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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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How the IPCC is more likely to underestimate the climate response

What the science says...

Select a level... Basic Intermediate

Numerous papers have documented how IPCC predictions are more likely to underestimate the climate response.

Climate Myth...

IPCC is alarmist

"Unquestionably, the U.N. Intergovernmental Panel on Climate Change (IPCC) was formed to build the scientific case for humanity being the primary cause of global warming. Such a goal is fundamentally unscientific, as it is hostile to alternative hypotheses for the causes of climate change." (Roy Spencer)

"Unquestionably, the U.N. Intergovernmental Panel on Climate Change (IPCC) was formed to build the scientific case for humanity being the primary cause of global warming. Such a goal is fundamentally unscientific, as it is hostile to alternative hypotheses for the causes of climate change."

Climate scientist Roy Spencer made this statement. He starts by suggesting something highly questionable isn’t open to being questioned. What he seeks to do is suggest, by inference, that the IPCC has an agenda, and this distorts the reports they produce. In other words, Spencer (and others) suggest that the IPCC exaggerates what the science says in favour of anthropogenic global warming. It is perfectly legitimate to question this assertion, since Spencer and others offer no evidence to support it.

Some critics go further, suggesting that the IPCC actively suppresses science that doesn’t support the theory that climate change is being caused by human activities. It is notable this ‘other science’ is rarely produced to support the accusation.

Does the IPCC accurately report the findings of science?

The IPCC was formed to report on a broad range of scientific enquiries into the climate, and our effects on it, and to summarise the science for laypeople. The science they summarise is published so it is simple to compare the primary science with the IPCC reports, and compare both to what actually took place.

There are numerous instances where the IPCC reports, which are summaries of published climate change science, have understated the case - hardly suggesting exaggeration in pursuit of an agenda. Here are some examples:

  • CO2 output from fossil fuels: observed emissions are close to the worst-case projections made by the IPCC, despite them offering a range of potential emission scenarios. (In fact, atmospheric CO2 is increasing ten times faster than any rate detected in ice core data over the last 22,000 years).
     
  • Sea-level rise is accelerating faster than the IPCC predicted. Actual sea-level rise is 80% higher than the median IPCC projection. By 2100 sea-level rise was predicted by the IPCC to be in the range of 18-59 cm. It is now believed that figure may be far too low, because estimates of contributions from Greenland and Antarctic ice-caps were excluded from AR4 because the data was not considered reliable. (This omission hardly supports the notion that the IPCC seeks to exaggerate global warming trends).
     
  • Each Arctic summer, sea-ice is melting faster than average predictions in the last IPCC report. The Arctic is experiencing a long-term loss of multi-year ice which is also accelerating.
     
  • The body of scientific literature has consistently shown that human greenhouse gas emissions are responsible for more global surface warming than has been observed over the past half century, whereas the IPCC only says that greenhouse gases are responsible for "most" observed warming over this timeframe.

In many similar cases, the evidence suggests that changes in climate are occurring faster, and with more intensity, than the IPCC have predicted. It is not credible to suggest the reports were biased in favour of the theory of anthropogenic global warming when the evidence demonstrates the IPCC were, in fact, so cautious.

In fact, there is evidence however to suggest that the exact opposite is actually the case, both in terms of the scientific evidence itself (see below) and the way the work of the IPCC is reported. A recent study (Freudenburg 2010) investigated what it calls 'the Asymmetry of Scientific Challenge', the phenomenon in which reports on science fail to evaluate all outcomes, favoring certain probabilities while ignoring others. They found that "...new scientific findings were more than twenty times as likely to support the ASC perspective [that disruption through AGW may be far worse than the IPCC has suggested] than the usual framing of the issue in the U.S. mass media".

Claims that the IPCC is alarmist are not supported by evidence, and there are clear indications that the opposite may be the case.

