A research paper doesn’t talk about increased crop damage by insects. But as occurred in the Himalayan glacier incident, the erroneous claim remains in the about-to-be released report.

In a few weeks, the Intergovernmental Panel on Climate Change (IPCC) will release its Working Group 2 report. Chapter 7 is called Food Security and Food Production Systems. A leaked copy can be downloaded here.

Click to enlarge. Text appears near bottom of p. 23 of the leaked, final draft of Chapter 7

On page 23, we ‘re told that:

there is a tendency for risk of insect damage to plants to increase [as temperatures rise].

Two pieces of evidence are cited for this statement. One, a paper authored by Matthew Paulson plus three co-authors, was published in 2009. It’s available online and appears to backup the IPCC’s claim. Kind of.

Its conclusions involve no real-world data. Instead, this paper is about speculative, theoretical prediction. The phrase “we speculate” appears in the abstract. The authors say their mathematical model implies that certain conditions will become more likely. Which “could have profound implications for pest management during future climatic warming.” Not exactly persuasive evidence that the damage insects do to crops will increase significantly.

The other study cited by the IPCC is even more problematic. Written by Curtis Deutsch and six others, it was published in 2008. The full text is also online. The authors say they’ve combined “empirical fitness curves” with “projected geographical distribution of climate change for the next century” and have concluded that insects living in the tropics may suffer more from global warming than insects that live in cooler locales.

Are crops discussed? No. Plants generally? Nope. Damage inflicted by insects? Not a word about any of these matters appears in that study. It does not, therefore, backup the IPCC’s claim that “insect damage to plants” will increase along with temperature.

What’s remarkable is that a representative of the government of The Netherlands pointed this out to the IPCC last year. Comment #494 may be seen at the bottom of page 42 of this collection of comments submitted during the second round of external review that took place between March and May 2013.

Comment #494 was then highlighted by one of Chapter 7’s Review Editors, Kaija Hakala, who quoted it verbatim a few months later:

“The Deutsch 2008 paper does not consider the effect of climate change on insect damage to plants, and is thus inappropriate as a reference to this statement.” [bold added by Hakala; see p. 2 here]

But the IPCC Chapter 7 authors chose to ignore these warnings. So the erroneous citation remains in the Final Draft of their contribution to the Working Group 2 report.

If you’re experiencing déjà vu, welcome to the club. Back in 2007, Working Group 2 was responsible for the embarrassing Himalayan glacier error. A 2010 report concluded that this debacle could have been avoided entirely had the IPCC merely listened to its own reviewers.

Then, just as now, the mistake was noticed. Then, just as now, “the authors did not change the text.”

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