Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Twitter Facebook YouTube Pinterest MeWe

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
New? Register here
Forgot your password?

Latest Posts

Archives

The Grumble in the Jungle

Posted on 29 October 2010 by Rob Painting

An article in a British newspaper claimed that the Intergovernmental Panel on Climate Change (IPCC) published wrong information about the Amazon Rainforest in their 2007 report. The issue centred on the statement that about 40% of the Amazon was susceptible to the effects of drought, or more specifically "slight reductions in rainfall".

The Amazon is the world's largest tropical rainforest, and due to its immense size, has a global effect on the Earth's climate. Despite being well adapted and resilient to wet and dry periods which occur throughout the year, the rainforest is vulnerable to extended periods of drought. Any major decline in the health of the Amazon rainforest is likely to impact the world climate.

The skeptic claims relate to section 13.4.1 of the IPCC Fourth Assessment Report (2007) which made the statement: 'Up to 40% of the Amazonian forests could react drastically to even a slight reduction in precipitation; this means that the tropical vegetation, hydrology and climate system in South America could change very rapidly to another steady state, not necessarily producing gradual changes between the current and the future situation' (Rowell and Moore, 2000)

The reference is to a non-peer reviewed report prepared by the World Wide Fund for Nature (WWF) which itself cites an original peer reviewed study (Nepstad 1999) as the basis for the claim. The citations in the WWF and IPCC reports are not complete, Nepstad 1994, Nepstad 1999 and Nepstad 2004 support the claim that up to half the Amazon rainforest were severely affected by drought. Further studies, carried out since the 2007 IPCC report, reinforce the Amazon's susceptibilty to long term reductions in rainfall .

The IPCC could have avoided confusion by simply citing the peer reviewed studies themselves, rather than the WWF report and perhaps "slight reduction" should have been better defined or qualified. Despite the error in citation, the statement made by the IPCC is factually correct. Maybe the last word should go to the lead author of the papers upon which the statements were based, Daniel Nepstad, who made a public press release to clear up the mainstream media confusion over the subject. Nepstad concludes:

"In sum, the IPCC statement on the Amazon was correct. The report that is cited in support of the IPCC statement (Rowell and Moore 2000) omitted some citations in support of the 40% value statement.

 This post is the Basic Version (written by Rob Painting) of the skeptic argument "IPCC were wrong about Amazon rainforests".

0 0

Printable Version  |  Link to this page

Comments

Comments 1 to 27:

  1. Great title, and great explanation, Rob! Much ado about nothing, like the Himalayan Glacier typo. The Yooper
    0 0
  2. And the terminology difference in the "how much of Holland is below sea level/river level/could be flooded". It would be nice of the MSM pointed out to people that indeed the Amazon forests are threatened, the glaciers are melting, Holland will be flooded. Instead of, I'm sure quite unintentionally, leaving the public with the impression that the report was "full of errors". Now don't anyone tell me it was intentional or I'll be left with no childish illusions at all (and I could have made a lot of money if the tooth fairy had been around in recent years, I can tell you).
    0 0
  3. Why are you reacting to an event that happened back in January? I can appreciate that it was a point that needed tackling. But it does seem odd that it has taken this long.
    0 0
  4. MikeCC - This is a basic rebuttal, one of a series adressing the skeptic arguments. Eventually all arguments will have a basic/intermediate/advanced version. It will take some time for this process to be complete. Hope that helps.
    0 0
  5. No problem for me, a great explanation, far better than I did when I was arguing the point at the time!
    0 0
  6. Interesting to see the following in the Guardian today Amazon drought leaves Brazil's Rio Negro dry http://www.guardian.co.uk/environment/gallery/2010/oct/26/amazon-drought-brazil#/?picture=368055072&index=7 Peter
    0 0
  7. Peter #6 - Indeed - the reality is being acted out on the ground! Good to see the refutations mounting up - this is already the best source for quick factual debunks and is improving all the time. Cheers - John
    0 0
  8. Would it not be better to cite the original article or at least the newspaper and date?
    0 0
  9. Ed Davies @8 It might be hard as the Times of London was forced to retract the original article by Jonathan Leake and pulled it from the web. There are of course many websites that site the article as truth despite the retraction. You'd barely know there was a retraction. Real Climate had a post on the retraction when it came out
    0 0
  10. Stephen Baines, thanks. Couple of points, though: 1. According to RealClimate it was the Sunday Times, not the Times. These are different papers though both are part of the Murdoch empire. 2. Just because the article has been retracted doesn't stop it being cited, though of course it might make it harder to link to. 3. The retraction is, though not strictly relevant to this post, of sufficient interest to be worth mentioning - particularly for those who come here via Google as a result of more recent citations of the article. Maybe instead of "An article in a British newspaper claimed..." it would better be "An article in the January 31st, 2010 edition of the British Sunday Times newspaper, subsequently retracted, claimed...". (I'm assuming here that the original publication date is the same as that given on the PDF linked from the RealClimate page.)
    0 0
  11. Yes, true,...the WWF document omitted some 'citations'. But the 'citation' omitted was to a now-defunct Brazilian website, which contains the passage. You have forgotten to mention that - a fact which only weakens the IPCC's case, if anything. Nepstad can offer his opinions to support the authors of the WWF document. How does that in any way, relate to what the IPCC did with its Amazon chapter?
    0 0
  12. Shub @11 - your comment doesn't make sense. The omitted citations, supporting the WWF document & the IPCC claim, are peer-reviewed literature. Nepstad was the lead author on those studies mentioned above.
    0 0
  13. Dear Rob The supposedly omitted citations - per Nepstad, who had no acknowledged hand in drafting the IPCC report chapter - do not support the claims made in the IPCC passage. Nepstad 1994, 1999 and 2004 are peer-reviewed, no doubt - the issue at hand is however not that.
    0 0
  14. The supposedly omitted citations - per Nepstad, who had no acknowledged hand in drafting the IPCC report chapter - do not support the claims made in the IPCC passage "In sum, the IPCC statement on the Amazon was correct." - Daniel Nepstad Could it be any clearer?
    0 0
  15. It is pretty clear, Rob. Only it is not correct. For the IPCC statement to be correct, the claim has to originate in peer-reviewed literature. It does not. In making a claim, it has to first originate and be grounded from a substantive source, and the reference cited for the claim should directly refer to that source - pretty basic stuff in science. The IPCC claim on the Amazon fails both tests. As it is evident, the basic premise of your article rests on taking Nepstad's word for it. These issues have been discussed at length, and at several venues.
