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Up is Down, Brown is Green (with apologies to Orwell)

Filed under: — eric @ 15 March 2010

In the alternate universe of Fox News, Anthony Watts, and many others, up is down. Now, it appears, brown is green. Following the total confusion over the retraction of a paper on sea level, claims of another “mistake” by the IPCC are making the rounds of the blogosphere. This time, the issue is the impact of rainfall changes on the Amazon rainforest.

A study in 2007 showed that the forest gets greener when it rains less. A new study, by Samanta et al. in Geophysical Research Letters shows that the earlier work was flawed. Aided by an apparently rather careless press release, this is being used as evidence that the Amazon is less sensitive to rainfall changes than the IPCC claimed. But the Samanta et al. paper actually does not address the central questions at all. It only addresses whether a single anomalous rainfall year had an impact that is measureable and interpretable from a satellite sensor. The conclusion is that they could not detect a change. As noted in a commentary from Simon Lewis, University of Leeds, “the critical question is how these forests respond to repeated droughts, not merely single-year droughts.”

Lewis – a broadly published expert on tropical forests – makes a number of additional important points in his commentary below. Bottom line: IPCC gets it right as usual.

—————
Guest Commentary by Simon Lewis, University of Leeds, UK

The new Samanta et al. study uses sensors on satellites to assess the colour of the rainforest canopy in the dry season of the year 2005, compared to the dry seasons of the years 2003 and 2004. More detected green colour in 2005 may suggest that the forest is being more productive (more green leaves photosynthesising), or more brown colours may suggest leaves dying and less productivity, than the previous years. The results show that 2005 was little different to the previous years, despite the strong drought.

This is important new information, as in 2007, a paper using broadly the same satellite-based method showed a strong ‘greening-up’ of the Amazon in 2005, suggesting tolerance to drought (Saleska et al. 2007, Science). The new study shows that those results were not reproducible, but also highlight the extreme caution that should be attached to satellite studies generally in this field, with instruments in space collecting data which is then used to infer subtle changes in the ecology of tropical forests.

In contrast to the 2007 paper, Oliver Phillips, myself, and others, published a paper in Science last year, using ground observations from across the Amazon, showing that while the 2005 drought did not dramatically change the growth of the trees compared to a normal year, as Samanta et al. also show, the deaths of trees did increase considerably. The new study of Samanta et al. does not contradict the Phillips et al. study, which itself shows the Amazon is vulnerable to drought via impacts on tree mortality. The Phillips et al. paper showed that remaining Amazon forest trees changed from absorbing nearly 2 billion tonnes of CO2 from the atmosphere annually over recent decades, as tree growth has been exceeding mortality, to being a large, but temporary, source of over 3 billion tonnes, from the elevated tree mortality associated with the 2005 drought event.

The evidence for the possibility of a major die-back of the Amazon rainforest is due to two factors,

1. That climate change induced decreases in rainfall in the dry season occur, and

2. The trees cannot tolerate these reductions in rainfall.

The Samanta paper does not directly address the first point; this is addressed using global circulation models (of which some, but not all, show a strong drying trend for the east of the Amazon over the 21st century). The second point is only addressed in a limited way. The critical question is how these forests respond to repeated droughts, not merely single-year droughts. The forests are of course able to withstand these single droughts (otherwise there would be no rainforest!) — it is their ability to survive an increased frequency of the most severe droughts that is critical to answer. Drought experiments, where a roof is built under the forest canopy to reduce rainfall, show that most forest trees survive a single year’s intense drought, in agreement with the ground observations in the 2005 drought, but can’t persist with repeated years of drought. The Samanta study does not address this point at all.

In conclusion, the new Samanta et al. study lends further weight to the emerging picture of the impact of the 2005 drought: that tree growth was relatively unaffected, but tree mortality increased, contributing temporarily to accelerating the rate of climate change, rather than as usual reducing it, via additions of carbon to the atmosphere from the dead trees. The mortality was far from catastrophic, but the impact on the carbon cycle was globally significant. This is hardly the ‘no impact’ of the 2005-drought on the forest suggested in various news reports.

I should add that there is considerable uncertainty associated with the models suggesting decreases in rainfall, and uncertainty as to how Amazon forests may react (especially when one considers the impacts of deforestation, logging, and fire combined with climate change impacts). But this uncertainty is being chipped away at by scientists, a task in which the Samanta et al. paper assists.

Oddly, the Boston University press release to accompany the paper was titled, “New study debunks myths about Amazon rain forests”. The opening line runs: “A new NASA-funded study has concluded that Amazon rain forests were remarkably unaffected in the face of once-in-a-century drought in 2005, neither dying nor thriving, contrary to a previously published report and claims by the Intergovernmental Panel on Climate Change.” So, have scientists, myself included, been peddling myths? Have respected journals being publishing them? Have the IPCC? The answer is no, no and no.

The reality is that the IPCC have largely ignored the papers on the model results of decreasing rainfall in the east of the Amazon, and the diverse evidence used to assess the sensitivity of these forests to such rainfall reductions. There are a couple of lines in IPCC Working Group I (“New coupled climate-carbon models (Betts et al., 2004; Huntingford et al., 2004) demonstrate the possibility of large feedbacks between future climate change and vegetation change, discussed further in Section 7.3.5 (i.e., a die back of Amazon vegetation and reductions in Amazon precipitation).”). And in Working Group II there is a now infamous single sentence:

“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 statement is not as carefully worded as it should be, and incorrectly referenced, but basically scientifically correct and defensible with recourse to the peer-reviewed literature available at the time. Rainforest persists above a threshold of rainfall, below which one finds savanna. If this threshold is crossed a landscape dominated by rainforest can ‘flip’ to savanna. Therefore a ‘slight’ reduction can lead to a ‘dramatic’ reaction. Of course, evidence of a shift to a new lower rainfall climate regime is needed, and evidence of large areas of forest close to that rainfall threshold would be required for the IPCC statement to be reasonable; there is ample published evidence for both.

Overall the conclusions in the IPCC 2007 Fourth Assessment Report are strengthened (because the anomalous result of the Saleska et al. 2007 paper appear to be at fault), not weakened, by the new Samanta et al. study as their press release implies.