Basic rebuttal written by GPWayne


Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 5 July 2015 by skeptickev. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Comments

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Comments 101 to 136 out of 136:

  1. krisbaum @ 95... Upon a quick read of the paper you cited I can't find any reference even to the atmospheric lifetime or spacial distribution of black carbon. I don't think you've read the paper.
  2. krisbaum... I believe if you're talking carbon monoxide aerosols that would be generally accepted as anthropogenic, pretty much without saying. Unless you can think of other large sources of carbon monoxide.
  3. To clarify, as can be seen in this image of various emissions with short dwell times in the atmosphere, they have, as Krisbaum puts it "a very heterogeneous spatial distribution": However, just because concentrations are strongest near there source, and fall of rapidly with distance does not mean emissions do not result in significant concentrations hundreds of miles away, or that relatively remote locations will not have sufficient concentration to track changes in emissions. Indeed, if you look at the record for aerosol emissions (center top), you will see that individual cities are not clearly delineated by the concentrations, as would be the case if their typical transit distance was limited to 10 kilometers. In that way, aerosols are different from NO2 (left top), where individual industrial centers are easily delineated. What is more, significant concentrations of aerosols are still found a couple of hundred miles of the coast, again showing the absurdity of the 10 km claim made by Krisbaum. So, once again, while Krisbaum purports to have a problem with the IPCC citing Popper's "The Logic of Scientific Discovery" on falsification, and Kuhn's "The Structure of Scientific Revolutions" on paradigm shifts (just two of the very dubious claims of inadequate literature from Krisbaum's favourite source), he has no problem with citing non-academic websites and simply making "facts" up in support of his argument. Why then do we continue to tolerate his sloganeering? His own words have thoroughly discredited him; as has his refusal to look at the particular use made of particular citations for which he condemns the IPCC.
  4. Rob @101 - page 3 of the report Rob @102 - Bushfires for example generate huge amounts of carbon monoxide.
    Response: [DB] You have yet to fulfill the challenges you have assigned yourself in comments 81 and 94 earlier in this thread. You will be held accountable to fulfill those commitments.
  5. krisbaum @ 104... Ummm... No. Just read page three and there is nothing there that talks about the atmospheric lifetime or spacial distribution of black carbon. They discuss accumulation over time. There is certainly nothing there to support your 10 km statement.
  6. Tom@103 I was talking bout anthropogenic aerosols not emissions. Why post a diagram of CO, CH4 etc when they are NOT aerosols?
  7. krisbaum @ 104... And so you think that the large spacial distribution of CO presented in DB's gif is... bush fires? Maybe I've not been watching the news closely enough. Are there massive bush fires occurring in Beijing and Tianjin?
  8. @Rob 105 'Anthropogenic atmospheric aerosols are believed to be a significant climate forcing agent, probably second only to greenhouse gases in their effect on global temperature in the past century [Houghton et al., 2001]. However, the history of atmospheric aerosols is not nearly as well known as that of most gases because of the short atmospheric lifetime of aerosols and thus their very heterogeneous spatial distribution. Moreover, the climate effect of aerosols is complex, as some aerosols cause cooling while others are believed to cause warming.' page 3.
  9. Rob @107 - CO is not an aerosol.
  10. krisbaum @ 109... We are clearly not looking at the same paper. You said the title of the paper was, "Large historical changes of fossil-fuel black carbon aerosols." http://www.lbl.gov/Science-Articles/Archive/sb/July-2004/Historical-changes.pdf
  11. krisbaum @106, I explicitly referred you to the top center image for the discussion of aerosols. You will notice that it is labelled "AOT", standing for Aerosol Optical Thickness. There are certain minimum standards of conduct necessary for any rational discussion - honesty, consistent standards for your self and others, a willingness to cite relevant information etc. You have shown yourself consistently unwilling to abide by any such standard. Consequently my discussion with you is over. Until you undertake to show why it was reprehensible of the IPCC to cite Agassiz as the originator of the theory of ice ages; or to cite Newton's letter to Hooke in 1675 as the source of the famous quotation about standing on the shoulders of giants (two more of the supposedly dubious citations according to your favourite source), or admit that the quality of citations cannot be determined simply by looking at the immediate source and that your favourite source used a massively flawed methodology which is completely unable to justify the conclusions you, and they draw from it, there is nothing more to say.
  12. It is duly noted that krisbaum blatantly is ignoring the tasks he has given himself in 81 and 94. Just as he ignored the text description for the animated GIF found on the host page:
    "The animation below shows the fire activity and smoke plumes in Russia and China in June/July 2012 and the consecutive transport of smoke across the Pacific. The MACC GFAS assimilation of Fire Radiative Power observations are superimposed over the combined organic matter and black carbon fields in the MACC global aerosol assimilation, which combines the smoke emissions calculated in GFAS with inventories of anthropogenic emissions and aerosol optical depth observations from space. Both types of observations are performed by the satellite-based MODIS instruments and NASA has provided the observation data."
    Also note that aerosols travel enormous distances across continents and oceans. And note that they are not evenly-mixed or distributed, unlike CO2: [Source]
  13. Very interesting, there are actually two different versions of this paper. The one that krisbaum cites includes the sentence about short atmospheric lifetime, etc. The version I found was published in GRL specifically has that line deleted. It looks to me like kris is citing from (maybe) a pre-press version of the paper (?). I find it interesting that that line was removed.
  14. This has to be the most pointless discussion I've encountered in several years, and that includes the engagement with Tim Curtin at OM, the SLoT thread, and everything Dan H has started at RC. What will be the ultimate bottom line if krisbaum is correct in feeling misled by Pachauri? Would it mean anything where WG1, WG2, or WG3 are concerned? And although it's probably against comment policy, I'll wager krisbaum has no problem with (-Snip-), and those are much more damaging than anything Pachauri has to say about bloody grey literature (as one can see from the variety of mainstream media outlets that are seemingly plugged directly into WUWT).
    Response: [DB] Comments policy violation snipped.
  15. DSL does have a point. Krisbaum, the figure of 10km is not only arbitrary, it's also ludicrous and baseless. None of the papers you have referred to can allow to support this number. It is obvious you made it up on the moment to serve your argument. I see nothing in your various arguments that deseves any consideration and I'm done wasting my time on them.
  16. 'Greenland aerosol measurements tell you nothing, it is fairly common knowledge that aerosols do not travel far from their source typically 10km or so. You need localised measurements to get any kind of global pattern.' It is fairly obvious from recent discussions that my quotation above still applies, everbody is correct in disputing '10km' - as an arbitrary number like this, argue you may but the point still stands that (-Snip-).
    Response:

    [DB] It is very obvious from recent discussions that your quotation above is still invalid. The intercontinental reach & dispersion of aerosols has been amply demonstrated.

    Either finish your homework from comments 81 and 94 above or cede those points by declaring your position invalid.

    Off-topic diversion snipped.

  17. krisbaum, I'm not going to immediately discard your claim. I do, however, want to see some evidence. What you claim is not common knowledge. Here's a study that casts doubt on what you say just from the abstract. The study measures the 72 hour trajectory of a cloud of SO2 that extends 1600 meters from the surface. If the mass of SO2 travels for 72 hours and only goes 10km, that means it is traveling at the extremely fast rate of about 139 meters per hour. Possible, but not probable. This study worries about an oil refinery being built 30km away from the Taj Mahal and what the emissions will do to the structure. Why did they even perform the study? It's common knowledge that human-sourced aerosols only travel 10km. These were just two of the first few on google scholar. I can do more of your work for you if you require it.
  18. DSL; My original assertion about aerosols was to do with a lack of records pertaining to their levels - hence the high amount of high uncertainty in their values. [Anthropogenic] Aerosols are concentrated at their source and depending on their type (eg. Sulphates or Black Carbon etc) - they travel varied distances from their source but a geo-spacial representation of their concentrations in the atmosphere is required to estimate their impact on climate change.
    Response:

    [DB] Actually, your original assertion about aerosols was made here and was this:

    "Has anybody actually investigated further, for example the findings on Aerosols and why the IPCC believe what the range of aersol forcing is thats stated in their 4AR?"

    You did not make the assertion about aerosols that you claim until 4 ½ hours later, here.