    0 0
  16. For the IPCC statement to be correct, the claim has to originate in peer-reviewed literature. It does not And your stipulation originates from where exactly?. This from the IPCC AR4: "The Working Group II Fourth Assessment, in common with all IPCC reports, has been produced through an open and peer-reviewed process. It builds upon past assessments and IPCC Special Reports, and incorporates the results of the past 5 years of climate change impacts, adaptation and vulnerability research. Each chapter presents a balanced assessment of the literature which has appeared since the Third Assessment Report[1] (TAR), including non-English language and, where appropriate, ‘grey’ literature". The Amazon reference was within an AR4 Working Group 2 assessment, and the aforesaid "grey literature" is based upon peer-reviewed science. Sorry, but invoking the Chewbacca defense, is not part of a rational discussion.
    0 0
  17. Dear Rob, You say: "And your stipulation originates from where exactly?." I believe you do understand how these things work. If you claim that the Amazon statement is based "on peer-reviewed literature", and not just take Nepstad's word for it, it is incumbent on you to come up with the reference. I cannot prove a negative, i.e., I cannot show where the Amazon claim did not come from. Let me help. You say above (in post #12): "The omitted citations, supporting the WWF document & the IPCC claim, are peer-reviewed literature." This is incorrect. The WWF document reproduces text verbatim, from a website which is not working anymore. It omitted to cite the website. Both these sources are not peer-reviewed. If as you claim later down, these gray literature sources are based on peer-reviewed science, can you find them for us? Moreover, the IPCC claim is entirely different from what the WWF report makes. Ultimately, let us remember, it is the IPCC statement is what we are interested in. And lastly, the IPCC rules allow for appropriate gray literature only if no primary sources are available for any claim to originate from, or be substantiated by. Your point above #16, clearly shows the IPCC was in violation of its own rules. I liked your Chewbacca link. Pretty interesting. :)
    0 0
  18. If you claim that the Amazon statement is based "on peer-reviewed literature", and not just take Nepstad's word for it, it is incumbent on you to come up with the reference. Incumbent?. No not really. But read Nepstad 1994, 1999 & 2004. Links are provided above. The WWF document reproduces text verbatim, from a website which is not working anymore. Have you considered the website was copied from the actual report?. No?. The WWF document is linked to above, you'll find it was produced by the authors after consultation with a few "experts' including one Daniel Nepstad. See the acknowledgements section. these gray literature sources are based on peer-reviewed science, can you find them for us? See Nepstad papers above. Moreover, the IPCC claim is entirely different from what the WWF report makes. IPCC - "Up to 40% of the Amazonian forests could react drastically to even a slight reduction in precipitation" WWF - "Up to 40% of the Brazilian forest is extremely sensitive to small reductions in the amount rainfall And lastly, the IPCC rules allow for appropriate gray literature only if no primary sources are available for any claim to originate from, or be substantiated by........clearly shows the IPCC was in violation of its own rules Each chapter presents a balanced assessment of the literature which has appeared since the Third Assessment Report[1] (TAR), including non-English language and, where appropriate, ‘grey’ literature Which rule was violated?. Tell me, are you Richard North?.
    0 0
  19. Dear Rob, I have read Nepstad 1994, 1999 and 2004. They do not support the IPCC's claim. The website could not have been copied from the report because the report came after the website. The website in question, is extensively cited in the WWF report in several other contexts. Secondly, I reiterate, the IPCC and the WWF report claims are different - it is even evident in the small portion of the claim you have reproduced above. Thirdly, The IPCC rules for use of grey literature (found in Principles governing IPCC work) state that authors should critically evaluate grey literature and the requirement for its use in its reports. Additionally, it states the lead authors should archive a copy of any such material available for general use. The IPCC did not archive a copy of the website page. Moreover, the passage you quote, is not part of the rules (or governing principles) - it is just a description of its methods. And lastly, I am not Richard North. :)
