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The battle of Amazongate

Posted by Richard Wednesday, June 30, 2010

Before the Monbiot comments thread was shut down, with a "health warning" posted on his blog (pictured), we saw a guest appearance from Daniel Nepstad, who describes himself as: "the lead scientist on the research that underlies the IPCC statements about the sensitivity of the Amazon forest to reductions in rainfall."

In his view, the George Monbiot article and The Sunday Times decision was "an important victory for science and the public good," which is about as tendentious as you can get. Climate advocacy was the victor. Science, as so often, took the back seat.

That said, one might have thought that Nepstad was intervening in an attempt to resolve the core of the "Amazongate" dispute, as to whether the IPCC claim that 40 percent of the Amazonian rainforest could be wiped out with "even a slight reduction in precipitation" was unsubstantiated or not.

He starts with the assertion that "the evidence has only grown stronger in support of this statement" and tells us about the "enormous rainfall exclusion experiment in an Amazon forest" that he ran. And this was an extremely interesting experiment because it, rather than its designers, "identified the rainfall threshold beyond which giant forest trees die quite suddenly".

Notwithstanding that the work was not published in the journal Ecology until 2007 - after the date for inclusion in the IPCC report – we are told elsewhere that the purpose of the experiment was to "simulate the severe droughts the Amazon can experience during El Niño events."

The point about this intervention is that it does not come at the beginning of the debate, but well into a fractious and heated dispute where the issue has been quite narrowly defined in terms of whether the IPCC claim was "unsubstantiated". And, with the best will in the world, it is difficult to see how an experiment to simulate "severe droughts" can assist us.

Oblivious to this, however, Nepstad is intent on telling us about his work on drought thresholds, to which effect he cites the severe drought of 2005 and a paper (Philips et al. 2009 Science) published two years after the IPCC report. Once again, this is not helpful. In fact, it is distinctly unhelpful. On a scale of 1 to 10, where ten is "very helpful", it scores about minus nine zillion.

And it gets worse. The "lead scientist" then moves on to "two papers that seem to contradict our results, both using the same satellite sensor (MODIS)." But the reference is only invoked so that he can tell us that the papers are irrelevant to the IPCC statement and that "18 scientists including many of the world's authorities on tropical forest response to climate change," found the IPCC statement "to be sound".

All we can take away from this, then, is the view that the IPCC statement is "sound" because 18 "scientists" say so – the classic "appeal to authority". Helpfully though, Nepstad offers to explain the science behind the statement.

With that parked on the Monbiot site, the he re-appears in the comment section of Watts up with that? There, we are treated to "more information", based on "a few decades spent trying to figure out the Amazon forest's response to climate change and land use."

This is preceded by the rhetorical question: "Was there a peer-review citation in support of the IPCC statement on the Amazon at the time it was published?" And to that, the answer is:

Yes. In a 1994 paper in the journal "Nature" (Nepstad et al. 1994), we reported that approximately half of the forests of the Brazilian Amazon were exposed to severe seasonal droughts, and that these forest were able to endure these droughts through deep root systems that absorb moisture stored in deep soil layers. These results were refined in Nepstad et al in Global Change Biology (2004), where we found that, in 2001, half of the forests of the Amazon had depleted at least half of the moisture stored in the upper 10 meters of soil.
This is interesting for all sorts of reasons, some of which I address in my response. In citing Nepstad et al 1994, I say, he (Nepstad) knows full well that it does not support the IPCC. He knows that his 1994 paper refers to "severe seasonal droughts", whereas the IPCC claims an effect from a "slight reduction in precipitation".

So there we are, with – as I assert – the man spraying citations like a tomcat marking its territory. Yet we still haven't got to the bottom of this issue. In fact, we have an interesting paradox.

When Nepstad is called upon to identify peer-reviewed support for the IPCC, he goes for Nepstad et al 1994. There, he claims to have estimated "that approximately half of the forests of the Amazon depleted large portions of their available soil moisture during seasonal or episodic drought."

