Uploaded June 2026 | Updated September 2026, 3 weeks ago
For more than 15 years, the RCP8.5 climate scenario has shaped headlines, policy decisions, financial stress tests and public understanding of climate risk. Now, the scientific community has declared it implausible. So what comes next?
This week on Cleaning Up, Michael Liebreich welcomes Professor Roger Pielke Jr. back to explore why RCP 8.5 became the dominant "business as usual" climate scenario, and what its demise means for climate research, policymaking and public debate.
They discuss the origins of the scenario, how assumptions about coal consumption drove projections beyond plausible futures and ask whether fear-based climate communication has ultimately helped or hindered public support for climate action. They tackle tipping points, extreme weather, climate policy, scientific self-correction, and the crucial question of how societies should respond to climate risk in a world that is still warming.
Until recently, Roger was a tenured professor at the University of Colorado at Boulder. He is now senior fellow at the American Enterprise Institute and publishes an influential Substack called The Honest Broker. He last made an appearance on Cleaning Up in June 2022. If you want to know the background to the RCP8.5 controversy you should listen to that episode, linked below.
Leadership Circle:
Cleaning Up is proud to be supported by its Leadership Circle. The members are Actis, Alcazar Energy, Arup, Copenhagen Infrastructure Partners, Cygnum Capital, Davidson Kempner, Ecopragma Capital, EDP, Eurelectric, the Gilardini Foundation, KKR, Mitsubishi Heavy Industries, National Grid, Octopus Energy, Quadrature Climate Foundation, Schneider Electric, SDCL and Wärtsilä. For more information about the Leadership Circle, visit cleaningup.live
Links:
• Van Vuuren’s 2026 paper on RCP8.5 becoming implausible: gmd.copernicus.org/articles/19/2627/2026
• Van Vuuren’s 2011 paper on the development of the Representative Concentration Pathways (RCPs): link.springer.com/article/10.1007/s10584-011-0148-z
• The Honest Broker Substack: rogerpielkejr.substack.com
• Michael's writeup on RCP8.5: mliebreich.substack.com/p/rcp-85-is-officially-bollox
• Roger Pielke Jr’s past appearance on Cleaning Up: youtube.com/watch?v=K2LpMpkrP1w
• Johan Rockström on Cleaning Up: youtu.be/eIJkt_mY12s
• Jim Skea on Cleaning Up: youtu.be/oAWUdL5ZKsk
Chapters:
00:00 - Coming Up
00:55 - Intro
05:00 - The Honest Broker
08:00 - US Climate Policy
10:30 - Chris Wright’s Review
14:00 - Renewables Overtake Coal
15:37 - RCP8.5 is Dead
19:00 - Why Does It Matter?
22:00 - Plausability
25:00 - Trends in Coal
31:00 - What Do Policymakers Do?
35:30 - Alternative Scenarios
40:00 - The New High Scenario
45:30 - Tipping Points
50:00 - Aggressive Mitigation
54:00 - Self Correction
57:00 - Hurricane Damage
01:01:47 - Outro
For more than 15 years, the RCP8.5 climate scenario has shaped headlines, policy decisions, financial stress tests and public understanding of climate risk. Now, the scientific community has declared it implausible. So what comes next?
This week on Cleaning Up, Michael Liebreich welcomes Professor Roger Pielke Jr. back to explore why RCP 8.5 became the dominant "business as usual" climate scenario, and what its demise means for climate research, policymaking and public debate.
They discuss the origins of the scenario, how assumptions about coal consumption drove projections beyond plausible futures and ask whether fear-based climate communication has ultimately helped or hindered public support for climate action. They tackle tipping points, extreme weather, climate policy, scientific self-correction, and the crucial question of how societies should respond to climate risk in a world that is still warming.
Until recently, Roger was a tenured professor at the University of Colorado at Boulder. He is now senior fellow at the American Enterprise Institute and publishes an influential Substack called The Honest Broker. He last made an appearance on Cleaning Up in June 2022. If you want to know the background to the RCP8.5 controversy you should listen to that episode, linked below.
Leadership Circle:
Cleaning Up is proud to be supported by its Leadership Circle. The members are Actis, Alcazar Energy, Arup, Copenhagen Infrastructure Partners, Cygnum Capital, Davidson Kempner, Ecopragma Capital, EDP, Eurelectric, the Gilardini Foundation, KKR, Mitsubishi Heavy Industries, National Grid, Octopus Energy, Quadrature Climate Foundation, Schneider Electric, SDCL and Wärtsilä. For more information about the Leadership Circle, visit cleaningup.live
Links:
• Van Vuuren’s 2026 paper on RCP8.5 becoming implausible: gmd.copernicus.org/articles/19/2627/2026
• Van Vuuren’s 2011 paper on the development of the Representative Concentration Pathways (RCPs): link.springer.com/article/10.1007/s10584-011-0148-z
• The Honest Broker Substack: rogerpielkejr.substack.com
• Michael's writeup on RCP8.5: mliebreich.substack.com/p/rcp-85-is-officially-bollox
• Roger Pielke Jr’s past appearance on Cleaning Up: youtube.com/watch?v=K2LpMpkrP1w
• Johan Rockström on Cleaning Up: youtu.be/eIJkt_mY12s
• Jim Skea on Cleaning Up: youtu.be/oAWUdL5ZKsk
Chapters:
00:00 - Coming Up
00:55 - Intro
05:00 - The Honest Broker
08:00 - US Climate Policy
10:30 - Chris Wright’s Review
14:00 - Renewables Overtake Coal
15:37 - RCP8.5 is Dead
19:00 - Why Does It Matter?
22:00 - Plausability
25:00 - Trends in Coal
31:00 - What Do Policymakers Do?
35:30 - Alternative Scenarios
40:00 - The New High Scenario
45:30 - Tipping Points
50:00 - Aggressive Mitigation
54:00 - Self Correction
57:00 - Hurricane Damage
01:01:47 - Outro
