Cleaning Up: Leadership in an Age of Climate Change

The US Just Sank Shipping's Big Plan for Decarbonization, What Now? | Ep229: Tristan Smith

Oct 22, 2025

In this insightful discussion, Professor Tristan Smith from UCL Energy Institute, an expert in shipping decarbonisation, dives into the recent turmoil at the International Maritime Organisation. Shipping, which accounts for around 3% of global emissions, faced a significant setback as the US delayed a crucial vote on carbon intensity regulations. Tristan explains the implications of this intervention, the complexities of maritime policy, and the risks of relying on fossil fuels. He also evaluates emerging alternatives like nuclear and e-fuels amidst the challenges they present for the industry.

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INSIGHT

Shipping's Significant Climate Footprint

Global shipping emits about 1 GtCO2e annually, roughly 2–3% of global emissions and similar to Japan or Germany.
Shipping is essential to world trade and remains tightly coupled to burning oil for propulsion.

ANECDOTE

Fifteen Years Inside IMO Negotiations

Tristan Smith has attended IMO MEPC meetings for 15 years and watched climate policy evolve there.
He originally went to learn rule-making after moving from naval defence work into shipping decarbonisation.

INSIGHT

Flag Registries Shape IMO Power

The IMO's MARPOL rules can enter into force only when enough flag states ratify them, giving flag registries outsized influence.
Major flags like Panama, Marshall Islands and Liberia shape global compliance dynamics.

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Global shipping contributes about 3% of global greenhouse gas emissions, equivalent to the total emissions of Japan or Germany. The sector, including its contribution to climate change, is governed by the International Maritime Organisation or the IMO, which is a UN agency based in London in the United Kingdom.

Last week, the International Maritime Organisation gathered to vote on a proposal to reduce emissions from ships that had been agreed to in principle earlier this year. And ahead of the gathering, most people intimately involved in the process thought the proposal would pass. But that wasn’t the case. The US stepped in at the last minute and pressured all those gathered to delay the vote on the proposal for another 12 months.

This week on Cleaning Up, host Bryony Worthington sits down with Professor Tristan Smith, a leading expert on shipping decarbonisation from UCL Energy Institute, to unpack the dramatic events at the latest International Maritime Organization meeting — where the United States’ last-minute intervention derailed a landmark vote on cutting emissions from ships.

Together, they explore:

How global shipping, responsible for around 3% of greenhouse gas emissions, became a critical test case for international climate policy
Why the IMO’s proposed carbon intensity regulation could have marked the beginning of the end for oil and LNG as marine fuels
The “Tariff diplomacy” and other threats that reshaped global negotiations
What this means for COP30 and other multilateral agreements.

Bryony and Tristan also dive deep into possible solutions: from e-fuels, ammonia, and battery electrification to nuclear propulsion — weighing what’s practical, what’s political, and what’s merely wishful thinking.

Leadership Circle:

Cleaning Up is supported by the Leadership Circle, and its founding members: Actis, Alcazar Energy, Davidson Kempner, EcoPragma Capital, EDP of Portugal, Eurelectric, the Gilardini Foundation, KKR, National Grid, Octopus Energy, Quadrature Climate Foundation, SDCL and Wärtsilä. For more information on the Leadership Circle, please visit https://www.cleaningup.live.

Links and more:

Is Shipping the Easiest "Hard-to-Abate" Sector? - Ep143: Johannah Christensen: https://www.youtube.com/watch?v=umPAonV20cM
The IMO website: https://www.imo.org/
Michael’s Substack on the IMO decision: https://mliebreich.substack.com/p/imo-members-choose-between-the-us