Perhaps unsurprisingly, when his partner organisation, the WWF, was called upon to identify the support for its report, the one used by the IPCC, it did not cite the 1994 paper but cited Nepstad et al 1999.

This is what the WWF calls Fire in the Amazon, "a 1999 overview of Amazon fire issues from the respected Instituto de Pesquisa Ambiental da Amazônia (IPAM – Amazon Environmental Research Institute)."

The source quotation, we are told, reads "Probably 30 to 40% of the forests of the Brazilian Amazon are sensitive to small reductions in the amount of rainfall." Intriguingly, the WWF then goes on to say: "Our report does NOT say that 40% of the Amazon forest is at risk from climate change."

This is where it gets really interesting. The English-language version of this document is listed on Woods Hole Research Center website. It is claimed to be one of the publications of the center, cited as:
Nepstad, D., A. Moreira, and A. Alencar. 1999. Flames in the Rainforest: Origins, Impacts and Alternatives to Amazon Fire. Pilot Program for the Conservation of the Rainforests of Brazil, World Bank. 140 pp.
The authors are identified as WHRC staff and, as is evident, the title is not Fire in the Amazon but Flames in the Rainforest.

As an IPAM publication, it reappears on the institute's website but in Portuguese only, cited as (translation in brackets underneath):
Floresta em Chamas: Origens, Impactos e Prevenção do Fogo na Amazônia

(Burning Forest: Origins, Impact and Prevention of Fire in the Amazon)

Este livro apresenta uma análise do fogo na Amazônia com a finalidade de identificar os meios pelos quais seus efeitos negativos podem ser reduzidos.

(This book presents an analysis of fire in the Amazon in order to identify the means by which negative effects can be reduced.)
The authors are cited as: ALENCAR, ANE; MOREIRA, ADRIANA; NEPSTAD, DANIEL. Brasília/DF. 1999.

Nowhere have we been able to find, online, a copy of the English version, but the IPAM version is available. A search of the 204-page document, though, does not yield the sentence: "Probably 30 to 40% of the forests of the Brazilian Amazon are sensitive to small reductions in the amount of rainfall," or anything like it - nothing even approximating it. The WWF may claim this document as its source, but there is no support for their claim in the Portuguese version (the only version bearing the IPAM imprimature).

However, in an IPAM/WHRC press release issued the previous year, which refers to the work on which the report is based, the claim is made that "unusually low amounts of rainfall in 1998 have increased the area of fire-vulnerable fire to more than one million square kilometers, or one third of the forests of Amazonia." The release was headed: "Flames in the Amazon forest". That is the closest we can get to a "30 to 40%" claim out of IPAM - and it refers to fire vulnerability, not die-back due to drought.

Nepstad himself never makes a reference to the 1999 IPAM report, even though he is the lead author. The closest he gets is in the WHRC press release issued in February of this year. Then, he talks about the IPAM website where, he claims, the statement that 30 to 40% of the forests of the Amazon were susceptible to small changes in rainfall was originally made (some time in the year 2000 or a little earlier). This is an unverifiable claim.

By contrast, in 2005, writing in an IPAM pamphlet headed: "Tropical Deforestation and Climate Change", Nepstad and others (including one of his co-authors from the 1999 pamphlet, Ane Alencar) declare:
Although the occurrence of logging or fire are perhaps the major determinants of human-induced forest biomass reduction, other variables influence the magnitude of these effects. The influence of logging on forest biomass and forest flammability, for example, depends on the intensity of the logging – the wood volume harvested per area and the type of damage reduction measures that were employed (Holdsworth and Uhl, 1997; Gerwing, 2002). Rainfall history and natural characteristics of the forest site as soil and vegetation type also influence the occurrence of fire on forests in the Amazon (Cochrane and Schulze, 1999; Cochrane et al., 1999; Barbosa and Fearnside, 1999; Haugaasen et al., 2003).