    0 0
  20. Shub, have you read the Intermediate version of this argument ? There, you can read the following : The WWF correctly states that 630,000 km2 of forests were severely drought stressed in 1998 - this figure comes from Nepstad 1999. However, the 40% figure comes from several other papers by the same author that the WWF failed to cite. A 1994 paper estimated that around half of the Amazonian forests lost large portions of their available soil moisture during drought (Nepstad 1994). In 2004, new rainfall data showed that half of the forest area of the Amazon Basin had either fallen below, or was very close to, the critical level of soil moisture below which trees begin to die (Nepstad 2004). The results from these papers are consistent with the original statement that 'Up to 40% of the Brazilian forest is extremely sensitive to small reductions in the amount of rainfall' To really see the connection, you have to differentiate between "Amazonian forest", "Amazon basin" and "Brazilian forest".
    0 0
  21. I have read Nepstad 1994, 1999 and 2004. They do not support the IPCC's claim. Shub, Your posts thus far, (aside from the South Park - Chewbaccan logic) have consisted of taking your word over that of Daniel Nepstad. I find it notable that you never provide references for your claims. This is the internet remember? Anyone can write anything, which is why we prefer posters to provide legitimate references. Notice the difference between my posts and yours?. I've read Nepstad's papers, and a whole lot more besides, I agree with Nepstad. I'll recap, here's what Nepstad (a scientist who has studied the Amazon for decades) and the lead author of those cited studies had to say (from the link provided above): "The Rowell and Moore review report that is cited as the basis of this IPCC statement cites an article that we published in the journal Nature in 1999 as the source for the following statement: "Up to 40% of the Brazilian forest is extremely sensitive to small reductions in the amount of rainfall. In the 1998 dry season, some 270,000 sq. km of forest became vulnerable to fire, due to completely depleted plant-available water stored in the upper five metres of soil. A further 360,000 sq. km of forest had only 250 mm of plant-available soil water left.[Nepstad et al. 1999]" (Rowell and Moore 2000)" "The IPCC statement on the Amazon is correct, but the citations listed in the Rowell and Moore report were incomplete. (The authors of this report interviewed several researchers, including the author of this note, and had originally cited the IPAM website where the statement was made that 30 to 40% of the forests of the Amazon were susceptible to small changes in rainfall). Our 1999 article (Nepstad et al. 1999) estimated that 630,000 km2 of forests were severely drought stressed in 1998, as Rowell and Moore correctly state, but this forest area is only 15% of the total area of forest in the Brazilian Amazon. In another article published in Nature, in 1994, we used less conservative assumptions to estimate that approximately half of the forests of the Amazon depleted large portions of their available soil moisture during seasonal or episodic drought (Nepstad et al. 1994). After the Rowell and Moore report was released in 2000, and prior to the publication of the IPCC AR4, new evidence of the full extent of severe drought in the Amazon was available. In 2004, we estimated that half of the forest area of the Amazon Basin had either fallen below, or was very close to, the critical level of soil moisture below which trees begin to die in 1998. This estimate incorporated new rainfall data and results from an experimental reduction of rainfall in an Amazon forest that we had conducted with funding from the US National Science Foundation (Nepstad et al. 2004). Field evidence of the soil moisture critical threshold is presented in Nepstad et al. 2007. In sum, the IPCC statement on the Amazon was correct".
    0 0
