make a much bigger difference. Keep hope alive. Good luck.

  35. 335
    John L. McCormick says:

    RE # 331

    Ella, it is good to see another young person drop in on RealClimate.

    While much of what is said on these pages might be a tad above your learning curve, I urge you to begin reading and asking your parents, teachers and librarians for answers and book titles.

    There is so much to learn about our home -planet- and it is truly a fascinating and complex system of ocean, air, ice,land and vegetation interacting and making life possible for 6.5 billion of us and the countless hundreds of billions of critters large and small.

    Global warming is the consequence of what our and past generations have caused and it will take the caring and wisdom of many future generations to protect our planet.

    Please start today to educate yourself about the basics of the changing global atmosphere and how it is interacting with the entire planet. You will find a fascinating and rewarding life of science ahead. I promise you.

  36. 336
    H. M. Ward says:

    James,

    the sacrifices are people will not be able to drive their big SUV’s live in their big McMansions etc. [edit] Furthermore industry will be required to cap their emissions, that involves additional costs which then requires that shareholders sacrifice profits. Most shareholders of corporations are large institutions (mutual/hedge funds) that are rated/graded/paid on performance. If the current return on shares is diminished by additional costs related to reducing emissions that will not have any benefit for 100yrs guess what the shareholders are going to think of these new costs.

    As for the processes involved couldn’t we use Hydrogen Fuel cells to eliminate the CO2 from the atmosphere? I have to believe the technology is there or available that will make this a viable process and then separating the C and the O into their separate parts and storing the C somewhere. I readily admit I am no scientist and there are far smarter people right on this site that could probably develop this process. Bottomline if this issue is setting us up for such dire consequences in the future why isn’t someone working on something like a process like this instead of just consistently bombarding us with “the sky is falling, the sky is falling” reports and instead focus on finding a solution that is something other than “you need to stop doing what you are doing”. Yes conservation is part of the solution but it can’t be the only solution yet it appears to this lay person the only one scientists are offering.

    One other point that I take personal issue with is the whole idea/link that I read so often in the media claiming that Global Warming is coming from humans “polluting” the air. Last time I checked CO2 is the most abundant green house gas that is causing global warming (please correct me if I’m wrong) and the last time I checked CO2 is not a pollutant unless of course you consider everytime a living thing exhales polluting the air.

  37. 337
    Lynn Vincentnathan says:

    #333, Hans brings up an important point. Our actions that produce GHGs, such as driving gas-guzzlers, also cause many other harms. We really do need a holistic picture of all this. Global warming in conjunction with all the concomitant environmental harms from our wasteful & thoughtless actions will be much much worse than global warming alone. It’s probably even a multiplier effect of harm, rather than an additive effect.

    So it extremely behooves us to reduce our GHGs, & along with that the same corrective measures will also reduce our other harms.

    By using a low-flow showerhead, you not only reduce the energy to pump & heat the water (and the GHGs and other pollutants & harms involved in mining, shipping, and burning those fossil fuels), but you also save water & slow the quick retreat of our water tables. Future generations will also need water, especially on those hot globally warmed days that are already in the pipeline. And we reduced our shower consumption by 1/2 (we actually tested it with a bucket and a timer) without feeling any difference from the wasteful showerhead. And finally we figure the savings in water bills and water-heating costs at about $100 a year, or $2,000 over the 20 year lifetime of that $6 showerhead (with off/on soap-up switch). And reducing shower time by 30 seconds or a minute saves even more!

    So, Ella (#331) & all who have eyes to read, there is something you can do (if your house doesn’t already have them)–install low-flow showerhead–and get your friends to do so. That would be a great start & the money you save can be used for compact fluorescent bulbs and other measures. Then all the savings from all those measure, plow it into something like the extra cost for wind-power (we have to pay about $5 to $10 more each month for 100% wind power from GreenMountain).

    Some say reducing GHGs is too expensive, but if they can only raise that initial $6 (which I remember B.E.C. (before environemtnal correctness) as being very hard to raise, but where there’s a will, there’s a way), the rest is easy.

  38. 338
    mark s says:

    Re #331

    I can’t help but admire (and be inspired by), that post. Thanks Ella.

  39. 339
    Ian Perrin says:

    Professor Timothy Ball says “The other thing that you are seeing going on is that they have switched from talking about global warming to talking about climate change. The reason for that is since 1998 the global temperature has gone down — only marginally, but it has gone down. In the meantime, of course, CO2 has increased in the atmosphere and human production has increased. So you’ve got what Huxley called the great bane of science — “a lovely hypothesis destroyed by an ugly fact.” So by switching to climate change, it allows them to point at any weather event — whether it’s warming, cooling, hotter, dryer, wetter, windier, whatever — and say it is due to humans. Of course, it’s absolutely rubbish.”

    Does he have a factual basis for this global cooling? If so, can you tell me where to find it?