Update: Saleska responds, pointing out that a) their 2007 paper is not contradicted by Samanta et al. (2010); b) nor is the IPCC report weakened by either paper. Confused? Then read what he has to say: here.


235 Responses to “Up is Down, Brown is Green (with apologies to Orwell)”

  1. 51

    It may be “obvious” to Gilles (@45) that the use sugarcane for ethanol is linked to deforestation–but is the “obvious” true?

    Not according to this:

    http://www.mongabay.com/brazil.html

    A substantial discussion of the issue–and biofuel production doesn’t even make the list.

    How can that be? Well, according to Wiki:

    “In 2008 Brazil has 276 million hectares of arable land, 72% use for pasture, 16.9% for grain crops, and 2.8% for sugarcane, meaning that ethanol is just requiring approximately 1.5% of all arable land available in the country.[61]”

    http://en.wikipedia.org/wiki/Ethanol_fuel_in_Brazil

    The underlying citation, for fact checkers (who read Portugese!):
    “Produção de álcool e de açúcar baterá recorde em 2008, prevê Conab” (in Portuguese). Folha de São Paulo. 2008-04-29. Retrieved 2008-11-09.

  2. 52
    Nick Gotts says:

    So we have the first weird result that the more uncertain the models are, the more action is needed. – Gilles

    That’s not “weird” at all. In a situation where we have excellent grounds for expecting disruptive changes to occur as a result of our activities, greater uncertainty concerning the scale of these changes of course mandates greater caution.

    Now what do you think would be the result of a reduction of fossil fuels? a diminishing, or an increasing pressure on biomass ? biomass is the only source of carbon apart from fossil fuels. Brazil is the main producer of biofuels, through sugar cane, and this needs land. So the result is rather obvious to predict – and does not rely on uncertain GCM, but simple and basic logics and sense of reality. Very weird, indeed…

    Pressure on the Amazon results primarily from cattle ranching, growing soybeans for cattle feed, logging for timber, mining, and subsistence agriculture. While oil palm plantations are a significant cause of deforestation in south-east Asia, the oil is used almost entirely for food, not biofuel. In short, tropical forest protection is a matter of political will; if this is not present, they will be destroyed, irrespective of whether we attempt to reduce fossil fuel use – because it is highly profitable to destroy them. The attitude behind this destruction is exactly the same as you are advocating – maximise profit and economic growth at any environmental cost.

  3. 53
    Completely Fed Up says:

    “The IPCC claim is wrong, and trying to relate that to the more extreme situation is incorrect.”

    And the papers and proofs of this error are where..?

  4. 54
    EL says:

    My absolute favorite spin today:

    http://www.americanthinker.com/2010/03/logical_positivism_and_the_ipc.html

    I must say, this article is the largest abuse of Godel that I have ever laid eyes on.

  5. 55

    This seems to be another case of what Andrew Revkin calls “journalistic whiplash” many times, relatively recently on 13 January at http://dotearth.blogs.nytimes.com/2010/01/13/climate-whiplash-in-the-greenhouse/ . The problem can be summarized, with the words of Kenneth Caldeira quoted in the Dot Earth article: “the press’s tendency to make a big story out of every individual paper, rather than reporting the picture that emerges out of the findings of a field of science over time”.

    p.s. Eric, do the name “Salenta” which appeared twice in your response to comment #31 actually mean “Samanta”?

    [Response: Fixed, thanks.--eric]

  6. 56
    Gilles says:

    ““In 2008 Brazil has 276 million hectares of arable land, 72% use for pasture, 16.9% for grain crops, and 2.8% for sugarcane, meaning that ethanol is just requiring approximately 1.5% of all arable land available in the country.[61]”

    Yes, to power around 10 millions cars. How many are to be powered in 50 years? I’m talking about increased pressure. And biofuels are not the only commodity when biomass is needed to replace fossil carbon.

  7. 57

    @13 John Peter wrote:

    “Surely you can find a way to make the full paper available on the internet with a new reference. It is really worth it.”

    and Gavin replied:

    http://www.americanscientist.org/issues/feature/2010/1/carbon-dioxide-and-the-climate/1

    The HTML version at the URL above is the only version with all the original text from the 1956 Plass article. The PDF was made from the version that was printed in the paper edition, which was elided based on suggestions from Gavin. (Note: Gavin’s commentary is included in full in both versions.) We failed to anticipate that people would purchase the PDF expecting to see the long version, for which I apologize. We would be happy to refund your money.

    David Schoonmaker
    editor
    American Scientist

  8. 58
    Spencer says:

    Not entirely off-topic: an open letter from US scientists proposing, among other things, that the IPCC establish a website where errors in reports can be acknowledged and claims of errors that are themselves incorrect can be refuted in “internet time”. This is what realclimate has been trying to do all by itself, and how great it would be if the IPCC would take up the idea! But would it be lively and readable, or bogged down in negotiated bureaucrat-speak?

  9. 59
    Gilles says:

    “That’s not “weird” at all. In a situation where we have excellent grounds for expecting disruptive changes to occur as a result of our activities, greater uncertainty concerning the scale of these changes of course mandates greater caution.”

    For me, greater uncertainty is not an “excellent ground for expecting disruptive changes”, but maybe it’s only a question of philosophy.

    But actually, I would say that your kind of position makes my warnings about the potential danger of reducing fossil fuels still more relevant : in the same spirit, the greater the uncertainty on the potential drawbacks of reducing fossil fuels is , the more cautious we should be before reducing them.I’m aware that this could appear as a paradox, but the paradox is from the beginning in the precautionary principle : uncertainty can go in both directions, and doesn’t really help to determine which is the best one to take.

  10. 60

    The contents of the press release are not remotely supported by the publication.

    It is clear that the political process is much more concerned about press releases than about the underlying work. Consider the McLean/de Freitas El Nino paper and its subsequent spin.

    http://deepclimate.org/2009/07/30/is-enso-responsible-for-recent-global-warming-no/

    The relationship between scientists and their respective press offices is no longer the trifling matter that many scientists would be inclined to expect, if indeed it ever was so.