  22. The website could not have been copied from the report because the report came after the website Well, you are correct on that point only (re-reading on my part), however the WWF report is as follows (link provided above): " Up to 40% of the Brazilian forest is extremely sensitive to small reductions in the amount of rainfall. In the 1998 dry season, some 270,000 sq. km of forest became vulnerable to fire, due to completely depleted plant-available water stored in the upper five metres of soil. A further 360,000 sq. km of forest had only 250 mm of plant-available soil water left. "(46) 46 = D. C. Nepstad, A. Veríssimo, A. A l e n c a r, C. Nobre, E. Lima, P. Lefebvre, P. S c h l e s i n g e r, C. Potter, P. Mountinho, E. Mendoza, M. Cochrane, V. Brooks, Large - scale Impoverishment of Amazonian Forests by Logging and Fire, Nature, 1999, Vo l 398, 8 April, pp505 Nepstad 1999?. I'm sure there a few copies of that lying around. See above. Secondly, I reiterate, the IPCC and the WWF report claims are different - it is even evident in the small portion of the claim you have reproduced above. I must admit, I've known for a while, where you were heading with that particular "gotcha". Ho-hum. See Nepstad's comments reproduced in my previous post @21. The IPCC rules for use of grey literature (found in Principles governing IPCC work) state that authors should critically evaluate grey literature and the requirement for its use in its reports From the IPCC principles appendix: Authors who wish to include information from a non-published/non-peer-reviewed source are requested to: a. Critically assess any source that they wish to include. This option may be used for instance to obtain case study materials from private sector sources for assessment of adaptation and mitigation options. Each chapter team should review the quality and validity of each source before incorporating results from the source into an IPCC Report. b. Send the following materials to the Working Group/Task Force Bureau Co-Chairs who are coordinating the Report: - One copy of each unpublished source to be used in the IPCC Report - The following information for each source: - Title - Author(s) - Name of journal or other publication in which it appears, if applicable - Information on the availability of underlying data to the public - English-language executive summary or abstract, if the source is written in a non English language - Names and contact information for 1-2 people who can be contacted for more information about the source. Critically assess, seems somewhat subjective don't you think?. Public availability doesn't seem an issue either. Could the IPCC have handled this better?. Absolutely, they should have simply referenced the peer-reviewed literature, for starters. The crucial issue is whether the IPCC statement on the Amazon susceptibility to drought is correct - it is. There's ample research carried out since the 2007 IPCC report that strengthens this view (to be covered in a later post) and as a matter of fact severe drought is currently affecting the Amazon: Drought strikes the Amazon rainforest again
    0 0
  23. Rob, We know this "is the internet", "chewbacca" etc etc - these types of statements will only derail any discussion, I could indulge in such things as well. So you are pretty sure Nepstad 1994, 1999 and 2004 contain material that can support the IPCC statement? Well, firstly observe the Nepstadian: "The IPCC statement on the Amazon is correct, but the citations listed in the Rowell and Moore report were incomplete". How do you read this? There is a clear switch here. This is important because Nepstad, for the remainder of his press release, basically defends and explains concepts set out in his papers, as they relate to the rudimentary form they were in, when formulated in 1998, in the website and copied out in the *WWF report*, not the IPCC WGII report. This does not concern our question, speaking strictly. However, since you and many other before, have fallen for this switch, it does not do any harm to point out more explictly that the Nepstad papers deal with putative soil-moisture deprivation driven thresholds for *fire risk* - a simple fact you have consistently managed to overlook all the while now. This rather limited formulation -'climate fire risk' stemmed from the mid-late 90s when the Indonesian tropical peat fires spurred many researchers to study forest fires and ecologic conditions that would cause massive forest fires. One pathway studied was trying to identify a 'critical soil moisture threshold' at which vast tracts of forest just burn away. The fact remains that, even after all aforesaid studies, no such single mythical threshold level exists or has been found, for tropical forests like the Amazon. The fire risk concept is distantly related to, but quite distinct in substance from the IPCC formulation, which speaks of "drastic change" without ever specifying what the "change" is, continues to talk about the whole "tropical vegetation, hydrology and climate system" of the entire continent of South America potentially changing "very rapidly to another steady state". If this difference