In the fourth episode of In Defense of Climate Change, Bryce Nickels and climate policy scholar Roger Pielke Jr. discuss one of the most consequential developments in climate science in years: the retirement of the extreme climate scenario known as RCP 8.5.
The conversation covers why many of the “worst-case” climate projections were based on implausible assumptions about future coal use and why recent updates to climate scenario frameworks represent a major course correction. The discussion also explores the difference between exploratory scientific scenarios and policy roadmaps, the relationship between climate science and political decision-making, and how climate narratives influence public policy around the world.
Bryce and Roger also discuss parallels between climate science governance and debates surrounding gain-of-function research, including questions about transparency, accountability, expert authority, and the role of broader public input in scientific decision-making.
(recorded May 22, 2026)
Timestamps
00:30 – Introduction
02:48 – What RCP 8.5 is and why it mattered
06:10 – Retirement of the extreme climate scenarios
07:23 – How climate scenario committees operate
10:12 – History of international climate coordination
14:16 – Accountability and representation concerns
18:00 – Climate scenarios and global development policy
20:45 – Science, politics, and policymaking
25:46 – Comparisons to gain-of-function debates
28:08 – “Business as usual” climate narratives
34:24 – Outdated assumptions in climate policy
35:25 – Incentives for reforming climate modeling
37:28 – The U.S. role in the IPCC
40:38 – Public backlash and the social cost of carbon
45:28 – Climate concern vs. climate policy costs
49:08 – Energy abundance and pragmatic decarbonization
51:36 – Roger reflects on criticism and vindication
54:56 – Scientific self-correction and closing thoughts
intro and outro by Tess Parks
About the Series
In Defense of Climate Change features conversations between climate policy scholar Roger Pielke Jr. and Rutgers professor and Science From the Fringe host Bryce Nickels. The series examines one of the most politically polarized areas of modern science—what the evidence actually shows about climate change, and how those findings are interpreted, amplified, and sometimes distorted once they enter politics and the media. By focusing on data, historical context, and intellectual honesty, the conversations aim to cut through extreme narratives and separate the underlying science from the stories that often dominate public debate.
About Roger Pielke Jr.
Roger Pielke Jr. is a Senior Fellow at the American Enterprise Institute and professor emeritus at the University of Colorado Boulder, where he served on the faculty from 2001 to 2024 and founded the Center for Science and Technology Policy Research. His work focuses on the intersection of science, policy, and politics, particularly in climate, energy, innovation, and sports governance. In 2024 he was elected to the Norwegian Academy of Science and Letters and also holds an honorary professorship at University College London. He writes the widely read Substack The Honest Broker, which has more than 37,000 subscribers worldwide, and is the author of several books on science policy, including The Honest Broker and The Climate Fix.