  19. (-Snip-)
    Response:

    [DB] This has gone on long enough. As has been noted several times already, finish the work you have claimed for yourself in comments 81 and 94 above. You will be allowed no further podium to waste the time of others here until that work is completed.

    Argumentative and sloganeering snipped.

  20. [finish the work you have claimed for yourself in comments 81 and 94 above.] I just did and you deleted them.
    Response: [DB] Comments deleted were due to inflammatory/ad hominem comments and sloganeering. You continually focus on newspaper accounts of what Pachauri is reputed to have said. You continue to fail to show (from 81) where the IPCC has stated that it only bases its work on peer-reviewed literature. It is clear you posture.
  21. A final comment on the dispersion of sulfates. Fiedler et al, 2009 discuss the observation of a SO2 pollution plume just of the west coast of Ireland. That pollution plume came from China. In fact, it was not the only plume they found at that location. They found another, lower plume from North America as well, as shown in this diagram: You will notice the Chinese plume has approximately half the concentration North American Plume. Its greater altitude and thickness, however, suggests it would have greater than half the cooling effect of the North American plume. This suggests that it would make an appreciable impact on the atmospheric energy balance at that time and location. Below is a modeled distribution of Chinese SO2 based on known weather patterns at the time of observation. Again, notice that the concentration of SO2 in the plume is only around 40% of that over China, again signifying an appreciable impact on the energy balance: Despite the high concentration of the plume half way around the world, occurrences of plumes from China at that location would be sporadic, whereas the plume over China itself would be constant throughout the year. As a result, averaged over the year, concentrations over China would be large compared to those over the North Atlantic. But that in no way justifies Krisbaum's rather silly claims, and it certainly does not justify his supposition that SO2 concentrations in Greenland ice cores are a poor proxy of SO2 emissions over Europe and North America. As we have seen, there is no question that SO2 plumes can be carried more than half way around the world - let alone half way across the world's narrowest ocean to Greenland.
  22. Hi all,


    This may be a dumb question, but I'm wondering if someone could clear up my confusion about the rate of change in CO2 concentrations we're seeing today vs. the rate at which they've varied in the past.


    In this video, Michael Mann states that the rates today are changing a million times faster than what we've seen in the past, but this article above states that "atmospheric CO2 is increasing ten times faster than any rate detected in ice core data over the last 22,000 years."

    Thanks for your help,

    Andrew

  23. Woops, forgot the link: http://www.motherjones.com/blue-marble/2013/05/michael-mann-hockey-stick-climate-desk-live

  24. Tough to say, Andrewii.  While it's true that CO2 hasn't increased as rapidly as present in at least 300 million years, it would take some selectivity to make the math come out right on "1,000,000 times faster."  For example, we could find a period where CO2 advanced 120ppm over the course of 150,000,000 years.  Such a period might be found if one used the right analysis (e.g COPSE).  Then one could say, "We've put up 120ppm in 150 years, one million times as fast as in period x."  Or one could go the other route and find a much shorter period with a much more neutral trend. Without knowing the comparison period, it's hard to say what Mann is referring to.

    It's hard to be alarmist with the rate of CO2.  As Honisch et al. point out, it's possible there's no precedent for the current rate of increase.

  25. Andrewwii, when studying climate topics and associated facts, try not to view or read individual statements out of the larger context (note also that the video is pasted together from a longer one). It is easy to cherry-pick a single statement taken out of context and get confused by it, or even take it to mean somebody is dishonest or similar.

    In this particular case, we are talking about a rise from a preindustrial level of 280 ppm to today's 400 ppm in roughly 200 years (average 1.2 ppm per year, accelerating; currently 2 ppm/yr). In that video, Michael Mann refers to the last time the CO2 level was that high (several million years ago) and how much time it took then to change average levels by roughly as much (e.g. by 100 ppm), "10s of millions of years" (long-term average data here). Taking an average slope (ppm CO2 change over time) from that graph over the last 100 million of years gives roughly 10 ppm/million years ((1300-300) / 100), so about a 5th to a 10th of a million times as fast as today. If you take a shorter period, say only the last 30 million years, the slope is less, nearly matching what Mann referred to.

