Posted on 08/07/2007 7:59:18 AM PDT by IrishMike
For what the IPCC really says, go here:
"The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence7 that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative forcing of +1.6 [+0.6 to +2.4] W m-2. (see Figure SPM-2). {2.3. 6.5, 2.9}"
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations12. This is an advance since the TAR’s conclusion that “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations”. Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns (see Figure SPM-4 and Table SPM-2). {9.4, 9.5}"
Footnote 6 reads: "In this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood, using expert judgement, of an outcome or a result: Virtually certain > 99% probability of occurrence, Extremely likely > 95%, Very likely > 90%, Likely > 66%, More likely than not > 50%, Unlikely < 33%, Very unlikely < 10%, Extremely unlikely < 5%. (See Box TS.1.1 for more details)."
Footnote 7 reads: "In this Summary for Policymakers the following levels of confidence have been used to express expert judgments on the correctness of the underlying science: very high confidence at least a 9 out of 10 chance of being correct; high confidence about an 8 out of 10 chance of being correct. (See Box TS.1.1)"
Footnote 12 reads: "Consideration of remaining uncertainty is based on current methodologies."
Note that they do not quantify the usage of "most" in the second quote, at least in the Summary for Policymakers. The full report might.
I would skip the summaries. The IPCC reports are generally pretty good...but the summaries are where the politics come in. They must spend a lot of hours on those things.
Section 9.4.1.2 may be of interest to you.
You expressed uncertainty and I attempted to remedy that. The Summary provides information regarding about the uncertainty you expressed.
Right. I was not exactly referring to what you said, just to the policy summary in general. Sorry if that came across wrong.
Wrong. You didn’t read the terms and conditions. See the italics in #4.
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