Before the end of this period, a selection of about 50 scientists within each Working Group produces a first draft "Summary for policymakers" (SPM) summarizing its section of the full assessment report.
When the full assessment report is finalized, each second draft SPM is then reviewed during a four days plenary session comprising government delegations and observer organizations.
The objective of the review session is to improve the form of the SPM, which must remain faithful to the scientific content of the full assessment report.
Then each sentence of the draft SPM, displayed on a giant screen, was discussed at length by the delegates and often ended up completely rewritten.
When the discussion on a sentence lasted too long, a subgroup chaired by a scientist was formed to craft aside a revised text for later submission to the plenary.
We recognise IPCC as the world's most reliable source of information on climate change and its causes, and we endorse its method of achieving this consensus.
Agreement at such a meeting has ensured that the resulting document, so far as is possible, is scientifically accurate, balanced and free from personal or political bias.
[7]Martin Parry, co-chair of the IPCC Working Group II Fourth Assessment Report, has said:[8] The SPM is chewed over for some days (and sometimes nights) by the panel; and it is this process that has sometimes brought criticism from a few scientists who have questioned how much this government involvement alters the meaning of the scientists' conclusions.I do not think it does; Plenary might alter some nuances, but the key conclusions of the assessments remain intact.
[12] The report is prefaced by a policymakers' summary written by the editor, Sir John Houghton, director of the United Kingdom Meteorological Office.
His summary largely ignores the uncertainty in the report and attempts to present the expectation of substantial warming as firmly based science.