This table appears in chapter nca4-front-matter of the Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II report.

This table describes the meaning of various categories of confidence level and likelihood assessment used in NCA4. The levels of confidence are the same as they appear in the CSSR (NCA4 Volume I). And while the likelihood scale is consistent with the CSSR, there are fewer categories, as that report relies more heavily on quantitative methods and statistics. This “binning” of likelihood is consistent with other USGCRP sustained assessment products, such as the Climate and Health Assessment4 and NCA3.372aedbf-1493-48d9-8703-5bec046576fe

This table is composed of these arrays :

7e1a71c6 (2x5)

Very Likely	Likely	As Likely as Not	Unlikely	Very Unlikely
≥ 9 in 10	≥ 2 in 3	= 1 in 2	≤ 1 in 3	≤ 1 in 10

95c25f32 (2x4)

Very High	High	Medium	Low
Strong evidence (established theory, multiple sources, consistent results, well documented and accepted methods, etc), high consensus	Moderate evidence (several sources, some consistency, methods vary and/or documentation limited, etc.), medium consensus	Suggestive evidence (a few sources, limited consistency, models incomplete, methods emerging etc.), competing schools of thoughs	Inconclusive evidence (limited sources, extrapolations, inconsistent findings, poor documentation and/or methods not tested, etc), disagreement or lack of opinions among experts