    As matters stand Dr. Samanta or someone claiming to be him (did RC verify it was him?) stands by the press release. This thus becomes less of a process issue; we do not need to establish how this nonsense got past the press office if Samanta is willing to say he approves it. Assuming the attribution is correct, it now becomes Dr. Samanta’s responsibility to defend the argument implied in his comment #27 above, which is hardly less tendentious than the press release.

    The IPCC WG II comment that “up to 40% could react drastically” simply expresses a concern. There is no implication of certainty; indeed it implicitly states that “at least 60% is unlikely to react drastically” which could be taken as reassuring. In any case it would be difficult to refute.

    As has been discussed at length in the parent article and the comments, the quoted research does not constitute a refutation of that position in the slightest, but rather is a detailed refutation of the contrary and counterintuitive paper by Aragao et al that seemed to claim that rain forests love drought. This is a case where you don’t need a weatherman to say which way the wind blows. If tropical rainforests were so fond of drought, they would be growing in dry places. However, Samanta et al did the service of refuting Aragao.

    It is far from obvious how Samanta disputes Rowell or the IPCC. Many of us who have taken a first look at the matter believe that it does not.

    A couple of additional points remain to be resolved here. How did a press release which is perfectly attuned to what the doubt merchants might want it to say, and almost perfectly tangential to the actual results of the study, come out of the press office? This, it seems to me, remains a matter for the university to investigate.

    Second, it is important to note that if a paper were to come out that actually did refute Rowell 2000, it would not constitute any indication of a flaw in the IPCC process, nor an error in any sense. Questioning the conclusions of IPCC is necessary, else the first report would suffice.

    Science progresses. The idea that a refinement or even a reversal on a particular point in the consensus report constitutes evidence that the consensus process is flawed is hopelessly pernicious. It puts science in a perfect bind.

    But we need to cross that bridge in cases where the science has actually progressed. The distinction between a one-year drought and a persistent decline in precipitation ought to be obvious to a person working in the field. It is less obvious to the rest of us. If there is a case to be made, it was not made in the peer reviewed publication, but rather only in the press release.

    I have not been alone in spending a lot of time worrying over the badly damaged links between science and the press and writing about it. But so far as I know, little has been written about the connection between scientists and the institutional press offices that are supposed to serve scientists. The Samanta et al story makes it clear that this relationship can’t be taken for granted.

  11. 61
    Tom S says:

    [edit]
    The problem with the IPCC was not specifically with the data itself (which does appear flawed anyway), but that it was another case of the IPCC clearly using very questionable sources for their “peer reviewed” conclusions.

    [Response: You are confusing several different things; the IPCC didn't particularly rely on the Saleska et al. study; I don't think it is even cited.]

  12. 62
    Ike Solem says:

    Giles: “Yes.. if the enhanced mortality is not compensated in the next years by an increase of CO2 absorption, which is quite possible if old dead trees are replaced by new growing ones.”

    Is that a line from the CEI “CO2: We Call it Life” campaign? Global warming is good for you? CO2 is Nature’s Fertilizer?

    Again, look at the Canadian pine forest case. Has there been a spurt of new growth? Or are the underlying ecological factors taking over?

    Researchers with Natural Resources Canada agree historically frigid Canadian winters have kept the mountain pine beetle at bay, but the past decade hasn’t produced cold enough temperatures to kill off the insects. A winter low of -40 C for a sustained period or a sudden cold snap in early fall or late spring of -25 C is needed to end the outbreak, but mild winters have decreased the winter mortality rate from the usual 80 percent to less than 10 percent.

    Because of the reduced wood supply, forest companies have laid off thousands of workers, mills have closed and government officials are scrambling to figure out how to deal with the crisis. Fears are now mounting in the neighbouring province of Alberta, where a battle is mounting to prevent the eastward expansion of the beetle.

    The worry of both the pulp and paper industry and conservationists is that the pest will spread east on a diet of jackpine, a close relative of the lodgepole pine, as the beetle has shown a taste for it. Billions of jackpine trees are at risk, as their boreal forest home stretches across a massive northern eco-region from Alaska to Newfoundland.

    Could persistent Amazon drought, like persistent warm subarctic temperatures, lead to similar unforeseen effects?

    The main historical and present cause of deforestation in the Amazon is the expansion of cattle and soy production for export to European, Japanese and American markets, by the way. If sugarcane has any impact, it’s in the Cerrado region to the south – and again, it’s a minor constituent. This is probably why the IPCC head made the comment about how eating less meat would reduce deforestation-linked carbon emissions.

    But what is this, Giles, running with three myths at once? Biofuels are an ecological nightmare, fossil fuel CO2 promotes plant growth, and global warming is just a temporary blip due to natural variation – is that what you want people to believe?

  13. 63
    Hank Roberts says:

    Leonard, there’s a slight decrease in rainfall every time the clouds blow on by and the sun comes out. You’re confusing weather and climate.

    The IPCC report wasn’t written to avoid every possible intentional misreading.
    Please do better, we _need_ competent smart critics, not debate rhetoric.

  14. 64
    Andreas Bjurström says:

    Eric, can you give substantive evidence that Pielke usually don´t have substantive evidence for his claims? (this is a fair intellectual request)

    From reading Pielkes blog, I would say that he are fairly good at giving substantive evidence by quoting other scientists, high-lighting certain sentenses, analyzing what they are saying, arguing stringently for his claims, etc. That is the scientific method (of the social scinces) at work. Everyone is also free to comment at his blog, without censorship. What more can you ask for?

    My impression (besides the general picking and power struggle among researchers that want to be influential) is that the basic issue here is that scientists don´t like that other scientists (that are not close peers, i.e. that don´t belong to the right tribe) are critically analyzing that they are doing. Politicians are always scrutinized by the media and democracy demand that,whereas researchers demand iwory towers.

    [Response: Give me a break. Repeating false claims by others about plagiarism, and making up claims himself about plagiarism doesn't count? How about going on an on about the 'hidden agendas' of scientists, such as (most recently) Jane Lubchenko? One thing I'll agree with you about: Pielke Jr. is good at "high-lighting certain sentences" to give a particular (often false) impression of what is actually going on. I am happy to receive fair criticism. It is innuendo and lies I have trouble with. There is actually a difference bewteen these you know.--eric]

  15. 65
    Reasonable Observer says:

    I am glad to see Dr. Lewis posting on this subject. We had a big back and forth on this a couple of weeks ago so it is helpful to have the expert posting here.

