Presumed Parameters - Climate Change: Identification and Projections - page 55

5

Presumed Parameters

The aim of this chapter is to draw out, through the major IPCC
documents, in particular AR5 and SPM, the climatic parameters' values as
well as their ranges of uncertainty, with a view to comparing them to the
results of identification.

5.1. Terminology

In the IPCC documents, certain qualifying terms are systematically given
in italics: likely, very likely , or even: high confidence, low confidence , and so
on. They refer to a precise and restrictive scale (Mastrandrea et al ., 2010).
They may apply to the quantified value of a variable, or to any kind of
assertion.

Regarding a variable, quantified by an equality or inequalities, the
probabilities are expressed using the following scale:

Virtually certain 99-100 %

Extremely likely 95-100 %

Very likely 90-100 %

Likely 66-100 %

More or less equally likely 33-66 %

Unlikely 0-33 %

Very unlikely 0-10 %

Extremely unlikely 0-5 %

Exceptionally unlikely 0-1 %