All these studies demonstrate that fire provokes significant reductions in the total biomass (alive and dead) of Amazon forests – from 15% to 40% of mature forest – and that this reduction is directly related to the intensity of logging, the intensity of drought, and the occurrence of previous fire between an unburned forest (undisturbed) and a logged and burned or just burned forest.
The suggestion by Nepstad in a 2005 IPAM document that up to 40% of mature forest is at risk, is uncanny. But, as previously, fire is the proximate cause.

Which is it to be? Nepstad can't have it both ways. The die-back is either due to a "slight reduction in precipitation" or to fire. His 40% figure points to the latter. As a result, I am willing to assert that, contrary to WWF claims, the 1999 IPAM document does not support the IPCC – a charge I make in the WUWT comments (notwithstanding also that it is not peer reviewed, plus all the other problems). And, responding directly to that assertion on the WUWT comments, Nepstad does not deny it.

Instead, he asserts: "North's comment reveals an important misinterpretation of the IPCC statement. He seems to be saying that IPCC is referring to droughts similar to those that have already taken place in the Amazon region. This is not true. The IPCC statement refers to reductions in precipitation BEYOND the historical pattern."

To that, I respond as follows (with slight corrections):
Nepstad's confident assertion that my comment reveals "an important misinterpretation of the IPCC statement" actually reveals more about what could charitably be called the IPCC's failure to communicate.

This has been compounded by the supporters of the IPCC, including Nepstad, who have been equally lacking in this department. They are in a poor position to lay down ex cathedra assertions on what might or might not be true, especially in offering a novel interpretation of the IPCC statement which cannot be adduced from any facts that it or its supporters have offered.

Nepstad might reflect, therefore, that it is the duty of those who seek to communicate information to make themselves clear – it is no part of ours to puzzle out what they mean to say, in the absence of any coherent elucidation.

In that context, if he wishes to assert an entirely new argument to the effect that that the "current" cycle of drought is one which has been super-imposed on the historical climate pattern, then he should be honest enough to declare that he is introducing a new argument, ex post facto, rather than complain that we have misinterpreted his previously opaque communications.

If then, Nepstad does wish to argue about variations in historical climate patterns, he might identify those patterns. For instance, we see Coe et al 2002 who tell us that there is considerable climatic variability in the Amazon basin", with "short (∼3–4 years) and long (∼28 years) modes of precipitation variability. Others write of different and longer cycles.

Thus, in order to accept Nepstad's assertion, we would need evidence (rather than speculation and the more typical ex cathedra pronouncements) that the drought cycle of 2005 and 2001 and 1998 and 1992 and 1983 differs significantly from climate patterns in the past. That information, so far, seems to have been notably lacking in his published work.

Further, while he refers to droughts in 1983 and 2001 (with a reference to the 1998 episode) he must also be aware of report of "major flooding" in Amazon basin the 1984-2001 period.

And, although as far as his published record goes, history seems to stop in 2005, he will undoubtedly be aware episodes of major flooding in the region for every year since 2005, recorded here and here and currently in the drier northeast.

Some might think that more honest commentators might temper their predictions of "severe drought" with at least a hat-tip to the reality, which at the moment is extremely soggy in parts.
But, confronted with a direct challenge to supply a reference to support the IPPC claim, the "lead scientist on the research that underlies the IPCC statements about the sensitivity of the Amazon forest to reductions in rainfall" fails to deliver. Instead, he moves the goalposts, accusing readers of misinterpreting the IPCC statement, imputing to it meaning that could hardly be inferred from the IPCC report.

In what he characterises as his closing comment, however, Nepstad then demonstrates contentment with his new line, heedless of the intellectual fragility of his position.

With no more evidence than he had to support the original assertion that 40 percent of the forest was at risk from a slight reduction in precipitation, the "lead scientist" has forged a new alibi. It is all a misunderstanding. The IPCC has not got it wrong, dear me no. We the readers have misinterpreted what it has said.

Understandably, Booker and I disagree.

Moonbat thread