    Dr. Lewis says:

    “Rainforest persists above a threshold of rainfall, below which one finds savanna. If this threshold is crossed a landscape dominated by rainforest can ‘flip’ to savanna. Therefore a ’slight’ reduction can lead to a ‘dramatic’ reaction. Of course, evidence of a shift to a new lower rainfall climate regime is needed, and evidence of large areas of forest close to that rainfall threshold would be required for the IPCC statement to be reasonable; there is ample published evidence for both.”

    This seems reasonable.

    So what percent reduction in rainfall would cause 40% of the Amazon to shift to savanna?

    Since you note earlier in your post that their is considerable uncertainty, maybe you could even give us a range.

    Something like: A reduction in rainfall of between X% and Y% would cause 40% of the Amazon to shift to savanna.

    Alternatively: A slight reduction is rainfall (5%), would cause between X% & Y% of the Amazon to shift to savanna.

  16. 66
    Paul Gosling says:

    The switch from CO2 uptake to production in 2005 seems much more likely to be a response of the soil to drying than decay of the dead trees, whih presumably take several years to decay, even in a wet (but then dry) climate.

  17. 67
    Jim Galasyn says:

    Dappled Water mentions the Amazon Rainfall Exclusion Experiment. More here at the Woods Hole site: Drought Simulation.

    Another surprise was that the observed sensitivity of large canopy trees to drought is greater than expected. Once the moisture that is stored in deep soil is depleted, the largest trees – towering 130 to 150 feet above the ground and basking in full sunlight – begin to falter and die.

  18. 68
    Nick Gotts says:

    “That’s not “weird” at all. In a situation where we have excellent grounds for expecting disruptive changes to occur as a result of our activities, greater uncertainty concerning the scale of these changes of course mandates greater caution.” – Me

    For me, greater uncertainty is not an “excellent ground for expecting disruptive changes”, but maybe it’s only a question of philosophy. – Gilles

    I think in this case it will be clear to everyone that you are deliberately twisting what I said. I did not say that greater uncertainty is an excellent ground for expecting disruptive changes, as is quite evident from your quote from me. The fact that you are unable to make a case without this sort of distortion is extremely telling.

    I would say that your kind of position makes my warnings about the potential danger of reducing fossil fuels still more relevant : in the same spirit, the greater the uncertainty on the potential drawbacks of reducing fossil fuels is , the more cautious we should be before reducing them. – Gilles

    Indeed, uncertainty works both ways, but there are a number of differences. First, there are additional grounds for reducing fossil fuel use, which you yourself have noted: the supply of such fuels is finite, and in the case of oil, probably quite limited. Second, there are large differences even between rich countries in the amounts of fossil fuels used, and many ways in which use can be reduced by increasing efficiency: hence we have good grounds for believing that considerable reduction is possible without adverse effects. Third, so far as the use of electricity is concerned, we already have alternatives, and we know that much of the electricity-producing plant will in any case need to be replaced in the relatively near future. Fourth, reducing fossil fuel use is readily reversible; changing the composition of the atmosphere is not.

  19. 69
    Hank Roberts says:

    One hit on Saleska (2003) in Ch.7, in discussing the available studies, the uncertainties, and the need for large scale study to determine trends:

    “… the recent pan-tropical warming, about 0.26°C per decade (Malhi and Wright, 2004), could increase water stress and respiration, and stimulation by CO2 might be limited ….
    … studies involving large-area plots (9–50 ha) have indicated either no net long-term change or a long-term net decline in above ground live biomass (Chave et al., 2003; Baker et al., 2004; Clark, 2004; Laurance et al., 2004), and a five-year study of a 20 ha plot in Tapajos, Brazil show increasing live biomass offset by decaying necromass (Fearnside, 2000; Saleska et al., 2003).
    Koerner (2004) argues that accurate assessment of trends in forest carbon balance requires long-term monitoring of many replicate plots or very large plots; lacking these studies, the net carbon balance of undisturbed tropical forests cannot be authoritatively assessed based on in situ studies….”

    That’s why we’re seeing so many satellite color interpretation studies–it’s far less expensive, if and when the satellite data can be reliably established as showing something specific is going on on the ground. But this is one of those “need to run old and new system in parallel” problems so beloved of beancounters who just want to throw out the old and start up the new and trust in luck. Getting enough data to _know_ what the satellite data sets reflect takes serious ground work for a while.

    A different study (2005) on which Saleska is a coauthor is cited in Ch.13

    http://www.google.com/search?hl=en&q=site:ipcc.ch+saleska

  20. 70
    Nick Gotts says:

    My impression (besides the general picking and power struggle among researchers that want to be influential) is that the basic issue here is that scientists don´t like that other scientists (that are not close peers, i.e. that don´t belong to the right tribe) are critically analyzing that they are doing. – Andreas Bjurström

    Well, “impressions” differ. Mine is that scientists resent pseudo-scientists making extravagant claims on a basis of ignorance; and that the latter are themselves extremely touchy in response to critical analysis.

  21. 71
    Eli Rabett says:

    Eric, you are infantilizing Prof. Samanta, and setting yourself (and us) up for a beating. As you may have noticed, the climate debate is NOT being played out in the scientific literature and there are a fair number of nasty people out there gunning for you and your colleagues. Pretty much anyone can spin a clear statement into a CYA garment. Either Samanta knew what he and his colleagues were doing in that press release, in which case as Dr. Lewis has shown, he was culpably wrong, or he was unbelievably naive, in which case he still is wrong and needs not to post on Real Climate, but in the places where his paper is being used as a club against the IPCC. Eli makes no assumption about motives, but he understands responsibility and effects.

    In the words of Daniel Patrick Moynahan, if you define deviency down, you get devients. A large proportion of the mess we find ourselves in is owed to your (climate scientists) willingness to listen to excuses in private from the Lindzens and the Pielkes, while they read you out in public. Samanta has taken the first bite, either the cost is made clear to him, or he will take the second.