    [Response: No. To find out what's going on (and it's still globally warming) look directly at the temperature records (e.g. GISTEMP) - there are ups and downs because of the 'weather' noise, but there is a sustained and obvious long term trend. And it's the trend that we are talking about -not the wiggles. -gavin]

  40. 340
    Priya says:

    I really dont know much about these climate changes & Global warming, but i do hav lots of doubts regarding these. Will global warming lead to extreme hot of cold places & extreme cold of hot places? Some of the Scientists say that the symptoms of global warming has already started & the climate is going unpredictable & they hav no idea about what will be the real cause behind this…
    Moreover there has been many Natural Disasters in several places that has never experienced before in these many years. Does these Natural Disasters hav anything to do with the Magnetic Field Changes of the Earth…? i mean i’ve read somewhere that the magnetic field is changing from the direction of North to South to the direction of south to north which has been discovered through the study of Rocks found on the Ocean floor & measurements of the magnetic field polarity in ancient volcanic lava flows. And this seems to be a routine with a time gap of some thousand years. Will this be one of the reasons for Earth Changes?
    Will you please tell me the right answers to my doubts & questions? And above all can u tell me whats going on around here?

  41. 341

    Priya — don’t fear “Earth Changes” too much. Natural disasters occur at about the same rate they always did, with the exception of storms becoming more powerful due to global warming. The Earth’s magnetic field really doesn’t have much influence on the climate. It’s an extremely weak field, for one thing — about 0.5 Tesla, as I remember. Cosmic rays do get through the atmosphere better when the magnetic field is low, and there’s some thought that that might affect cloud formation, but no clear evidence as of yet.

    The Earth will survive global warming and magnetic field reversals; it has in the past. Global warming will hurt mankind economically for a while, but civilization will still survive.

  42. 342

    I have mostly managed to disprove “confusnic” claims against AR4, presented in a local Finnish blog run by the largest newspaper. I have hoped professionals would enter the discussion to help but the Finnish professionals mainly enter the discussion only through traditional media. I have found good answers here to many questions and have learned quite much while searching and reading through the older threads also. But now I have a question that I cannot answer even though I know that the burden of proof should fall onto the other side. I am not even sure that I understand the question as I have difficulty to understand where the excess energy goes.

    Does Lindzen claim that according to the calculated effects of the greenhouse gases the earth should be 75C but as it is only 15C, the dynamic effects of the earth somehow loose the excess. And thus if the direct effect of CO2 is from 0.5C to max 1.2C this should also be reduced by the same multiplier and the real effect is 0.1C to 0.3C.

    I have answered as I believe myself that the climate models are themselves theories of the major effects and the causal effects that they include and if they fit to the measudred data and known physical laws, then the burden of proof is elsewhere. However I would appreciate some more advanced student to teach me or point me to a source where I can study this so that I could answer the question better.

    [Response: Sorry, I have no clue as to the source of the claim that the planet should be 75deg C without greenhouse gases. The standard calculation for a planet with the same albedo but no atmosphere gives -18 deg C. The climate sensitivity is around 3 deg C for a doubling of CO2 (see our older posts for why). -gavin]

  43. 343
    Steve Latham says:

    Re 339,
    How long has the IPCC been called that? Was it called IPGW prior to 1998? No, this is just Tim Ball (someone with little credibility) diminishing his credibility further. Being Canadian, desmogblog.com has some good stuff on him including the impending failure of a lawsuit in which he tries to clear his good, er, tries to get legal backing for his overstatements regarding his credentials.

  44. 344

    Gavin, I am familiar with the climate sensitivity, but the rumor level claim put to Lindzens mouth did not refer to the planet without greenhouse gases but actually claimed that the calculated temperature of earth _with_ the greenhouse gases (I guess starting from the base level you refer and adding the calculated effects of all the greenhouse gases) should be +75 deg C, and as it in practice is less, then there “must be” dynamic effects that get rid of heat and so the calculated direct effect without multipliers “must also be” reduced by the same proportion – (I guess by multipliers what was meant was that increasing CO2 increases temperature and that increases humidity and that again increases temperature and this is how you get the 3 deg C). I am sorry this is murky as I am only guessing what the person intends to claim and he only refers to Lindzen but does not give me any reference to peer review -level papers. Basic intent of the person was to deny the practical effect of CO2 or minimize it down to 0.1 to 0.3 deg C. I understand that the models give 3 deg C and they fit with data but I still have difficulty disproving the claim in any intelligent way as he has read many of the denial papers and very often refers to Lindzens models.

    I do really appreciate your patience with us laypeople. We do learn (slowly and some parts).

    [Response: Thanks for the clarification, however, I'm still none the wiser. There is no calculation I am aware of that indicates that temperatures should be as high as 75 deg C - unless you can get a reference, you are fully entitled to ask your correspondent to 'put up or shut up'. With respect to climate sensitivity, this does NOT come from the models - it comes from the observations (as outlined in the post I linked). That the models give roughly the same thing is a validation of the models, not a proof. -gavin]

