Patrick Moore
Canadian ecologist (PhD, ecology, University of British Columbia). One of the early figures associated with Greenpeace in the 1970s; departed in the mid-1980s and subsequently became a public critic of the modern environmental movement. He has argued at various points that increased atmospheric CO₂ has measurable plant-growth benefits and that the case for rapid mitigation is overstated. He has held communications and policy roles for industries including aquaculture, mining and biotechnology, which is part of the publicly contested record on his work.
Tim Ball (1938-2022)
Canadian geographer (PhD, historical climatology, Queen Mary University of London). A longtime critic of the IPCC consensus position. Several of his publications were the subject of defamation suits brought against him (notably by Michael Mann and Andrew Weaver); the cases produced a mixed legal record, including one dismissal on procedural grounds. He published widely in op-ed and trade outlets rather than peer-reviewed climate journals.
Sen. James Inhofe (1934-2024)
U.S. senator from Oklahoma, 1994-2023. Chaired the Senate Environment and Public Works Committee. Long-running public position that anthropogenic warming is not policy-relevant; authored a 2012 book on the subject. He is included here as a policy voice rather than a scientist — his arguments are political rather than technical.
Michael Mann
American climatologist (PhD, geology and geophysics, Yale). Lead author of the "hockey stick" reconstruction (Mann, Bradley & Hughes, 1998-1999), one of the most-cited and most-litigated figures in mainstream climate science. Successive independent reviews (NAS 2006, Wahl & Ammann 2007) have affirmed the broad shape of the reconstruction while noting methodological caveats.
Judith Curry
American climatologist (PhD, geophysical sciences, University of Chicago). Former chair of the School of Earth and Atmospheric Sciences at Georgia Tech. Has published in peer-reviewed climate journals while also publicly arguing that the IPCC's confidence statements are overstated and that natural variability is under-weighted in some attribution work. Her position is sometimes called the "lukewarmer" view.
Note on selection
This list is illustrative, not exhaustive. We have included voices that show up frequently in the policy debate and that have a verifiable institutional record (PhD, faculty appointment, peer-reviewed publications, elected office). We have not graded the quality of their arguments — that is the reader's job, and the six-city data page exists in part to make that easier.