  22. 72
    Hank Roberts says:

    Oh, and for “reasonable observer” — you’re asking for a prediction in advance of the facts needed, while many links here could inform you of the work going on. We know this kind of flip happens — from the paleo record; at some level of decrease in rainfall/availability of groundwater, forests are replaced by grasslands. But that’s a gross oversimplification–it describes the change in the rock layers! The details, in living systems, are just now being looked at.

  23. 73

    A remark to the comment by Michael Tobis (#60) which I generally agree.
    The paper which claimed counterintuitive greening is not by Aragao, but by Saleska et al. The paper by Aragao et al. mentioned more biomass fires during the drought (according to the paper by Samanta et al.).

  24. 74
    Mark A. York says:

    Can someone put this guy’s accusations on climate sensitivity to rest? I used previous discussion on the Schwartz papers, but apparently that isn’t enough.

    “1) Annan and Hargraves 2006 found a climate sensitivity distribution of (1.7, 2.9, 4.9) not the 3C cited. Their paper came under criticism of how they handled the Bayes’ theorem at the center of their analysis (SV Henricksson Climate of the Past Discussions Sept 2009). Contrary to Dr Schwartz, there has been no response to the criticism.

    2) I guess you didn’t read step 6 of your realclimate citation. This is the heart of the Schwartz 2009 position: Realclimate uses the IPCC net forcing of 1.6 W/m2 for 2005 and a climate sensitivity of 0.75 C/ (W/m2) to calculate the expected equilibrium temperature increase of 1.2C vs. the observed 0.7C. They attribute the difference of 0.5 C to ocean warming (in the pipeline).This is a ocean warming of 0.7 W/m2.

    Ok, Schwartz’s points: a) With the IPCC GHG forcing of 2.63 W/m2 you need a negative aerosol forcing of -1.2 W/m2 to get 1.6 W/m2 (there are other minor forcings). With GHG 2.63 W/m2, the expected temp rise is an embarrassing 2.1C vs. the observed 0.7C. Aerosols have no agreed forcing history and the IPCC concedes the “level of scientific understanding” of aerosols forcing is “low”. So everything turns on aerosols not GHG

    b) Your required ocean warming of 0.7 w/m2 can’t be found. The IPCC lists it as 0.21 W/m2+/- 0.04 (see IPCC page 391). Schwartz uses 0.37 W/m2 in his 2009 paper. By my own analysis from 1955-2009, I get 0.26 W/m2. Kevin Trenberth Aug 2009, went looking for James Hansen’s claimed ocean heat uptake of 0.9 W/m2 and couldn’t find it.”

  25. 75

    Gilles (#56)–

    No doubt–presuming business as usual, at least. But with the other pressures (which actually DO drive deforestation in very troubling amounts–though Brazil has moved the trend in a better direction in recent years), will the “increased pressure” matter? If the warming due to AWG does in fact create a prolonged drought and a transition to savannah land, will the “increased pressure” matter?

    So with real pressures today, bringing in one that is currently (and over the next couple of decades) insignificant seems disingenuous at best. If we lose the Amazonian rainforest, it is highly unlikely that it will have anything to do with sugarcane growing.

  26. 76
    Deep Climate says:

    #60 Michael Tobis

    I agree entirely that the gap between the actual science and PR (or science journalism, for that matter) based upon it is problematic.

    It’s important, though, to distinguish between the case of McLean et al and the Amazon research of Samanta et al. In the case of McLean et al, the authors actively co-operated with a PR campaign that can only be characterized as disinformation. In fact, I would argue the whole point of that article’s publication was the ensuing dishonest PR campaign.

    In the current case, we have legitimate research that is being spun by the usual suspects. Unfortunately the lapse in PR (perhaps a misguided attempt to sensationalize the results) has made it easier for the spinmeisters.

    There was a similar case to do with research by Peter Clark at Oregon State University, where the PR mishandled the context, and was subsequently spun by Lawrence Solomon in the National Post (I don’t have the reference handy right now, but it’s a case I’ve been intending to look at).

    Coverage of Mojib Latif’s work by Fred Pearce in the New Scientist would fall in much the same category, I would say. A sincere but misguided interpretaion of the work was then distorted by Marc Morano and became a persistent contrarian talking point.

    To me, the current situation has two lessons:

    1) The PR needs to be carefully reviewed by the scientists to ensure its accuracy.

    and,

    2) Scientists need to speak out when their work or statements are distorted or misrepresented in the popular press.

    The following commentary by Terence Corcoran of the National Post is a prime example.

    http://network.nationalpost.com/NP/blogs/fullcomment/archive/2010/03/12/terence-corcoran-remember-amazongate.aspx

    Deltoid has discussion here:
    http://scienceblogs.com/deltoid/2010/03/its_always_bad_news_for_the_ip.php

    To be continued …

  27. 77
    Bob says:

    What doesn’t make sense to me is the quote by Ganguly, one of the paper’s authors (from the press release, or at least the version of it that I find everywhere on the Internet — emphasis mine):

    “This new study brings some clarity to our muddled understanding of how these forests, with their rich source of biodiversity, would fare in the future in the face of twin pressures from logging and changing climate,” said Boston University Prof. Ranga Myneni, senior author of the new study.

    The IPCC is under scrutiny for various data inaccuracies, including its claim — based on a flawed World Wildlife Fund study — that up to 40% of the Amazonian forests could react drastically and be replaced by savannas from even a slight reduction in rainfall.

    Our results certainly do not indicate such extreme sensitivity to reductions in rainfall,” said Sangram Ganguly, an author on the new study, from the Bay Area Environmental Research Institute affiliated with NASA Ames Research Center in California.

    [Again, emphasis mine.]

    What gives? Is Ganguly being quoted out of context (i.e is his quote being placed into a false context by the preceding two paragraphs)? In this context the quote strongly suggests that this study directly refutes the IPCC statement. It’s no surprise to me that people are getting confused.

  28. 78
    Andreas Bjurström says:

    Eric,
    My question was sincere. For people outside the “core group”, this Pielke vs. Romm, Climategate etc. debate seems overly emotional. What is left if we strip the emotions that are of interest for a limited number of people?

