Confidence and likelihood
Sometimes it is difficult to understand exactly what phrases like very likely and high confidence actually mean.
The IPCC process gives these phrases express meanings. These meanings and explanations are shown below and are taken from the article in The Conversation by Roger Jones, Explainer: How to read an IPCC report.
|Likelihood terminology||Likelihood of the outcome|
|Virtually certain||>99% probability|
|Extremely likely||>95% probability|
|Very likely||>90% probability|
|More likely than not||>50%probability|
|About as likely as not||33-66% probability|
|Very unlikely||<10% probability|
|Extremely unlikely||<5% probability|
|Exceptionally unlikely||<1% probability|
By contrast, confidence is expressed qualitatively, which is expressed as levels of agreement and evidence.
You can get a clear idea of this in the figure below.