AMOC, Plankton, and the High Seas Treaty: Ocean Science and Governance at Hay Festival

Overview

In this BBC Inside Science episode from the Hay Festival, hosts and guests explore the ocean as a climate engine, the crucial but underappreciated role of plankton in biodiversity and the carbon cycle, and the implications of the new UN High Seas Treaty for marine protection and resource sharing.

• The Atlantic Meridional Overturning Circulation AMOC and its weather impacts are explained in accessible terms.
• Plankton is highlighted as a foundational driver of life on Earth, not merely a food source for larger marine animals.
• Discussion of the High Seas Treaty focuses on marine protected areas, governance, and fair distribution of ocean benefits.
• The conversation touches on geoengineering and the need for careful science-led policy making.

Introduction and the Hay Festival moment

The podcast opens by setting the Hay Festival as a stage for discussing the momentous topic of sea politics and science. The guests, Vincent Dumezel and Helen Chersky, bring distinct perspectives — economics and environmental science — to how we think about the ocean as a global commons and as a driver of climate and life on Earth.

Ocean Currents and the Liquid Engine

The discussion centers on currents as a planetary conveyor belt. The hosts describe the ocean as a kinetic engine that moves heat, nutrients and carbon around the globe. A key focus is the Atlantic Meridional Overturning Circulation AMOC, a deep and slow component of ocean circulation that transports heat north and returns cold water south at depth. The guests clarify that AMOC is not simply the Gulf Stream surface current; the important process is the downward sinking and deep return flow that constitutes overturning and heat transport. The speakers explain that direct measurements of AMOC are limited to a few decades, making future predictions challenging and uncertain, but the potential for a significant slowdown remains a motivation for action rather than a reason for fatalism.

Plankton as a Central Engine

The Plankton Manifesto is introduced as a call to recognize plankton as a central player in global biogeochemical cycles. Plankton ecosystems extend far beyond visible organisms and include tiny bacteria, archaea, diatoms and other microalgae that drive photosynthesis, carbon sequestration, oxygen production and nutrient cycling. The guests emphasize that plankton have shaped Earth’s climate for billions of years and that modern science now has tools to map and understand their diversity and functions at scale through genomics, satellites and sensors. The conversation frames plankton as a source of hope and innovation rather than doom, noting the vast, still largely untapped genetic reservoir in the oceans.

High Seas Treaty and Marine Governance

The host asks about the High Seas Treaty, and Vincent responds with an assessment of its significance after two decades of negotiation. The treaty is described as a framework to establish marine protected areas and to redefine how benefits from ocean resources are shared, including questions about biobanking, access to marine genetic resources, and equitable distribution of profits. The discussion highlights copa — the key ocean plankton area — as a concept within the treaty that could help ensure plankton-rich regions receive protection and sustainable management. The guests also discuss the governance gaps that remain, such as the governance of 65 percent of the ocean that is outside national jurisdiction, and the need for standardized protection measures to enable 30 by 30 protected area targets.

Policy, Ethics, and the Path Forward

The conversation turns to policy implications and the social dimensions of ocean science. The speakers stress that action is needed now, with attention to the uncertainties around AMOC and the ecological and economic importance of plankton. They consider the potential for biotechnological innovations drawn from marine genes and the importance of avoiding neocolonial patterns in access to marine resources. The segment ends on a hopeful note, underscoring the role of sober, science-based policy making and international collaboration in turning knowledge into stewardship of the oceans.