I have been in the field of science for some time now and I have not been aware of the term "very likely" translating to "more than 90% certainty."
I have been in the field of science for some time now and I have not been aware of the term "very likely" translating to "more than 90% certainty.
You obviously have not been associated with the right scientists. I bet you have never even spoken to Prof. Albert Gore, have you? See.
I am not in the field of science but had the same observation. 90% certain is an oxymoron.
I have been in the field of science for some time now and I have not been aware of the term "very likely" translating to "more than 90% certainty."
It probably came from IPCC "Summary for Policymakers" footnotes, as it does for the Third Assessment Report.
specifically: http://www.grida.no/climate/ipcc_tar/wg1/fnspm.htm#7
"In this Summary for Policymakers and in the Technical Summary, the following words have been used where appropriate to indicate judgmental estimates of confidence: virtually certain (greater than 99% chance that a result is true); very likely (90-99% chance); likely (66-90% chance); medium likelihood (33-66% chance); unlikely (10-33% chance); very unlikely (1-10% chance); exceptionally unlikely (less than 1% chance). The reader is referred to individual chapters for more details."
UN/IPCC defines terms to suit their purposes. It definitely pays to check their footnotes and glossary of terms they put into their documents, their use of language is very deliberate and often leaves traps for the unwary, especially when they make statements as to uncertainty of an prognostication. Of course such usage just begs the question of how do they go about assessing the uncertainty to assign such phraseology.
In light of the very high probability that such assessements are essentially bayesian in character and assigning express percentages to such terms is very reminecent of what would come of applying the concepts expressed in this paper authored by Steven Schneider, (one of the historical heavy lifters in the anthropogenic global warming crew), I would say so:
http://stephenschneider.stanford.edu/Publications/PDF_Papers/UncertaintiesGuidanceFinal2.pdf
"A final note before turning to the specific recommendations themselves-the paper assumes that for most instances in the TAR, a "Bayesian" or "subjective" characterization of probability will be the most appropriate (see, e.g., Edwards, 1992, for a philosophical basis for Baysian methods; for applications of Bayesian methods, see e.g., Anderson, 1998; Howard et al., 1972). The Bayesian paradigm is a formal and rigorous language to communicate uncertainty. In it, a "prior" belief about a probability distribution (typically based on existing evidence) can be updated by new evidence, which causes a revision of the prior, producing a so-called "posterior" probability. Applying the paradigm in the assessment process involves combining individual authors' (and reviewers') Bayesian assessments of probability distributions and would lead to the following interpretation of probability statements: the probability of an event is the degree of belief that exists among lead authors and reviewers that the event will occur, given the observations, modeling results, and theory currently available. When complex systems are the topic, both prior and updated probability distributions usually contain a high degree of (informed) subjectivity. Thus in the TAR, we expect Bayesian approaches to be what is most often meant when probabilities are attached to outcomes with an inherent component of subjectivity or to an assessment of the state of the science from which confidence characterisations are offered."
And the intent of the use of such terms:
"It is certainly true that "science" itself strives for objective empirical information to test theory and models. But at the same time "science for policy" must be recognized as a different enterprise than "science" itself, since science for policy (e.g., Ravetz, 1986) involves being responsive to policymakers' needs for expert judgment at a particular time, given the information currently available, even if those judgments involve a considerable degree of subjectivity. "
P.S.
Mix polling & concensus politics with a the cloak of "science" one should not be surprised at what comes out of it. Add the knowledge that this is driven by general assembly UN politics at its core, the result is a foregone conclusion before the first draft report is it is even begun.