We compiled a database of 1,372 climate researchers and classified each researcher into two categories: convinced by the evidence (CE) for anthropogenic climate change (ACC) or unconvinced by the evidence (UE) for ACC.
We defined
CE researchers as those who signed statements broadly agreeing
with or directly endorsing the primary tenets of the IPCC Fourth Assessment Report that it is “very likely” that anthropogenic greenhouse gases have been responsible for “most” of the “unequivocal” warming of the Earth’s average global temperature in the second half of the 20th century (3). We compiled these CE researchers comprehensively from the lists of IPCC AR4 Working Group I Contributors and four prominent scientific statements endorsing the IPCC (n = 903; SI Materials and Methods).
We defined UE researchers as those who have signed statements strongly dissenting from the views of the IPCC.We compiled UE names comprehensively from 12 of the most prominent statements criticizing the IPCC conclusions (n = 472; SI Materials and Methods).
Only three researchers were members of both the CE and UE groups (due to
their presence on both CE and UE lists) and remained in the dataset, except in
calculations of the top 50, 100, and 200 researchers’ group membership.