The IPCC has sometimes been compared to a church, and it some sense it may be true. Some prelates fly first class, but others just eke out a living in some developing country trying to save souls.
This is meant to be an illustration why a broad-brushed critique of the scientists collaborating with the IPCC can be quite off the mark. In some countries, IPCC lead authors and coordinating lead authors can apply for, or may receive, extra funds from to hire personel that assist them in their assignment to write, coordinate the writing of the report, and attend the IPCC meetings. However, other lead authors from less favoured European, i.e. theoretically developed, countries, do not receive any financial or other type of support. After being kindly asked by the corresponding national offices in charge of IPCC affairs to present your nomination as lead authors of the IPCC for the next Assessment Report (5), you are later kindly reminded that: the IPCC Buro will not cover any of your costs, that the national IPCC office will not cover any of your costs whatsoever; that should you wish to attend the IPCC Meetings in which the preparation of the report is discussed, you should be so kind and cover your travel expenses from your research budget or from the basic funding from your institutions. And, please, do not phone us again asking for travel support. You are already fully compensated with the honor of representing our wonderful country.
And so your life as an IPCC lead author of one of this wonderful countries - where a single football player can easily earn in a year an amount close to the whole IPCC budget- may look like this: travel to China, pay the costs by yourself, stay there exactly for the days of the IPCC meeting, travel back home and start writing the IPCC report, mostly in the weekends as the teaching load and regular research projects do not allow you to devote any time during weekdays. And Sunday night, read relevant blogs accusing you of leading a lavishly corrupt life.
Note: I am not an IPCC author