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Guest Speakers

and Presentations

HPAC regularly hosts presentations by their participants and other leading experts on a variety of global climate issues. Recordings, links to the presentation slides, and references, for these sessions are available below.

Guest Speaker Recordings, Slides & References

Conversations with Mark Jacobson: Solutions for Transitioning to Clean Renewable Energy, and Mike MacCracken and Herb Simmens: The Rationale for HPAC Support of Aggressive Mitigation.

Mark Jacobson is a Professor of Civil and Environmental Engineering at Stanford University. Mike MacCracken is a retired senior US climate research scientist and White House climate policy advisor, and Herb Simmens is an author of the 2023 book: A Climate Vocabulary for the Future. Both are also HPAC Steering Circle members.

Recording: Solutions for Transitioning to Clean Renewable Energy April 3, 2025.

Conversation with Bruce Parker about his "Scenario Explorer": a climate modeling simulator.

Recording: Scenario Explorer Mar. 20, 2025.

A conversation about The Belem Accord: A Global Pledge by Heads of State to Adopt a New Climate Goal and Plan to Restore a Safe and Healthy Climate for Humanity

Recording: Belem Accordown Feb. 20, 2025.

HPAC Townhall: reports from members on HPAC's 2024 activities and plans going forward.

Recording: HPAC Townhall Jan. 9, 2025.

HPAC Rountable: Rebightening.org, NOAC, Upper Limit Project, HCI, Operaatio Arktis

Remarks by leaders of each of the participating organizations followed by open discussion among the organizations and the HPAC membership:

Clive Ellsworth of Nature-based Ocean and Atmospheric Cooling (NOAC),

Alan Gadian of Rebrighten.org,

Rafe Pomerance of Upper Limit Project,

Soumitra Das of Healthy Climate Initiative,

Viktor Jaakola of Operaatio Arktis.

Recording: HPAC Roundtable Nov. 14, 2024.

Janos Pasztor, Ted Parson, and Ron Baiman, Former member of the Climate Overshoot Commission (COC) and Executive Director of the Carnegie Climate Governance Initiative (C2G), advisor to the COC and UCLA Professor of Environmental Law and HPAC Steering Circle member and (retired) Economics Prof, respectively.

Recording: Coordination and Governance of Direct Climate Cooling Oct. 2, 2024

Slides (Baiman presentation): Direct Climate Cooling Coordination and Governance

Anni Pokela and Viktor Jaakkola, Leaders of Operaatio Arktis, a Finnish youth-led climate action group.

Recording: Preserving Polar Ice Caps and Preventing Global Tipping Points Aug. 22, 2024

Website: https://www.operaatioarktis.fi/

Franz Oeste and Clive Elsworth, Engineers and entrepreneurs who have worked for many years on Iron Salt Aerosol and other direct climate cooling and methane removal efforts.

Recording: Cooling the Planet with Natural tropospheric Aerosol Processes (NTAP) Aug. 8, 2024

Slides: Cooling the Climate with Natural Tropospheric Aerosol Processes (NTAP)

Peter Fiekowsky, MIT-educated physicist and Silicon Valley entrepreneur and philanthropist with 27 patents and a long-term leader of the climate restoration movement.

Recording: The Climate Restoration Roadmap July 14, 2024

Book (with Carole Douglis): The Only Future That Will Sustain the Human Race (2022).

Walker Lee, Postdoctoral Research Associate at the National Center for Atmospheric Research

Recording: Marine Cloud Brightening Global Impact Modeling June 27, 2024

Slides: The Design Space of Marine Cloud Brightening

Oswald Petersen, CEO of Atmospheric Methane Removal AG

Recording: GeoRestoration with Methane Removal May 16, 2024

Herb Simmens, Author of A Climate Vocabulary for the Future

Recording: Meeting on Climate Vocabulary May 2, 2024

Rafe Pomerance

Recording: Setting a Sea Level Rise Limit,The Upper Limit Project April 4, 2024

Slides: The Upper Limit Project

Peter Ward, Professor of Biology, Professor of Earth and Space Sciences, University of Washington

Recording: Our Flooded Earth: Not if, but when March 7, 2024

Slides: Our Flooded Earth: Not if, but when

Dennis Garrity, Chair of the Board, Global EverGreening Alliance.

Recording: Direct Climate Cooling Advocacy Feb. 22, 2024

Slides: What's the Plan for Climate Cooling Advocacy

Dr. Katherine Romanak, Research Professor at the Bureau of Economic Geology, Jackson School of Geosciences, UT Austin.