    For instance, I fail to see that you have a case for “Lubchenko”. I find the case overstated, yet reasonable. Why do you think otherwise? Moreover, stealth advocacy is one of Pielkes main concern as researcher. Some people here goes on and on about climate modelling :-)

    [Response: I don't doubt your sincerity. Many colleagues of mine that I know are sincere seem to think Pielke is "reasonable." All I can say is that well meaning people thought that Joe McCarthy was 'reasonable' too. Those people weren't paying attention (or they had rather un-American values). Now: read this post by Stefan (Sealevelgate in which he is unambiguously saying that IPCC is conservative (not alarmist), and then read RP Jr's post in which he misconstrues Stefan's post to mean that "another leading scientists says that IPCC is flawed." THERE is stealth advocacy for you. Look me in the eye and tell me you think Piekle is being "reasonable" here. (Note: I grant you that it is possible that Pielke may just be too stupid to have understood what Stefan wrote. But I doubt that.) --eric]

  29. 79
    Andreas Bjurström says:

    70 Nick Gotts,
    Please clarify your extravagant claims on a basis of ignorance :-)

  30. 80
    Hank Roberts says:

    Agreeing with Eli, those who wrote the press release ought to be following it up where it’s being misused.

    I asked way back –did the press release writers really mean to say, as they did, that the IPCC discussed changes in rainfall as brief as a calendar quarter? If so, why not a week, or a quarter of an hour? The IPCC talks about changes in climate, not weather.

    Yes, press officers ought to take responsibility to corral their scientists and ask the hard questions, when the scientists aren’t being clear or making sense. But once the gaffe — 8:02 PM — is being repeated around the bogusphere, both ought to be making an effort to correct it, beyond posting an unclear comment here.

  31. 81

    #296 Gilles
    Still interested in your response to my post #313 from the ‘Why We Bother’ thread?

    http://www.realclimate.org/index.php/archives/2010/03/why-we-bother/comment-page-7/#comment-166519


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  32. 82
    Andy says:

    Massive conversion of savannah to closed canopy forest has occurred in very little time throughout the SE United States where I work. In the western United States, minor climate changes are turning savannahs into non-forested landscapes.

    Savannahs are partially forested plant communities where recruitment into the canopy is restricted by sporadic survival of tree seedlings and saplings. While under natural conditions this sporadic recruitment is controlled by climate: for example in dry savannahs seedling survival is restricted by competition for water and nutrients with grasses and prolonged wet periods are needed for tree recruitment; or prolonged drought is needed to allow seedling survival where mortality is from drowning (bald cypress savannah).

    Thus removal of grass by cattle removes the tree’s main competitors and converts dry savannah into closed canopy forest under all weather conditions. Grazing also removes fuel for fires which further increases tree recruitment into the overstory. These factors along with outright fire supression and tree planting have converted savannah to forest all over the SE US where I work.

    The process has worked both ways in Africa where too many cows have converted savannahs into forests and brushlands by grass removal, and too many elephants have converted savannahs into grasslands by too much tree removal (elephants eat or otherwise destroy brush and trees).

    At any rate, changes in human behavior (lighting fires to clear agricultural lands in the Amazon) greatly exacerbate changes in forests and savannahs otherwise driven by climate. I think change is likely to come much more quickly than climate models or recent past experience alone predict.

  33. 83
    Reasonable Observer says:

    Hank Roberts says:
    “Oh, and for “reasonable observer” — you’re asking for a prediction in advance of the facts needed, while many links here could inform you of the work going on. We know this kind of flip happens — from the paleo record; at some level of decrease in rainfall/availability of groundwater, forests are replaced by grasslands. But that’s a gross oversimplification–it describes the change in the rock layers! The details, in living systems, are just now being looked at.”

    Remember the IPCC said:
    “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).”

    Dr. Lewis says he believes that statement is supported by the literature. I am just trying to get him (or anyone else) to give me a sense of what the literature actually says in his view.

    To me, there are three issues with the statement:
    1) “up to 40%”
    2) “could”
    3) “slight reduction”

    Does the literature suggest that 1% (up to 40) of the Amazon has a 10% change (could) of becoming savanna with a 25% (slight) reduction in rain? If so, I think we have a problem and the IPCC statement is technically true but obviously highly misleading and alarmist.

    Does the literature suggest that 30% (up to 40) of the Amazon has a 50% chance (could) of becoming savanna with a 5% (slight) reduction in rain? In that case, the IPCC statement is not just true but also an accurante reflection.

    I don’t know the answer so I asked Dr. Lewis to pitch in. If you don’t like my two sentences, then create one of your own that gives a more accureate reflection with better phrases than “up to”, “could” and “slight”.

    Hank seems to be saying that my request is unreasonable. But if you have no idea, then how do you know the original statement is an accurate reflection of the science?

    I am not saying I know the answer, I am just asking the experts to give us a better view.

    [Response: Here is a recent paper that is consistent with the IPCC statement: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2374898/
    This provides a way into lots of the literature. Also, see Lewis, S.L. (2006) Tropical forests and the changing earth system. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 361, 195-210. Available from this page: http://www.geog.leeds.ac.uk/people/slewis/publications.html
    --Simon]

  34. 84
    Eli Rabett says:

    Andreas, Eli had hoped to avoid Pielkeology, but for starts you might look at Jr.’s behavior in this case and this case and this case and oh yes, the time our boy went ballistic because Don Kennedy had not published something he submitted to Science, only to come back in a day or so to tell us that it had been submitted to Nature

  35. 85
    Bob says:

    Reasonable Observer,

    See this statement by Nepstad, a researcher on whose work at least some of the statement seems to have been based:

    Nepstad on IPCC Statement

    Also look for his referenced papers on the subject (not that hard to read, and by so doing you get to understand the methodology used, a bit about the ecosystem, and why one cannot set percentages for chances as you are requesting).

    I’ve found this one that doesn’t require a subscription:

    Amazon drought and its implications for forest flammability and tree growth: a basin-wide analysis

  36. 86
  37. 87
    CM says:

    Read in its context in the IPCC report, the slight-reduction-in-precipitation statement refers to a long-term reduction.