between the two cannot be acknowledged or reconciled, the more straightforward thing would be to simple admit that the IPCC made a mistake by using WWF material, however vaguely similar the resulting claim may look, to results from other lines of enquiry. Nepstad 1999 estimates fire risk and damage from logging. Nepstad 2004 estimates amount of forest at risk for fires, using soil moisture as a guide. If soil moisture loss were to actually cause half of the Amazon system to burn away, the forest would be long gone. Important ecophysiologic mechcanisms keep such an eventuality from transpiring, a fact that Nepstad and colleagues acknowledge in more recent publications. The Amazon WWF error and the Himalayan WWF error have many things in common. Passages were copied bulk from WWF reports, but their meaning was appropriately modified to make them sound relevant to climate change regional impacts. In the case of the Himalayan error, the number 2035 became a focal point of highlighting the statement's erroneousness. The Amazon statement has no single similar focus - an opportunity that has been exploited by Amazon researchers to defend the IPCC and their own exlanations from scrutiny. But the error remains nevertheless, because if you extract a similar claim from the Nepstad papers, or any similar reference, for that matter - it would come out different from what is to be found in the IPCC. I would also draw your attention to what commenter Mikemcc pointed out - these issues have been examined and discussed in far greater detail, at RealClimate, Wattsupwiththat (a thread where Nepstad commented), Climateaudit and Roger Pielke Jr's blog where Dr Ranga Myneni, Boston University put forth his comments, and several other blogs, including my own. Secondly, in framing its principles, "non-peer-reviewed" literature for the IPCC primarily meant industry reports and private sector sources - as the IPCC illustrates with an example of accessing material for case studies. The IPCC either never anticipated the use of environmental pressure group literature in its reports, or does not wish to confront the problem of authors doing so. RK Pachauri's statements suggest the latter - he has repeatedly argued that, for many areas of study, no adequate peer-reviewed literature is available and that grey literature from any source not be treated "as if it was some form of grey muddied water flowing down the drains". The issue is pretty clear: authors are supposed to "critically assess any source", reviewing the "quality and validity of each source", before proceeding. The WWF report, and therefore the Amazon statement from the IPCC, violates all these governing principles. If you want to make a claim present in the primary literature, do just that.
    0 0
  24. We know this "is the internet", "chewbacca" etc etc - these types of statements will only derail any discussion, I could indulge in such things as well. Shub, if you are going to engage in such tactics, it's only fair for me to point this out to uninformed readers. So you are pretty sure Nepstad 1994, 1999 and 2004 contain material that can support the IPCC statement? No point in playing games, I've pointed out as much. However, since you and many other before, have fallen for this switch, it does not do any harm to point out more explictly that the Nepstad papers deal with putative soil-moisture deprivation driven thresholds for *fire risk* - a simple fact you have consistently managed to overlook all the while now. Shub, trees aren't made of asbestos, fire will kill them just as surely as drought. Pathetic looking low- level fires kill up to half of Amazonian trees they encounter, secondary fires almost double that mortality. You would know this if you had done done research on the subject. Putting forward this as some counter-argument is somewhat absurd. From Nepstad 2004: "This study points to the widespread effect of drought on Amazon forests, and the vulnerability of Amazon forests to small declines in rainfall or increases in ET(evapotranspiration). Rainfall and ET are nearly equal across the Amazon during most years, with total rainfall falling below ET during years of severe drought. Such droughts may become more common if ENSO events continue to be frequent and severe, if rainfall is inhibited by deforestation or smoke, and if warming trends continue. Increases in ET of only 15% or similar reductions in rainfall can lead to severe soil moisture deficits over roughly half of the Amazon (Fig. 9)The increase in forest flammability associated with severe drought poses one of the greatest threats to the ecological integrity of Amazon forests."