    So you see, it is easy to accuse him of saying something wrong. Human nature. It is more difficult though to stand back, look at the bigger picture, ask a clarifying question if possible, and avoid taking things out of context. So thanks for asking.

  26. andrewii

    This article discusses the findings by Lee Kump and colleagues wrt the rate of inctrease of CO2 during the Paleocene/Eocene Thermal Maximum, around 55 million years ago.

    PETM CO2

    This period is considered a reasonable analogue for today. The world was originally warmer than today by perhaps 4-6 DegC, then it experienced a doubling or more of CO2 very quickly (in geological time scales). Temps climbed another 4-6  DegC, a small Extinction event occurred and an Anoxic event occcurred in the ocean.

    Kump et al found that CO2 levels today are climbing 10 times faster than during the PETM.

  27. Thanks DSL, gws and Glenn Tamblyn!

  28. I'd like to suggest a subject for a future post:

    IPCC figures are virtually all limited to 2100. And all IPCC scenarios assume some emmission curbing at some point (ranging from slow to fast). That's unrealistally optimistic at this point, since there are no signs of leaving carbon reserves unexplored and buried undergound. They're even exploring new possibilities in hydrocarbons (like methane clathrate), and looking for new oil reserves (like in the Arctic).

    If we burn every reserve we know, this paper below projects a 16 ºC warming eventually, making "much of the planet uninhabitable by humans".

    "Climate sensitivity, sea level and atmospheric carbon dioxide"

    Hansen et al. 2013

  29. The reason the IPCC projections are necessarily conservative is that all participating countries have to agree on the information included!

  30. Hope this thread is appropriate.

    Over the years I've used the SKS escaltor in my blog posts from time to time.  Recently I recieved a reply "it is a great example of cherry picking noisy high/low points along a period when first the PDO and then the AMO moved into their positive phases. If you remove the noise then the escalator magically disappears. What's left is two step rises. The first from 1976-1980 was the PDO going positive. The 2nd from 1993-1995 was due to the AMO going positive.

    Response:

    [PS] Try here. Cherry picking by the way is making an argument by selecting only the part of the dataset that supports your argument. Real statistician have removed noise rigourously. See here. Sks escalator is that only deniers believe in step changes. The science shows that when internal variability is removed, then temperatures steadily rise with the increase in CO2.

  31. I've downloaded the 2018 IPCC report 

    Changes in Climate Extremes and their Impacts on the Natural Physical Environment https://www.ipcc.ch/site/assets/uploads/2018/03/SREX-Chap3_FINAL-1.pdf

     

    I've perused the References section and I can find no research that takes place later than 2011. I guess there's a possibility  the report is for 2013 but the link indicates that it's 2018 (No explicit mention of the date of the report in the text. Why?)

    If in fact it's 2018, why the delay in examining research?

  32. Cozumelito:

     From the title page of the report you cite:

    "This chapter should be cited as:
    Seneviratne, S.I., N. Nicholls, D. Easterling, C.M. Goodess, S. Kanae, J. Kossin, Y. Luo, J. Marengo, K. McInnes, M. Rahimi,
    M. Reichstein, A. Sorteberg, C. Vera, and X. Zhang, 2012:" my emphasis

  33. Take note that these are very large reports that take years to compile, write, and publish. Thus, the latest research will be several years prior to the published date of the final report.

