DEFRA fund the Met Office to the tune of about £18M per year. I am on the Hadley Centre's Scientific Review Group and have reviewed the DEFRA proposal. Throughout the documents I get for the annual Review Group meetings and in the proposal, there is a constant thread of how the work they are doing is essential for IPCC. How this works though is that their scientists (just like us) write papers for the peer-review literature, and these get referred to in the IPCC Reports. DEFRA expects that their scientists will be involved in the IPCC Chapter writing. DEFRA has also funded the Met Office to run the Technical Support Unit of Working Group 2 of IPCC.
So, although IPCC work may not be a specific function of the Met Office, it is very much expected by DEFRA that they are heavily involved in IPCC. The Met Office and its Hadley Centre are happy to accept the kudos IPCC gets - especially the Nobel Peace Prize award in 2007 for IPCC itself. At least two people from the Met Office were at the award ceremony in Oslo - and only 25 in total were allowed to go.
If the Met Office can or are using this argument, then UEA could as well. Whether we should is another matter. Individual scientists at UEA are free to get involved in IPCC writing teams, and from the VC downwards (through the Dean of Science and the Head of School in ENV) would expect us to get involved. It is not written in any job description, but it is one of the unwritten expected things academics ought to do. Keith and I use the involvement when we write letters each to the ENV promotion committee to get a pay increment, as I expect all the others in ENV who have been involved in IPCC do. UEA also takes the kudos from the report coming out and many in ENV have nice certificates recording the Nobel Peace prize award last year. Involvement in IPCC and the Nobel Peace Prize features strongly in the ENV Annual Report. Like the Met Office we also use the IPCC involvement when writing proposals.
We're not paid to do IPCC, just like the Met Office scientists. We're paid expenses (by DEFRA) to go to the meetings and write the reports. Keith and I did much of this at weekends and evenings, but much also during work time and we used UEA resources to print out drafts. The work took time and we are paid by UEA, so UEA did subsidize us to do it.