[Not by anyone familiar with the IPCC citation policies, and certainly not in WG2 or WG3. Whether or not you and I agree with citing grey literature, it's not against the IPCC's policies. -Kate]

Let’s take Africagate for instance. Its been repeated many times that in Africa by 2020, “in some countries, yields from rain-fed agriculture would be reduced by 50%”.

http://news.bbc.co.uk/1/hi/in_depth/629/629/6528979.stm
http://www.dfid.gov.uk/Media-Room/Case-Studies/2009/Adaptation-is-key-to-tackling-climate-change-/
http://www.ipcc.ch/pdf/presentations/valencia-2007-11/pachauri-17-november-2007.pdf
http://www.raeng.org.uk/events/pdf/Dr_Pachauri's_International_slides.pdf
http://www.reuters.com/article/idUSL22658148
http://emagazine.credit-suisse.com/app/article/index.cfm?fuseaction=OpenArticle&aoid=275229&video=true&void=275237&lang=EN

All of this comes from IPCC’s citing of Agoumi (2003):

http://www.cckn.net/pdf/north_africa.pdf

The most support Agoumi appears to have for this statement is from a Moroccan government report:

http://unfccc.int/resource/docs/natc/mornc1e.pdf

It states that it expects by 2020, “a decrease in cereal yields by 50% in dry years and 10% in normal years.”

This is hardly the same thing.

[Have you been able to get a hold of the UNEP-GEF Project RAB94G31? That's the other citation Agoumi gives for the list that claim was part of, but it doesn't seem to be available online. -Kate]

It seems that Jonathan Leake does have something to stand on here considering he has Robert Watson, chairman of the IPCC from 1997 to 2002, stating “Any such projection should be based on peer-reviewed literature from computer modelling of how agricultural yields would respond to climate change. I can see no such data supporting the IPCC report,”

http://www.timesonline.co.uk/tol/news/environment/article7017907.ece

There is a legitimate point here (which is also held by Professor Chris Field, the new lead author of the IPCC’s climate impacts team).

I think the IPCC will be much more careful this time around in its citing of grey literature, and this can only be a good thing.

James Delingpole, Christopher Booker and David Rose are the most guilty

[Don't forget Jonathan Leake. -Kate]