  34. I believe the IPCC reports are probably the most used information to help set climate policy around the globe. However after reading this,

    http://climateextremes.org.au/wp-content/uploads/2018/08/What-Lies-Beneath-V3-LR-Blank5b15d.pdf

    and part of their summary :

    " Climate policymaking and the public narrative are significantly informed by the important work of the IPCC. However, IPCC reports also tend toward reticence and caution, erring on the side of “least drama”, and downplaying the more extreme and more damaging outcomes. Whilst this has been understandable historically, given the pressure exerted upon the IPCC by political and vested interests, it is now becoming dangerously misleading with the acceleration of climate impacts globally. What were lower-probability, higher-impact events are now becoming more likely. This is a particular concern with potential climatic tipping points — passing critical thresholds which result in step changes in the climate system — such as the polar ice sheets (and hence sea levels), and permafrost and other carbon stores, where the impacts of global warming are non-linear and difficult to model with current scientific knowledge.However the extreme risks to humanity, which these tipping points represent, justify strong precautionary management. Under-reporting on these issues is irresponsible, contributing to the failure of imagination that is occurring today in our understanding of, and response to, climate change. If climate policymaking is to be soundly based, a reframing of scientific research within an existential risk-management framework is now urgently required. This must be taken up not just in the work of the IPCC, but also in the UNFCCC negotiations if we are to address the real climate challenge. Current processes will not deliver either the speed or the scale of change required."

     

    So, i was wondering just how correct is this need to modify the scope of the IPCC reports. 

    " What Lies Beneath" put into words my feelings on our current  Aussie state - pretend we care but open more coal mines and do nothing..

    This video was also enlightening , a new documentary series , pt 1.

    https://www.breakthroughonline.org.au/#!

  35. prove we are smart @134,

    With one exception, I have only read the summary of the paper Spratt & Dunlop (2018) 'What Lies Beneath: The understanding of existential climate risk' which you refer to. In short, the need for action on AGW was demonstrated by the science over a quarter of a century ago yet globally our emissions increased as though no such science existed. There is now, policy-wise, an agreement that radical action is needed to prevent a +1.5ºC increase in global temperature, radical as such a goal requires global CO2 emissions in future years to be restricted to something like 120Gt(C). The general message from the science is that such a goal will prevent the very bad AGW effects from happening. Yet in terms of policy, there is still little urgency. The enthusiasm for declaring a Climate Emergency has not yet resulted in any useful policy but let us hope that it will, soon. Spratt & Dunlop (2018) suggest the 120Gt(C) is flawed but it seems to me that its argument would need to be far better presented to be a useful contribution.

    Their main criticism is that the science includes those "fat tails" which may make a +1.5ºC world a bit too hot to handle. There has been quite a bit of criticism of the IPCC for failing to make such potential outcomes better known. Most recently, Oppenheimer et al (2019) 'Discerning Experts: The Practices of Scientific Assessment for Environmental Policy' has described well instances of the IPCC's failings (three of the authors have an account of the book HERE). But while there are systemic problems within the IPCC assessments, they do not systematically underestimate AGW. There is perhaps need for the failings of the IPCC assessments to be better understood and in addressing that, I have no criticism of Spratt & Dunlop (2018).

    But Spratt & Dunlop (2018) goes further than this. There is a feel of this in their assessment of the impacts of AGW. Their Summary begins:-

    "Human-induced climate change is an existential risk to human civilisation: an adverse outcome that will either annihilate intelligent life or permanently and drastically curtail its potential, unless carbon emissions are rapidly reduced."

    The word "existential" is usually, in my view, very poorly wielded in regard to AGW. Here, the use "an existential risk to human civilisation" is refreshing to see. But then it is followed by "annihilate intelligent life" which is something I find very difficult to envision.

    So this got me delving into one further section of Spratt & Dunlop (2018). The section Carbon Budgets makes a number of points (♣ Not working other GHGs into the budget, ♣ Not evaluating "fat tails" which would reduce carbon budgets to zero, ♣ Relying on models that potentially run cool, ♣ Not defining pre-industrial temperature adequately, ♣ Ignoring actual peak temperatures) but I only see one of these issues that is germane to setting carbon budgets (the cool models). So for me, Spratt & Dunlop (2018) seems to be 'firing from the hip' a bit too much and needs to tighten up its message if they want to make a serious contribution.

  36. M A Rodger @ 135, i think shooting from the hip is exactly what the IPCC should be doing. With CO2 levels still increasing from the last three decades, taking slow aim and firing is just missing the target. Just how unprepared / misinformed are we in Australia? Look at this,      https://www.breakthroughonline.org.au/

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