Recording: Carbon Capture - Monitoring, Safety, and Geologic Impact of Underground CO2 Injection Feb. 8, 2024

Gideon Futerman, Researcher, interaction of SRM and Global Catastrophic Risk, Center for the Study of Existential Risk, Cambridge

Recording: What's the worst that could happen? Interaction of SRM and Global Catastrophic Risk Jan. 25, 2024

Companion Materials: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1753/

SRM Workshop Report

Viktor Jaakkola, Operaatio Arktis and Hugh Hunt, Deputy Director, Cambridge Centre for Climate Repair,

Recording: Experiences and Impressions of COP28 Jan. 11, 2024

Robert Tulip, Researcher and Author, Climate change, Jungian psychology, mythology, astronomy, and religion.

Recording: Religion's Ambiguous Relationship with Climate Change Dec. 14, 2023

Companion Paper: Religion's Ambiguous Relationship with Climate Change

Bruce Melton PE, Director, Climate Change Now Initiative; President, Melton Engineering Services, Austin.

Recording: A Photo Journal of Climate Impact Across America Nov 30, 2023

Michael MacCracken, Chief Scientist for Climate Change, The Climate Institute.

Recording: Communicating with Decisionmakers on Climate Change November 16, 2023

Doug MacMartin, Associate Professor, Mechanical and Aerospace Engineering, Cornell University

Recording: Sunlight Reflection Methods Nov. 2, 2023

Slides: Overview 2023

Alan Gadian, Visiting Scientist, National Center for Atmospheric Science and Research Scientist, University of Leeds

Recording: Is the planet really being cooked? What can be done about it quickly? Oct. 5, 2023

Chris Field, Co-chair of Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) Working Group 41 on ‘Ocean Interventions for Climate Change Mitigation

Recording: Conversation about the Overshoot Commission Report Sept 21, 2023

Podcast: HPAC takes over the Reviewer 2 (R2) podcast!

Chris Vivien, Co-Chair WG41 Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP)

Recording: Governance of Ocean Intervention for Climate Intervention Aug. 24, 2023

Slides: The London Protocal and Marine Geoengineering

Why it is Not a Good Idea to Fertilise Ocean Gyres?

Phoebe Barnard, Founding CEO/Exec Director of the Stable Planet Alliance

Recording: The Global Restoration Alliance July 13, 2023

Oliver Morton, Editor, The Economist; Author, The Planet Remade: How Geoegnineering Could Change the World

Recording: Conversation with Oliver Morton June 29, 2023

Graeme Taylor, Co-author (with Sue Vink) of Managing the risks of missing international climate targets May 4, 2023.

Recording: The Scientific Fallacies Preventing Effective Climate Mitigation

Link to Managing the risks of missing international climate targets.

David Spratt, Research Director at Breakthrough National Center for Climate Restoration

Recording: Conversation with David Spratt April 20th, 2023

David Keith, Professor of Applied Physics and Public Policy at Harvard, Founder of Carbon Engineering

Recording: Conversation with Dr. David Keith April 4, 2023

Zeke Hausfather, Climate Research Lead at Stripe, The Breakthrough Institute Senior Fellow

Recording: Conversation with Zeke Hausfather March 23 2023

Robert Chris, Researcher and Author, Systemic Factors influencing global climate policy; PhD, Philosophy

Robert Tulip, Researcher and Author, Climate change solutions; Australian Agency for International Development, 1989-2017;
Master’s Degree, Ethics and Ontology

Recording: Two Roberts Wrestle with Moral Hazards March 9, 2023

Dr. Martha Schwartz, Research Professor, Harvard Graduate School of Design,

Recording: The Urban Landscape and The Future of Cities February 26, 2023

Slides: Climate Change and the Urban Environment

Luke Iseman, Co-Founder, Make Sunsets

Recording: Make Sunsets Overview February 9, 2023

Brad Ack, Chief Executive Officer, Ocean Visions

Recording: Advancing Solutions for Ocean-Climate Restoration January 3, 2023

Dr. Shaun Fitzgerald OBE FREng, Director Centre for Climate Repair(CCRC), Cambridge

Recording: CCRC Climate Solutions Research Update December 15, 2022

Slides: The Three "R's" of Climate Repair

Conversation with Biochar Expert Panel: Shannon Lee, John Frank, Tony Miller, Brian von Herzen, Matt Lucas, Andrew North and Matt Beres.