  45. 345

    Thank you Gavin. I did browse the posts you pointed to me, I do appreciate that there is a huge amount of measurement behind the current climate sensitivity and I did learn that the instead of multiplier I should have used feedback. English is my second language and climatology perhaps the tenth. I did find one older paper by Lindzen which I read without any possibility to fully understand it, but it did resemble the claim that my correspondet gave me. Page 351 he talks about 350K without convection Рunder the topic climate dynamics referring to M̦ller&Manabe 1961. (annual Reviews in Fluid Mech. 1994. 26 353-78)
    http://www.atmos.washington.edu/~jcasola/pcc587/refs/lindzen94.pdf
    My correspondent did acknowledge my claim that Nasa has tested and disproved Lindzens claims with measurements but claimed that Lindzen has since then explained what went wrong. These explanations have not I assume been published in scientific journals. I already told him that it is up to him to prove that IPCC is wrong and not me as a layperson to disprove things that he cannot show support for other than with causal claims. I guess I will stick with that. And it may well be that Lindzens theories are too tough for a layperson to disprove with any causal logic anyway and I guess prediction and consequent measurements are always the final proof anyway to the scientists. Not the rhetoric. But sadly rhethoric does work with opinion building amongst the laypeople. My current rhetoric in this case is that Lindzen is the only scientist making this claim and all the others believe that he is wrong and have evidence for it that we as laypersons are unable to read or understand properly without excessive studying and not always even then can people give up the dead ends as I would believe Lindzens case seems to show.

  46. 346
    chen says:

    I estimate that the result of AR4 that the temperature of the earth will rise to 300C.

  47. 347
    Pat says:

    Re 322: Thanks

    Re 345: Yes, that seems familiar – the argument being that without convection, radiative equilibrium produces a much higher lapse rate (rate of temperature decrease with height) in the troposphere – this part is true. The ability of warm air to rise/ cool air to sink sets a maximum allowable lapse rate in the atmosphere, the dry adiabatic lapse rate. Moist convection tends to reduce the lapse rate even further.

    It is silly to argue that this implies the warming should be reduced from a change in CO2 relative to that given by the IPCC, because even a simple 1-dimensional (ie a single column of atmosphere representative of a global average) model will take into account convection. (Of course, uncertainties in changes in convection will lead to uncertainties in feedback, but in principle it is accounted for)

  48. 348

    [[[Response: Sorry, I have no clue as to the source of the claim that the planet should be 75deg C without greenhouse gases. The standard calculation for a planet with the same albedo but no atmosphere gives -18 deg C. The climate sensitivity is around 3 deg C for a doubling of CO2 (see our older posts for why). -gavin]]]

    I think he meant 0.75 C, which is what Lindzen did try to identify as the climate sensitivity in one of his papers — can’t find the cite offhand, but I remember the paper. It was ripped to shreds by several papers written in response shortly thereafter.

  49. 349

    #347 Thanks Pat, I guess this was what I was searching for, but clearly I need to learn to formulate my questions better. I will try to find a source to explain the structure of the models that I could use as a source to show that convection has already been included (I have basic modelling experience on some other scientific fields but naturally that does not help much with climate models). The thread where I have been arguing against the denialists with two other amateurs is maintained by the largest and most influential Finnish newspaper and is probably read by some of the reporters and editors. Over 300 posts now and mostly I think I have coped well with the help of IPCC AR4 and this site and the links I have found here but this was too tough to solve in a short time.

    Generally the discussion in Finland is going towards consensus of the threat. Opinions differ what actions should be taken and a new atomic power plant is on the agenda for many. Acceptance levels of the general population to regulative measures on cars and other issues are high enough to allow the politicians to make desicions but some industries are still very hesitant claiming that we need to get China committed and we need to take care of our competitiveness. Jorma Ollila, who is chairman of both Nokia and Shell, gave a very committed interview on the necessity that there has to be political action now and even if China would not immediately follow. Jorma Ollilas appearance before AR4 changed the atmosphere of the Finnish discussion as much as the IPCC report or maybe more as he has been very prominent in Finland being the man who was CEO of Nokia during the phenomenal rise of Nokia. Prominent industry leaders have quite an impact if they dare make their personal opinion clear.

    And Gavin, thanks – validate, not prove. This is not mathematics. Sloppy of me.

  50. 350
    Priya says:

    Hello Barton,
    Thank u very much for your kind response. But i just want to tell u that i’m not afraid of all these earth changes. i was just eager to know what’s going on… Moreover, my main hobby is collecting information about earth, beyond space, the unexplained phenomenon, black holes, Bermuda Triangle, underworld civilizations & several other spots that has wierd science & mysteries behind it. I hav been doing this for about 5yrs(since i was 14), but i have’nt got any clear evidences. I know i’m too small to learn about all these things. But i’m very much intrested in this. I admired to become a researcher or a scientist to learn about all these in detailed, but due to certain circumstances, i could’nt do so. Besides i always had a thought that several research centers & scientists hav found something about the wierd things happening around the world or is about to happen. But they kept it secret for some reason. Is it true…?. But my mum told, that sometimes certain unacceptable things cannot be revealed to the world, as people always need proof to prove it and there will be a lot of Oppositions. So better hide for good. I hope she’s right as these things really don’t hav any proofs isn’t it…?
    Well, likewise i had lots of questions in my mind, but i did’nt hav a chance to get it cleared as i could’t find a relevent person. U are the first one to give a good response to me. Thank u once again…


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