    0 0
  25. One pathway studied was trying to identify a 'critical soil moisture threshold' at which vast tracts of forest just burn away. This is a strawman argument. The decline in soil moisture will not necessarily lead to vast tracts of the rainforest simply burning away. The response is likely to be complex and not necessarily homogeneous over the whole region. The rainforest itself has significant influence over hydrology in the region, affecting rainfall distribution, cloud formation, altering soil structure, water storage capacity, surface solar radiation and lowering surface temperatures. Increased seasonality (i.e a drier dry season, and a wetter wet season) can kill trees, despite only a small change in annual rainfall. Increased fire risk, is but one of a number of negative consequences. The fact remains that, even after all aforesaid studies, no such single mythical threshold level exists or has been found, for tropical forests like the Amazon. Well, actually studies have identified a range of moisture thresholds for the rainforest. Think about it for a moment, what limits the current extent of rainforest in the Amazon?. Don't you suppose soil moisture might be a limiting factor?. If you are implying that one single threshold exists for all rainforests, that seems unlikely given the varied conditions. If soil moisture loss were to actually cause half of the Amazon system to burn away, the forest would be long gone Sorry, but again, strawman material. The Amazon WWF error and the Himalayan WWF Please stay on topic. And again I've amply demonstrated the IPCC statement is correct. The word "error" used here is simply an opinion, and one contrary to established research. these issues have been examined and discussed in far greater detail, at RealClimate, Wattsupwiththat....... Well it appears, not well enough, given your misunderstanding of the topic. And it might just be my interpretation, but that appears some kind of appeal to authority. If so, color me unimpressed. The WWF report, and therefore the Amazon statement from the IPCC, violates all these governing principles. Again, just your opinion. I've reproduced the relevant guidelines above. People can make up their own minds, they don't need you as some sort of arbiter of the written word. Really beside the point anyway, I've already stated the IPCC could have handled this better, the issue is whether the statement is correct. It is.
    0 0
  26. The decline in soil moisture will not necessarily lead to vast tracts of the rainforest simply burning away. The response is likely to be complex and not necessarily homogeneous over the whole region. I said - "One pathway studied was trying to identify a 'critical soil moisture threshold' at which vast tracts of forest just burn away" - and this is a statement, not an argument. This statement simply places in context the earlier papers from Nepstad - 1994, 1999, 2002 and 2004. The Nepstad papers study precisely this very concept of fire risk and nothing more. All the expected complex changes that you list, are not examined by the Nepstad papers, but the IPCC statements refers to them - which was my point to begin with. Think about it for a moment, what limits the current extent of rainforest in the Amazon?. It is not me, who is implying a single threshold - it is researchers such as Nepstad have studied looking for such a threshold. Such 'thresholds' do exist, if you can at all call them that, but they arrive after years of soil moisture deprivation under artificial drought conditions, not just with 'a slight reduction of rainfall'. I would ask you to think about it for a moment - why would half the forest 'react drastically', to 'even a slight change in rainfall', as unsubstantiated as that may be, if you believe that the system response 'likely to be complex', 'not necessarily homogenous', given 'the varied conditions'? Lastly, I pointed you to the sources above, because the questions and issues being discussed were put to Nepstad himself, whom you quote extensively. Roger Pielke Jr discussed the issue at Climateaudit, following which he wrote a post, which has since been picked up and quoted. These are folks who either support the IPCC or are outside parties to the Amazongate debate. It could assist in breaking out of the circularity of your claims Thanks
    0 0
  27. One pathway studied was trying to identify a 'critical soil moisture threshold' at which vast tracts of forest just burn away" - and this is a statement Yes, a strawman one. Nepstad papers study precisely this very concept of fire risk and nothing more. So let's get this straight, because the studies did not specifically set out to determine drought sensitivity itself, uncovered this anyway, but it doesn't count because they didn't set out to study it?. Is that what you are saying? It is not me, who is implying a single threshold Well it appears that way. Ecologists understand local conditions do vary within the Amazon. Some regions receive more rainfall than others, water table heights vary. The threshold exists over a range of values of precipitation. Such 'thresholds' do exist, if you can at all call them that, but they arrive after years of soil moisture deprivation under artificial drought conditions, not just with 'a slight reduction of rainfall'. Yes, I would call them thresholds, given that's the term used in the scientific literature. And no, the threshold has not been established using only data from the through-fall exclusion experiments (though they've proven very useful). I would ask you to think about it for a moment - why would half the forest 'react drastically', to 'even a slight change in rainfall', as unsubstantiated as that may be, if you believe that the system response 'likely to be complex', 'not necessarily homogenous', given 'the varied conditions'? Simply because the Amazon is (or maybe was) a system in equilibrium. The local vegetation exerts profound influence on water recycling and nutrient recycling. "If" a threshold is crossed it will lead to chain reaction, a series of positive feedbacks which cause it to "react drastically". A later post will address this, as understanding of ecology doesn't get much coverage on climate blogs, and it's an important aspect to consider. Roger Pielke Jr discussed the issue at Climateaudit, following which he wrote a post, which has since been picked up and quoted. These are folks who either support the IPCC or are outside parties to the Amazongate debate. Thanks, but I always do my own research. I'd rather not rely on the opinions of others (skeptic or non-skeptic), but on the peer-reviewed studies themselves. I also think you are ill-informed if you consider Pielke Jr etc, outside the debate.
    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



The Consensus Project Website

THE ESCALATOR

(free to republish)


© Copyright 2022 John Cook
Home | Translations | About Us | Privacy | Contact Us