About Geological Net Zero (GNZ)

Origins and Development of an Initiative for Fossil Carbon Responsibility

Geological Net Zero (GNZ) is an initiative aimed at promoting responsible management of fossil carbon, from its extraction to its permanent sequestration.

It builds on international scientific research, proposals for fossil fuel producer responsibility, and collaborative work among geoscientists, energy professionals, and climate policy specialists.

GNZ seeks to connect scientific understanding, industrial transformation, and international cooperation to address the growing imbalance caused by the transfer of fossil carbon from geological reservoirs into the atmosphere, oceans, and biosphere.

Scientific Foundations

The work of Myles Allen and his colleagues, particularly at the University of Oxford, has made important contributions to understanding the relationship between cumulative CO₂ emissions and global warming, as well as the need for permanent geological sequestration of fossil carbon.

As early as 2009, they proposed linking continued fossil fuel use to mandatory carbon sequestration.

Margriet Kuijper and her colleagues contributed to developing the Carbon Takeback Obligation (CTBO), an approach based on extending producer responsibility to the permanent storage of CO₂ associated with fossil fuels.

These scientific and policy contributions provide important foundations for Geological Net Zero, while representing distinct research initiatives and institutional approaches.

Early GNZ Proposals (2019–2022)

Beginning in 2019, Patrick Portolano, through EOSYS and discussions within ACP Énergies, explored ways to strengthen fossil carbon producer responsibility and support the transformation of energy industries.

Laurent Nicolas contributed to this work, particularly through the concept of a Fossil Carbon Indicator and proposals for the transition toward more responsible and circular fossil carbon industries.

Together, Laurent Nicolas and Patrick Portolano authored:

Towards Responsible Circular Fossil Carbon Industries: Upstream Proposals to Reduce Demand and Control Supply

Working paper, May 2021; revised September 1, 2021 — 25 pages.

This work explored complementary upstream approaches to reducing fossil carbon demand, controlling supply, and establishing greater accountability throughout fossil carbon value chains.

In October 2021, Patrick Portolano published a foundational paper for COP26 proposing an international agreement on Geological Net Zero. The paper was developed through discussions with British geoscientist Hugh Richards, who contributed to shaping the approach and to the adoption of the term Geological Net Zero in their work.

These exchanges subsequently led to the joint paper:

“Geological Net Zero” (Geological Carbon Neutrality) — How Could We Get There?

Hugh Richards and Patrick Portolano — January 2022; revised March 25, 2022.

This second paper further explored the political and institutional pathways for implementing GNZ. It examined the strengths and limitations of the Carbon Takeback Obligation, the prospects for an international treaty or pact, and the potential role of major fossil carbon-producing countries.

The paper also benefited from constructive comments by Margriet Kuijper and observations from Paul Zakkour, which informed revisions and clarifications in the March 2022 version.

ACP Énergies: Collaborative Work from 2019 to 2024

Between 2019 and 2024, a working group within ACP Énergies contributed to the development and dissemination of proposals addressing fossil carbon responsibility and the transformation of energy industries.

Bringing together professionals from the energy, geoscience, and industrial sectors, including Patrick Portolano and EOSYS, this work addressed several interconnected issues:

  • Producer responsibility and its extension throughout fossil carbon supply chains.
  • Fossil carbon accounting and traceability.
  • Transformation of fossil carbon industries and energy systems.
  • Defossilization and the development of sustainable alternatives.
  • Geological carbon sequestration and its financing.

These discussions contributed to several publications and proposals associated with COP26, COP27, and COP28, as well as contributions to French energy and climate policy debates.

They provided an important collective framework for the development of the GNZ initiative.

EOSYS and the Continued Development of GNZ

Founded in 1993, EOSYS is a French geosciences company specializing in subsurface studies, geological and geophysical modeling, and projects involving natural resources and energy.

Under the leadership of Patrick Portolano, EOSYS continues to develop and promote Geological Net Zero, drawing on its experience in geosciences, subsurface engineering, and carbon storage.

The initiative seeks to bring together researchers, industrial stakeholders, policymakers, and institutions around practical pathways toward geological carbon neutrality.

GNZ is organized around two complementary proposals:

The GNZ Principle establishes the objective of geological carbon neutrality and the associated responsibility for fossil carbon.

The GNZ Pact proposes a framework for cooperation among the stakeholders involved in the carbon cycle, supporting the collective implementation of that objective.

Both are presented in detail on dedicated pages.

An Open Initiative Building on Existing Contributions

Geological Net Zero is part of a wider international effort to address fossil carbon emissions, producer responsibility, the phase-down of fossil fuel dependence, and permanent carbon sequestration.

It recognizes the scientific and policy contributions of researchers and organizations working on these challenges while developing a complementary approach based on shared responsibility and cooperation across fossil carbon value chains.

GNZ is an open initiative, intended to encourage cooperation among scientific, industrial, financial, and institutional stakeholders.

Its broader ambition is to help prevent further disruption of the geological carbon balance while supporting the long-term removal of excess carbon already accumulated in the climate system.

Foundational Publications and Further Reading

Scientific foundations

GNZ and ACP Énergies publications

Explore the Foundational Papers

Discover the GNZ Principle · Explore the GNZ Pact

Geological Net Zero — Shared responsibility for restoring the geological carbon balance.