    However, two layers of poor referencing might mislead people into thinking the IPCC was saying a single drought could flip it. First, the IPCC’s reference to the Rowell and Moore 2000 report rather than to the first-hand studies. Second, R & M’s omission of relevant references for the first part of 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.

    Dan Nepstad has explained that R&M did have sources to back up the first sentence.

    Their omission made the observed fire vulnerability after the 1998 drought appear to be the basis for the 40% statement, though the numbers didn’t check out. Certainly had me confused.

    Which is why so much time is spent drumming into students the mechanics of source referencing. Pedantry aids understanding.

    Another thing students are taught is not to draw conclusions that go beyond what their data can support. That should apply to press releases as well.

  38. 88
    eric says:

    Note that Simon Lewis has replied to #42, #83 and to Samanta (#27).]

  39. 89
    Jim Steele says:

    “The evidence for the possibility of a major die-back of the Amazon rainforest is due to two factors,

    1. That climate change induced decreases in rainfall in the dry season occur, and..”

    I am confused. Warming models suggest warmer air increases moisture and therefore greater amounts of precipitation. So in the winter we expect more snow, but in the tropics less rain? The mechanisms for these generalized predictions seem a bit obscure.

  40. 90
    Ernst K says:

    72 Hank Roberts says:
    16 March 2010 at 12:00 PM
    [blockquote]Oh, and for “reasonable observer” — you’re asking for a prediction in advance of the facts needed, while many links here could inform you of the work going on. We know this kind of flip happens — from the paleo record; at some level of decrease in rainfall/availability of groundwater, forests are replaced by grasslands. But that’s a gross oversimplification–it describes the change in the rock layers! The details, in living systems, are just now being looked at.[/blockquote]

    We’re not restricted to the paleo-record. Since at least the 1990s there has been a lot of research into developing models that can predict the dominant vegetation type for a given climate. They have had success reproducing natural vegetation (see MAPSS, for example: http://www.fs.fed.us/pnw/mdr/mapss/index.shtml).

    Based on the way MAPSS models this, competition between forests and grassland is primarily dependent on the frequency of large scale fires. If fires are relatively infrequent, forests have a chance to re-establish themselves. If not, grasslands begin to take over because they can recover easily from such events.

    Because dry conditions encourage more fires, long term decreases in precipitation encourage more fires and encourage grasslands to potentially out-compete forests over the long term.

    Of course, there’s also competition between different species of a given vegetation class, which is a more difficult problem because there are so many different species with so many different responses to climate conditions.

  41. 91
    Gilles says:

    296:#296 Gilles
    Still interested in your response to my post #313 from the ‘Why We Bother’ thread?—

    Sorry I missed it. About my full name? I don’t think that it would be very interesting for you , but if you really want to, we can communicate by email.

  42. 92
    Eli Rabett says:

    OK, Eli has an Andreas question, why is the name Peter Cox missing in all this?

    [Response: Eli, with all due respect (and I do have a lot of respect for you), and at the risk of your calling me naive again, please don't stoppoing making this personal. If you have something to say about scientific work, say it. If you are merely going to use people's names -- e.g. Peter Cox -- with no context, then you are a) assuming the readers here know what you're talking about (I certainly don't) and b) risking casting unwarranted aspersions on people. The point of this post was "what the science shows is totally different than what is being said about it", NOT to speculate on the the underlying motivations of the authors or anyone else. Feel free to speculate about that on your own blog, but not here.--eric]

  43. 93
    CM says:

    Simon Lewis (inline at #27) very clearly addresses the misunderstanding of the IPCC paragraph on which the Samanta et al. press release seems to be based. The odd notion expressed in the press release, that the IPCC 40% statement was based on a ‘calculation’ in the WWF 2000 report, may stem from the confusion I noted at #87.

  44. 94
    CM says:

    Eli (#92), check out the Huntingford et al. paper Lewis cited above.

  45. 95
    Deep Climate says:

    #76

    Hmmm … I wrote that before I saw Samanta’s comment at #26 with Simon Lewis’s reply.

    It would appear that at least some of the co-authors do not understand that the press release’s discussion of the IPCC statement is misleading.

    It’s pretty clear that the press release overreaches, and that the denialosphere has torqued the findings even more. It’s disappointing that, so far at least, the authors are unwilling to acknowledge the obvious distortions of their work.

    In particular, Terence Corcoran claimed: “Some scientists have argued that the 2005 drought caused significant rainforest disturbances.” This appears to be an indirect reference to the Saleska et al 2007 paper. In other words, Corcoran (like Watts before him) actually presents a result that shows that there was in fact no positive response to the 2005 drought, as somehow anithetical to the IPCC. But the earlier result purported to show that a one-year drought could actually cause a positive response (due to increased sunlight), and this result is clearly now undercut (as Simon Lewis demonstrates so convincingly above).

    Since Corcoran claims that his interpretation is based on an interview with Myneni, the authors have no choice but to forthrightly disavow this particular interpretation of their work.

  46. 96

    #91 Gilles

    You can contact me through the OSS site:

    http://www.ossfoundation.us/contact-info

    We can communicate by email or phone. If you wish to remain anonymous that is your prerogative, but I for one appreciate more those who are willing to put their names behind their words on this issue. I do understand some have other issues re. anonymity, but when possible, it’s nice to see real names :)

    Would be happy to discuss by email, skype, or phone.

    John


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  47. 97
    Eli Rabett says:

    Eric, you have Eli very wrong. Peter Cox has done a lot of modeling of Amazon die back. Simply wondering why this has not been part of the discussion. For example:

    ———————
    Abstract: Simulations with the Hadley Centre general circulation model (HadCM3), including carbon cycle model and forced by a ‘business-as-usual’ emissions scenario, predict a rapid loss of Amazonian rainforest from the middle of this century onwards. The robustness of this projection to both uncertainty in physical climate drivers and the formulation of the land surface scheme is investigated. We analyse how the modelled vegetation cover in Amazonia responds to (i) uncertainty in the parameters specified in the atmosphere component of HadCM3 and their associated influence on predicted surface climate. We then enhance the land surface description and (ii) implement a multilayer canopy light interception model and compare with the simple ‘big-leaf’ approach used in the original simulations. Finally, (iii) we investigate the effect of changing the method of simulating vegetation dynamics from an area-based model (TRIFFID) to a more complex size- and age-structured approximation of an individual-based model (ecosystem demography). We find that the loss of Amazonian rainforest is robust across the climate uncertainty explored by perturbed physics simulations covering a wide range of global climate sensitivity. The introduction of the refined light interception models leads to an increase in simulated gross plant carbon uptake for the present day, but, with altered respiration, the net effect is a decrease in net primary productivity. However, this does not significantly affect the carbon loss from vegetation and soil as a consequence of future simulated depletion in soil moisture; the Amazon forest is still lost. The introduction of the more sophisticated dynamic vegetation model reduces but does not half the rate of forest dieback. The potential for human-induced climate change to trigger the loss of Amazon rainforest appears robust within the context of the uncertainties explored in this paper. Some further uncertainties should be explored, particularly with respect to the representation of rooting depth.
    ——————————

    and

    Why is the modeling missing??

    [Response: Eli, I'm not questioning your intentions. I'm just asking you to be clear. This time you are being clear. Thank you!--eric]

  48. 98
    Hank Roberts says:

    Aside: I have long felt a great fondness for Cox’s choice of acronym:

    > vegetation dynamics … model (TRIFFID)

    http://climate.uvic.ca/common/HCTN_24.pdf

  49. 99
    Patrick 027 says:

    89 Jim Steele -

    Precipitation is expected to increase in the global average with warming (but with some dependence on the cause of warming, because precipitation is limited by how much convective heat loss is required at the surface to balance net radiant heating; I think solar forcing has a greater effect than greenhouse warming in that regard, although warming tends to increase the fraction of convective heat loss from the surface that is evaporation; the same warming from more greenhouse forcing with an offset by cooling aerosols will result in less of an increase in precipitation because of the reduction of solar heating at the surface). The distribution may be restructured so that some areas recieve less precipitation (the forcing pattern may have spatial and temporal variation; but more importantly for forcings that are not too idiosyncratic, feedbacks are not evenly distributed, so that there are changes in temperature gradients, causing changes in winds, causing changes in heat fluxes and momentum fluxes and diabatic heating distributions, causing changes in temperature gradients and winds….) Also, evaporation rates tend to increase with higher temperature, so no change in precipitation can result in a loss of soil moisture. Seasonal and ~daily/hourly (or some such short time period) distributions of precipitation affect how ecosystems and economic infrastructure respond to it.

    78 Andreas Bjurström -

    What is left? The big picture is about what we thought it was, though we are looking at it through a foggy window, we can still make some confident conclusions.

    A picture with a mountain in it may also have a part without the mountain. That part doesn’t prove the mountain is not in the picture.

    – Gilles -

    1. A lot of people would not want biofuels to supply all or most of our energy. However, production possibilities curves are often convex; there may be a fraction of our energy that can be supplied by biofuels more easily than other sources without large costs to food and environment. Anyway: solar (PV, CSP, CPV, luminescent panels, skylights, water heaters), wind, hydroelectric (limited room for increase in average power, but can help in matching supply to load), geothermal, efficiency improvements, maybe nuclear …). Technology. Intelligence. Innovation. Policies to address externalities.

    2. Outside of mitigation, there is adaptation. Some optimal adaptation would be proactive. Proactive adaptation with efficiency requires prediction of changes. PLAN A: Suppose we use our best prediction and make investments and the climate change and ecosystem responses are different (either less or more, or different shapes) – then we’ve wasted resources. PLAN B: let’s assume the prediction is wrong and do something else. Question: What sign do we assume the error is? Question: How foolish do we feel when the prediction turns out to be right? PLAN C: Let’s do what we can to be prepared for all possibilities (in proportion to probability as best as can be judged). Well, similar problem as in PLAN A – the probability distribution might be off, but in addition, we have to invest more resources to cover the bases. PLAN D: Just be prepared for all possibilities equally. Well, that’s a bit wasteful, isn’t it, if only one possibility comes true or if only a few were likely.

    With maybe some caveats, if the sensitivity of any aspect of climate has a range of uncertainty, the the uncertainty in total effect should tend to be proportional to the forcing that is applied. So we can reduce uncertainty by reducing the forcing, and thus increase the efficiency of adaptation.

    (There is a natural level of uncertainty that makes reduction to zero impossible; nonetheless this natural level doesn’t saturate the range of possibilities and render other changes and, ***so for as I know**, uncertainties, moot. (if cost were linearly proportional to change, then it could be argued that, for the same time scale, any forced change less than the range of natural variability would have no net cost because it could reduce total change as easily as it increases total change; however, net costs would be incured by larger forced changes. The cost might not be linearly proportional; if the ecosystem and economy are adapated to a range of conditions, than any shift in that range risks increasing costs. Or even if the economy is not so flexible but the ecosystem is, … gets complicated, etc. And the forced changes could affect the range of natural variability (note I am not just refering to global average temperature; I’m refering to any ecologically or economically important climate variable, such as regional precipitation.). (Fortunately, some people actually have studied climate change costs/benifits)

    A simplistic argument to be sure; there could easily be some nonlinearities that I have not accounted for. Do *you* know what they are?

  50. 100
    Robert says:

    “But then saying ” but tree mortality increased, contributing temporarily to accelerating the rate of climate change” is disingenuous, since absolutely no significative “acceleration of the rate” is visible at all.”

    Speaking of disingenuous, your assertion is absurd. More CO2 accelerates climate change, because CO2 warms the earth. You do not have to demonstrate that each individual release of CO2 changes the global temperature trend in order to prove that. Next you’ll be asking scientists to prove the opening of a coal plant near your house changed to trend line. No. Your burden in challenging this idea can take one of two forms:

    * You can refute the century of atmospheric physics that tells us that more CO2 in the atmosphere causes warming, or;

    * You can explain why this CO2 increase (caused by decreased absorption and release from dead trees) is different from all the other CO2 increases.

    Or you can skip to your next denialist talking point. I won’t hold my breath.


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